Historic Ground Failures in Northern California …HISTORIC GROUND FAILURES IN NORTHERN CALIFORNIA TRIGGERED BY EARTHQUAKES By T. L. you^ and S. N. Hoos~ ABSTRACT A major source of

Youd, T. L., and Hoose, S. N. (1978). "Historic ground failures in northern California triggered by earthquakes." U.S. Geological Survey professional paper 993, U.S. Govt. Print. Off., Washington, iv, 177 p.

Historic Ground Failures in Northern California Triggered by Earthquakes

By T. L. YOUD and S. N. HOOSE

G E O L O G I C A L S U R V E Y P R O F E S S I O N A L P A P E R 9 9 3

U N I T E D STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1978

Charles Scawthorn

Text Box

Youd, T. L., and Hoose, S. N. (1978). "Historic ground failures in northern California triggered by earthquakes." U.S. Geological Survey professional paper 993, U.S. Govt. Print. Off., Washington, iv, 177 p.

UNITED STATES DEPARTMENT OF THE INTERIOR

CECIL D. ANDRUS, Secretary

GEOLOGICAL SURVEY I

W.A. Radlinski, Acting Director

Library of Congress Cataloging in Publication Data Youd, T. Leslie Historic ground failures in northern California triggered by earthquakes. (Geological Survey Professional Paper 993) 1 Bibliography: p. 68-71. 1. Earth movements-California. 2. Earthquakes-California. I. Hoose, S. N., joint author. 11. Title. 111. Series: United States. Geological, Survey. Professional Paper 993. QE598.2.Y68 624'.176 77-608366

FOI sale hy the Superintendent of ~ o c u m e " t s , U.S. Goiernment Printing Office

Washington, D.C. 20402 Stock Number 024-001-03060-8

CONTENTS

Page Abstract .................................................. 1 Introduction .............................................. 1 Area of investigation ...................................... 2 Rainfall and ground water conditions in 1906 .............. 2 Ground failure types ...................................... 4 Limitations of ground failure data .......................... 5

................ Distribution and character of ground failures 9 Monterey Bay counties region .......................... 13 San Francisco Bay counties region ...................... 23

Santa Cruz Mountains ............................ 23

Page Distribution and character of ground fai1ures.X ontinued

San Francisco counties region-Continued San Francisco Bay. Santa Clara Valley and east bay

hills area ...................................... 23 San Francisco City and County .................... 24

North bay counties region .............................. 60 North coast counties region ............................ 66

Summary and conclusions .................................. 67 References cited .......................................... 68

ILLUSTRATIONS

[Plates are in pocket1

PLATE 1 . Location map of ground failures in the Monterey Bay counties region . 2 . Location map of ground failures in the San Francisco Bay counties region 3 . Location map and of ground failures in San Francisco City and County . 4 . Location map of ground failures in the north bay counties region . 5 . Location map of ground failures in the north coast counties region .

FIGURE 1 . Map of northern California showing areas in which earthquake-triggered ground failures have occurred .......... 2 . Graphs of monthly rainfall data for the 190&06 water year compared with average rainfall data ................ 3 . Map showing rainfall distribution in California during March 1906 ............................................ 4 . Graphs of daily rainfall data for March and April 1906 ........................................................ 5 . Map showing 1906 earthquake intensities for San Francisco County ............................................ 6 . Map showing 1906 earthquake intensities for Western United States ..........................................

7.10 . Photographs showing: 7 . Damage a t Spreckels sugar mill as a consequence of lateral spreading during 1906 earthquake .............. 8 . Barley field near Spreekels disrupted by slumping and lateral-spreading failures ............................

.............. 9 . County road along Salinas River, south of Salinas, disrupted by slumping and lateral spreading 10 . South terminal pier of bridge over Salinas River . Surficial deposits shifted about 6 ft (2 m) toward the river ..

11 . Geotechnical section across the Salinas River ................................................................ 17-29 . Photographs showing:

12 . Damage a t Moss Landing caused by lateral spreading .................................................... .......................... . 13 Ground failure scarp near the south bank of Pajaro River across from Watsonville

.................................... . 14 Graben and damaged buildings caused by lateral spread in Watsanville .............................................................. 15 . Slump scarp and sandboil near Pajara River

16 . Sandboil near Wat~onville .............................................................................. ............................ . 17 Ruptured abutment of county road bridge over the Pajaro River near Chittenden

18 . Hillside landslide in a redwood forest near Alma .......................................................... ............................ . 19 Deer Creek landslide that destroyed the Hoffman Shingle Mill and took one life

20 . Flow failure in hills southeast of Half Moon Bay .......................................................... 21 . Flow failure east of Half Moon Bay ...................................................................... 22 . Flow failure 4 mi (6.4 km) east of Half Moon Bay ........................................................

...................... . 23 Rockfalls along coastal bluffs between Ocean Avenue, San Francisco, and Mussel Rock 24 . Landslide an ~ t e e p hillside near Mussel Rock ............................................................ 25 . Cavity of flow failure above Mt . Olivet Cemetery near Colma ..............................................

...................... . 26 Rails of electric railway on marsh west of San Bruno that were buckled by compression 27 . Ground cracks in the "icinity of Coyote Creek west of Milpitas ............................................ 28 . Sand boils in field between Milpitas and Coyote Creek ....................................................

29 . Geotechnical section across Coyote Creek a t the Alviso-Milpitas road bridge ....................................

In

IV CONTENTS

FIGURE 30 . Aerial photograph of commercial and shipping district of San Francisco showing ground failure zones ............ ................ 31 . Photograph showing cracks and separations in roadway pavement near San Francisco water front

32 . Geotechnical section beneath Market Street .................................................................. 33 . Photograph showing dlstruprion of block pavement and sidewalk on Columbln Street just sourh of Folsom Street . . . 34 . Photograph shuw~ng pulled-apart rails on Flfth Strert near Harrlson Street ................................

~ . ~ .

35 . Photograph showing damage to San Francisco Post Office caused by ground failure .............................. ........ 36 . Geotecbnical profile across south of Market zone a t James Lick Skyway between Third and Sixth Streets

37 . Schematic diagram of area between Ninth andTenthStreets andBryant and Brnnnan Streets in lower part of Mission Creek zone, San Francisco, showing locations and directions fmm which photographs in figures 3 U 1 were taken ..

38-41. Photographs showing: 38 . View along Dore Street from Bryant Street toward Brannan Street ........................................ 39 . Scarps and right-lateral displacements caused by lateral spreading a t two points on Bryant Street near the

intersection of Ninth Street .......................................................................... 40 . Views along Ninth Street between Bryant and Brannan Streets ............................................ 41 . View northeastward an Brannan Street, corner of Ninth Street .............................................

42 . Schematic diagram of area between 17th and 18th Streets and Capp Street and South Van Ness Avenue in the central part of Mission Creek zone, San Francisco, showing locations and directions from which photographs in figures 43-47 were taken ......................................................................................

43-50 . Photographs showing: 43 . Buckling of rails by compression an Howard Street (South Van Ness Avenue) near 17th Street .............. 44 . South Van Ness Avenue in San Francisco with rails offset by lateral-spreading ground failure .............. 45 . Scarps showing vertical movement and northward lateral movement on 18th Street ........................ 46 . Scarps with lateral and vertical displacements in Capp Street between 17th and 18th Streets ................ 47 . Buckled curbstone on Capp Street near 18th Street ........................................................ 48 . Valencia Street between 17th and 18th Streets ............................................................ 49 . Photograph of San Francisco in fiames after 1906 shack .................................................... 50 . Lateral-spread at the Youth's Directory on 17th and Guerrero Streets ......................................

51 . Geotechnical section across Mission Creek zone .............................................................. 5 2 6 7 . Photographs showing:

52 . Distruption of Van Ness Avenue over a filled-in ravine .................................................... 53 . Slump in Union Street between Pierce and Steiner Streets ................................................ 54 . Flow failure along shoreline of Lake Merced triggered by the 1957 Daly City earthquake .................... 55 . Cracks a t Bolinas Lagoon ................................................................................ 56 . Cracks along the edge of a sag pond near Bolinas ........................................................ 57 . Tipping of buildings into the water a t the Balinas waterfront .............................................. 58 . Cracks and settlement a t the head of a lateral spread between Olema and Inverness ........................ 59 . Cracks generated by lateral spread southwest of Point Reyes Station ...................................... 60 . Cracking and subsidence of road grade across a marsh southwest of Point Reyes Station .................... 61 . Ridged bottom of Tamales Bay after 1906 earthquake ...................................................... 62 . Shifted sediments of Tomales Bay ........................................................................ 63 . Boat piers a t Invernessdisplaced duringearthquake ...................................................... 64 . Hillside Row failure near Inverness ...................................................................... 65 . Hillside landslide in roadcut west of Inverness ............................................................ 66 . Landslide on east side of Garcia River Valley ............................................................ 67 . Cape Fortunas (False Cape) landslide, one of the largest landslides triggered by the 1906 shock ..............

TABLES

Page

TABLE 1 . Northern California earthquakes of 1769-1970 associated with reported ground failures ........................ 3 2 . Excerpted notes containing general descriptions of the types, character, and locations of ground failures associated

with the 1906 San Francisco earthquake .................................................................. 6 .......... 3 . Excerpted notes containing general descriptions of ground failures in the Monterey Bay counties region 14

.... 4 . Excerpted notes containing general descriptions of ground failure and consequent pipeline breaks in San Francisco 26 5 . Specific deseri~tions of mound failures in the Monterev Bay counties r e ~ o n ........................................ 74 . . 6 . Specific descriptions of gmund fadurcs in the S m Francisco Bay counties refion ................................... 88 7 . Specific dcscnptions of ~ w u n d failures in San Francisco City and County ......................................... 125 8 . Specific descriptions of ground failures in the north bay counties region ............................................ 147

...... 9 . Specific descriptions of gmund failures in the north coast counties region ................................... 1 164

HISTORIC GROUND FAILURES IN NORTHERN CALIFORNIA

TRIGGERED BY EARTHQUAKES

By T. L. you^ and S. N. H o o s ~

ABSTRACT

A major source of earthquake-related damage and casualties in northern California has been ground failures generated by the seismic shaking, including la~dslid~J,,la~ef.a~~~f~~d~!, .gr~unr.~sLIs: ment, andsurface cracks. The historical record shows that, except far ashore shocks, the area affected and the qu~antity and

/ general severity of ground failures increase markedly with Richter magnitude. Hence, the largest historical event, the 1906 San Fran- cisco earthquake, has been the most important generator of ground failures. Because of recent population growth and land development in northern California, the potential for damage in future events is enormous compared with that existing in 1906.

Reports of the 1906 San Francisco earthquake and other northern California earthquakes and descriptions of ground failures therein are used to (1) identifv and clarifv the tvoes of mound failures as- -. - sociated with earthquakes, (2) provide a guide for engineers, plan- ners, and others responsible for minimizing seismic hazards, and (3) form a data base for other geotechnical studies of earthquake- triggered pound failures.

ential settlements, and ground cracks. In this study, earthquake reconnaissance reports and newspaper reports from past events in northern California are re- viewed, and ground failures described therein are identified, classified by present criteria, and located on modern maps.

The purposes of this study are (1) to identify and clarify the types of ground failures associated with earthquakes, (2) to provide a guide for engineers, plan- ners, and others responsible for minimizing seismic hazards, and (3) to form a data base for further geotechnical studies of earthquake-triggered ground failures. ~ ~

Each reported ground failure site has been given a location number, and descriptions of that failure excerpted from the literature are tabulated by location

influence on ground failure development as well as distance from the causative fault. Areas especially vulnerable to ground failure in northern California have been oversteepened slopes, such as mountain cliffs, streambanks, and coastal bluffs, and lowland deposits, principally Holocene fluvial deposits, deltaic deposits, and poorly compacted fills. Liquefaction has been the direct cause of most lowland failures. The historical record suggests that ground failures during future large earthquakes are most likely to occur a t the same or geologically similar locations as failgres during previous earth- m,rka.

~;alogie, hydrologic, and topographfc setting have an important

y--.."".

INTRODUCTION

/ ndmber in tables 5-9. The location number is entered

Earthquakes are one of the most perilous natural hazards affecting northern California. One great (Richter magnitude, M, greater than 8) and several major (M greater than 6) earthquakes have struck that region in historic time (last 200 years). These shocks caused extensive property damage and inflicted several hundred casualties. Because of large population growth and land development in recent years, the potential for damage in northern California is enormous today compared with that existing in 1906, the date of the last major destructive shock.

A principal cause of past earthquake damage and casualties has been seismically generated ground failures in the form of landslides, lateral spreads, differ-

on the appropriate plate near the location of the failure, and a symbol indicating the inferred type of failure is placed as accurately as possible on the plate over the corresponding failure site. This classification symbol is also entered in the descriptions of failures at that location number along with a letter symbol indicating the geographical accuracy with which the failure can be relocated on modern maps. Ex~lanations for the classification symbols are given on each plate and in the notes to the descriptions of failures; also, explanations for the accuracy symbols are listed in these notes.

Acknowledgments.-We gratefully acknowledge the psistance of the following individuals and organiza- tions who contributed to this study by providing information, photographs, and helpful suggestions: Grace Curtis, Pajaro Valley Historical Society; Clyde Ar- buckle, former San Jose City historian; Jarvis McGo- wan, resident of Monterey County; Albert T. Vierra, Sr., resident of Moss Landing; Hans Struve, resident of Moss Landing; John Hughes, resident of Salinas; Salinas Valley Historical Society; Henry J. Degenkolb and Associates, San Francisco; The Bancroft Library, University of California, Berkeley; Stanford Univer- sity Archives; San Francisco Public Library; Humboldt

2 HISTORIC GROUND FAILURES IN NORTHERN CALIFORNIA TRIGGERED BY EARTHQUAKES

State University Library; Mary Lou Malhern, Bay Area Rapid Transit District; George Litros, Berkey Photos (formerly Bear Photo); Charles A. Smallwood, resident of San Francisco; M. G. Bonilla, Albert T. F. Chen, Jackie Freeberg, Edwin L. Harp, and Julius Schlocker, U.S. Geological Survey.

AREA OF INVESTIGATION

The region considered in this study (fig. 1) extends from the southern parts of Monterey, Kings, and Tu- lare Counties (approx lat 36' N.) on the south to the Oregon border (lat 42" N.) on the north and from the Pacific Ocean on the west to the Nevada border or crest of the Sierra Nevada Mountain range on the east. The

FIGURE 1.-Map of California showing Coast Ranges province, areas covered by regional maps, and areas in which ground failures have occurred during historic northem California earthquakes.

area affected by the 1872 Owens Valley, Calif., earthquake was thus excluded from consideration in this report.

Although earthquake vibrations have been felt historically over all of northern California, ground failures of greater than very slight severity (table 1) have been reported only from a narrow strip along the Pacific Coast that lies almost entirely within the Coast Ranges province (fig. 1) (Bailey, 1966, p. 2). This does not mean that severe earthquake-induced ground failures cannot occur in other areas, but rather that they have not in recent times.

Geographically the Coast Ranges province forms a band along the coastline of northern California that extends inland as far as 70 miles (110 km) from the Pacific Coast. The province is composed of several northwest-trending mountain ranges and intermontane valleys. The ranges are made up of Mesozoic and Cenozoic rocks that have been faulted and folded (Christensen, in Bailey, 1966, p. 305313). The larger valleys commonly are deeply alluviated and traversed by meandering rivers and streams. The most important structural feature in the province is the San An- dreas fault, which strikes approximately N. 35" W. and cuts across the general trend of the mountain ranges at a small angle (Oakeshott, in Bailey, 1966, p. 357-3721, Most northern California earthquakes are associated with movements on this fault or subsidiary faults in the San Andreas fault system.

Historic earthquakes in northern California that have triggered ground failures are listed in table 1, and approximate epicentral locations are plotted on figure 1; for the 1906 San Francisco and 1868 Hayward earthquakes, the approximate zones in which ground failures occurred are delineated. This figure confirms that the 1906 San Francisco earthquake is by far the most significant event for ground failure studies in this region because of the vast area affected and also the,, number and severity of the failures generated. The1 i tabulation also shows that earthquakes with mag-! : nitudes less than 4 have produced no reported (and1 i thus no consequential) ground failures. Above mag- 1 nitude 4, severity of generated ground failures gener- ; ally increases with magnitude.

RAINFALL AND GROUND WATER CONDITIONS IN 1906

Ground water conditions are an important factor controlling development of many seismically generated ground failures, especially those associated with liquefaction. In most upland areas, ground water conditions at any given time are dependent on antecedent climatological conditions, particularly precipitation.

RAINFALL AND GROUND-WATER CONDITIONS IN 1906 3

TABLE 1.--Northern California earthquakes of 1769-1970 associated with reported ground failures ISeverity of ground failure is dnssified as fallowa: Very s l ight ia few minor ground cracks or landslides in a small localized srea: Slight-several instances of minor ground crack and

lnndslides over an area of several square milcs; Moderstdamaging or potentially damaging ground cracks and landslides aver an area of several tens of square miles; Severe-. large gmund cracks and landslides over an area ofacvcral hundreds of square miles or more. Laeation numbers are assigned to ground failure sites in areas covered by plates 1-5. Dcseriptions of failurea nre given by location number in tables 69. Data fmm Corman and van Hake (1973); Holden (1898); Townley and Allen (1939); Wood. Allen, and ~ e e k (193911

Year Date Epicentrsl area Maximum Modified Richter Severity of Location Mercali intensity magnitude K: No.

1800 Oct. ll(?) 1836 June 10 1838 June 1852 Nov. 2%24 1853 Oct. 23 1855 Jan. 24 1857 Jan. 9 1861 July 3 1865 Oct. 1 1865 Oct. 8

1866 Feb. 17 1868 Oct. 21

San Juan Bautista .................................... San Francisco Bay ........................ IX-X

Maderate(?) .......... .......... Moderate(?)

Moderate to severe(?). .......... Moderate(?)

Very slight .....7....

.... do -...............

.... do ................

San Frnnclsco Bay area ............... X San Francisco peninsula ............... VIll Eureka ............................ VlIl

.......................................... Downieville Fort Tejon ................................ IX Contra Costa-Alameda Counties .......... VIII Fort Humholdt and Eureka ................ VIII-IX Santa Cruz Mountains .................... VIII-IX

.... do ................

.... do -----........... ............ Moderate

Klamath River ........................................ Hayward ................................ IX-X

Moderate(?) .......... ............ Moderate

1883 Oet. 22 1885 Mar. 30 1890 Apr. 24 1892 Apr. 19 1892 Apr. 21 1898 Mar. 30 1898 Apr. 14 1906 Apr. 18 1908 Aug. 18 1915 Feb. 21 1915 Apr. 5 1919 Jan. 4 1923 Jan. 22 1926 July 25 1927 Aug. 20 1932 June 6 1933 May 16 1947 June 22 1953 Dec. 16 1954 Apr. 25 1954 Aug. 12 1954 Sep. 15 1954 Dec. 21 195'7 Mar. 22

Merced River ............................ Southeast of Hollister .................... Monterey Bay region ......................

................................ Vacaville .................................. Winters

Mare Island .............................. East of Mendocino ........................

............................ San Francisco .................................. Eureka

Near Lassen Peak ........................ .......................... Coleville region

............................ Shasta County Upper Mattole & Petrolia .................. Near Idria, San Benito Co ................

............................ Humboldt Bay Humholdt County ........................ Fremont ..................................

............ VII VII IX IX

VIII VIII-IX

XI VII

.......... Very slight .... do ---............. Slight ................ .... do ................ .... do ................

.......... Very slight .... do ................ Severe ..............

.......... Very slight Slight(?) .............. Very slight .......... --.. do -----........... .... do --..............

f&t locations 348.

......... IX VII VIII VIII VII VI VI

VIII VI VI VII VII

do 6 ........---. -------......... ........ Slight to moderate .... 353

................ 6.4 Slight 345 . . Vew slight .......... 165

Gilroy .................................... Watsonville .............................. East of Watsonville ...................... .--.do .................................... East of Merced ............................ Eureka-Arcata .......................... West of Daly City ........................

.... do ................ ............ Moderate

.... do ................

Very slight .......... Slight ................

.......... Very slight .... do ................ -...do ---............. ..-.do ................ .... do ................ --..do ---............. -... do ---............. .... do ................

.............. 340,34%354 132, 133,232, 235242 132 31,47 334 near 310 29,30 180 48 338 295

1958 Dec. 11 1959 Mar. 2 1961 Apr. 5 1962 June 6 1963 Sep. 14 1965 Sep. 10 1967 Sep. 28 1968 June 25 1969 Oct. l 1970 May 18

Southwest of San Francisco ................ Near Gilroy .............................. Humboldt County .......... I ............. Near L a k e ~ o r t ............................ ...........

VII VI VI VII

VII-VIII v

East of Watsonville ...................... Pittsburg ................................

.............................. Morgan Hill Petrolia-Honevdew ......................

.............................. Santa Rosa Fort Jones area ..........................

Precipitation varies considerably in the Coast Range province, both in time and in location. Average rainfall is in excess of 100 in. (2,500 mm) per year in some areas near the Oregon border but generally decreases southward to as little as 12 in. (300 mm) per year at some points in the southern Coast Ranges. Locally the average rainfall is variable, generally being greater nearer the ocean and at higher elevations. Rainfall over the entire area is seasonal, with the bulk of the

major storms occurring in the months of October to May (Sprague, 1941, p. 795796).

Of special interest to this study are the rainfall records for the winter immediately preceding the 1906 San Francisco earthquake, (McAdie, 1906; U.S. Weather Bureau, 1912.) The 190506 monthly rainfall i records for five stations in the coastal section of north- j : ern California (fig. 2) indicate that precipitation during '; j the 190506 year was from 7 to 76 percent greater than !


19064 21.15 in.

19054 59.7710.

O S M 0 5 M 0 5 M 0 5 M 0 5 M O E M 0 6 M 0 5 M 0 6 M 0 6 M 0 6 M 06M

J U I ~ A " ~ . sPpt. act. N ~ " . D ~ = . la". mb. M ~ , . A~. I I M~~ J~~~

EXPLANATION

0 El T ~ o n t h i y rainfail for month nveiage monthly rain far^ ~ r a e s of rdnfatl. not

indicated during 19054 maarurab~s

FIGURE 2.-Monthly rainfall data from several northern California stations for the 1905-06 water year (U.S. Weather Bureau, 1912), compared with average monthly rainfall data (Environmental Data Service, 1971) for those same stations.

normal at the selected stations and that March was an exceptionally wet month with rainfall ranging from 50 to 200 percent above normal. A statewide rainfall map

March 1906 is plotted on figure 3. March and April, 1906, daily rainfall records from

three coastal stations are plotted on figure 4. These data show that the last major storm prior to the 1906 earthquake occurred during the last few days of March and that no significant precipitation fell in the 17-day

Monthly precipitation MARCH 1905

SCALE OF SH,AOES,

0 0 TO 2.00 in.

2.00 to 4.00 in.

400 10 6.00 in.

6.00 to 8.00 in.

FIGURE 3.-Map showing rainfall distribution in California during March 1906 (after McAdie, 1906, p. 35).

period immediately preceding the earthquake. This information suggests that the ground water level was probably high at the time of the earthquake and that

\-

the soils above the water table probably were fairly ' : well drained. These soil moisture conditions contributed to the development of ground failures during the 1906 earthquake.

GROUND FAILURE TYPES

Ground failure is defined as a permanent ground movement (Youd, 1975). In this report only those ground failures triggered by seismic shaking are sidered, including various types of landslides,

of these failures are commonly caused by liquefaction, spreads, ground settlement, and ground

which is defined as "the transformation of a granular \,\ material from a solid state into a liquefied state as a 1 ?/

conse~uence of increased pore-water pressures" (Youd, 1973, 1975). Ground failures are categorized herein as ' '

follows: Hillside landslides include rotational slumps, block glides, soilfalls and rockfalls, shallow debris ,i landslides, and flows (Varnes, 1958,1978; Youd, 1975); valley floor-failures include lateral spreads, slumping of streambanks, and ground settlement (Varnes, 1958, 1978; Youd, 1975); miscellaneous ground cracks in-

! (cracks caused by direct tectonic movements were not j generally considered) that were, apparently, not gen- ! erated by another form of ground failure. Other , ,

i 'phenomena considered because of their relation to i 'ground failure include sand boils arid disturbances of I artesian wells. All the classifications given on the

plates and in the descriptions of failures (tables 5 9 ) are those inferredby the authors from written descriptions and modern geological and geotechnical reports and maps.

Hillside ground failures generally are easily recognizable in the literature from the terminology or descriptions given. Most authors referred to hillside landslides as "landslides" with no further details given. In

:the State Earthquake Investigation Commission report (Lawson, 1908) the subclasses slumps, rock avalanches, and earthflows are used. Some general de- scriptib;iis-af the character and distribution of hillside landslides triggered by the 1906 San Francisco earthquake are contained in notes 1-8 of table 2.

Descriptions of valley floor ground failures vary greatly in their clarity and detail. sj.umped .stream; banksgenerally , are easily recognizable from published

LIMITATIONS OF

sari ~ ~ ~ ~ i ~ ~ ~ . ~di i .

,,,,,,,,a,,,,, n o m a b e

~~~~h A ~ . ~ I

, FIGURE 4.-Daily rainfall data at three coastal stations for March slid April 1906 (data from McAdie, 1906, p. 32-45),

/ cluae all surficial fissures triggered by seismic shaking

Although there are many notations of ground failure in the historical record for northern California, the data still are limited and incomplete for the five following reasons: (1) Most postearthquake investigative efforts were applied to assessing the extent of structural and other damage or tracing out ruptured faults; hence notations concerning ground failures are commonly of incidental nature, and many ground failures not critical to constructed works may have been neglected. (2) The incidences of ground failures, particularly landslides, were so numerous in some localities during the 1906 shock that careful noting of each occurrence was practically impossible (see note 1, table 2). (3) The areal coverage of postearthquake investigations has been uneven, and some omissions exist. Areas in and near centers of population, along major transportation routes, and along major faults have generally received much more attention than less developed, less relevant, or more remote areas. (4) Several major earthquakes occurred before modern investigative proce- dures were developed or before it became routine to

GROUND FAILURE DATA 5

descriptions; however, in some instances classifications were inferred from descriptive evidence such as cracks and vertical separations along stream channels. Evi- dence used to categorize ground movements as lateral spreads include notations of lurching (most phenomena generally termed as lurching are, in fact, lateral spreads associated with liquefaction (Youd, 1973, 1975j); ~~n t rac t ion of stream channels; lateral, extensional or compressional displacements of fences, sfreets, pipelines, rails, and other constructed works; and laterally shifted intertidal marsh deposits. Pub- lished notes describing the typical character and extent of lateral spreads during the 1906 event are given in notes %18 of table 2.

Ground movements were classified as settlement on thebasis of vertical displacements not apparently associated with landslide movements. Evidence of ground.settlement includes relative downward movement of the ground surface around well casings and structural pilings and relative vertical displacement of the earth's surface beneath structures such a s roadways and buildings. General notes concerning settlement during the 1906 earthquake are included in notes $18 of table 2.

The category of miscellaneous ground cracks includes cracks and fissures that on the basis of published descriptions cannot be related to tectonic faulting, landslides or ground settlement. General descriptions of the character and distribution of many such cracks generated during the 1906 event, both on hillside and in valley floor deposits, are given in notes I S 2 4 of table 2.


TABLE ?..-Excerpted notes containing general descriptions of the types, character, and locations of ground failures associated with the 1906 Sun Francisco earthquake

Note Relerence Quotation

Hillside landslides

1 Lawson and others, 1908, p. 390.

2 Lawsonand others, 1908, p. 385.



5 Anderson, 1907, p. 643.



8 Gilbert, Humphrey, Sewell, and Soul6, 1907, p. 133.

By far the most common manifestation of landslide phenomena was that here referred to as earth-slump. It would be wearisome to attempt to mention all the various earth-slumps stimulated by ttiee-eartliquake, even if information were sufficient1 detailed to make this ossible.

Thruout the Coast Ranges of zalifornia the small resiiual stability of many earth-slumps was overcome by the I vibration of the ground a t the time of the earthquake of April 18 and they were caused to slump forward. In

many other instances new earth-slumps were started, owing to the same general cause. Earth-flows originated in valleys, in gullies, or on hillsides. Where the weight of the earth, combined with the

weight of the add$ water, was sufficient and the substratum of the soil was rendered plastic, gravity caused it to creep like a lava-stream, leaving a hollow in the place from which it came and a fan or tongue of debris down the slope below. Movement was especially apt to ensue where the ground had been previously wet, the intensity of the earthquake shock being particularly great a t such points and the tendency ofthe vibrations being to set the mass in motion. Earth-flows occurred in many places in the Coast Ranges, and probably throughout the region in which the shock was heavily felt. The writer found many of them, large and small, on the San Francisco Peninsula and in the Santa C m Mountains, also in the Mount Diablo and Mount Hamilton Ranges.

Similar [flow] landslides, tho usually of smaller size, occurred throughout the region neighboring the fault vlslted by the writer, and even in districts at a considerable distance from the fault. Frequently they werenot definitely referable to the earth-flow type, but resembled more closely earth-dumps formed without the aid of a suddenly increased water supply. It was often difficult, especially in cases where the movement was slight, or the slide was in the embryonic stage, to determine whether the earthquake a t those points had caused a flow ofwater or not. *** Many slips were formed on hillsides and along the embankments of mountain roads, and along the cracks formed by the shock in moist and lwsened soil. O&en these slips were arranged one above another, the perpendicular faces due to slipping having the appearance of step faults. In such cases the weight of the moved mass and the amount of water was not sufEcient to cause the material to flow. *** In some places bare ridges . had their lines oCjynlmctry broken into .ittle knolls and irrcgularrties by these dips, a common occurrence rn the hills of.i~R sand formntluns in the nonhcrn pan ofthe Snn Francjsco Peninsula. All the sl~psjust referred to illustrated the rradntinn benvren eanh-s1umo.i and eanh-flowr;. Doubtlesi in man" of them a small amount -~ ~

-~ ~~~~~~ r- ~~~~ ~~ ~ . - - ~~ ~ ~~~ ~ ~

e of water did eather as a result of the earthauake. Earth-flows weFe of frequent occurrence in tke Coast ranges, the writer finding them numerous on the San

Francisco peninsula and in the Santa C r u mountains with," a scoreafrn~lcsol'ihe fault, and what appeared tu be flows ofs:milar arigtn at a much grcatsr drstance from the epicentrum. They were formed on gmtle as well as s t e e ~ ~ l u ~ e s , nnd hoth in orev>ouslv drv druln:lee dc~ressluns and on convex hillsides in the laruest llowd thousands iftoins of earth and rock detritus were re&v& and carried hundreds of yards, leaving g r e a cavities. In one case a hole ten feet deep was excavated over an area of nearly an acre o n a five-degree ilope, and the materinl removed was spread over two acres

-"'There is still another [type of landihdr], which is ~mmediatcly sssociated wlth eanhquekcs as n cause of movement. 'This 1s the shdc of drv eanh and ruck upon ~recrpitous slopes or thew fit11 from cllffj. Soil or uther loose forms of earth may articiiate in such IandsIides; but-the material is usually composed chiefly of rock which becomes increasingyy shattered with the progress of the slide.

Earth-avalanches lsoil and rock falls1 were caused chieflv alone the sea-cliffs of the coast an the morning of the earthquake, tho'some also accurr~d on steep canyons withyn the zone of high intensity. On the mast the earth-avalanches were for the most part simply an exceptional incident in the normal process of cliff recession. Where the u land ofthe Coast Ranges approaches the shore, the horizontal corrasion of the waves maintains a steep sea-cli8: and the recession of the sea-cliff is effected bv the repeated occurrence of earth-avalanches due to the undermining by the sea, combined with the disintegriting action of atmospheric agencies. There are thus always upon the face of the cliff masses of earth or rock, the fall of which is imminent and may easily be preci itated by a severe shock of earthquake.

Along tge seashore immense landslides accwed, throwing vast quantities of earth and rock into the sea.

Lateral spreads and ground settlement .

9 Lawson and others, 1908, Besides these three types oflandslide, another ought perhaps to berecognized. This is the form ofsuperficial earth p. 386. movement which occurred in conseauence of the earthauake shack on the alluvial bottom-lands of manv

or. 11 may bc, toward an abandoned slouih, the lurch ~ s u d l l ~ h&ng accompilnied by a rotation of the prism: They arc dirtlnguished from all other forms of landslidui by occurring on perfectly flat pound and by the fact that-they arc appnrently referable directly nnd solely to the horizontal jerk of the eanh muvement during the earthquake shock.

10 Lawson and others, 1908, EARTH-LURCHES. Of the three kinds of landslides thus far referred to, the first two, earth-avalanches and p. 400. earth-slumps, occur quite commonly independent of earthquakes. Of the third kind, or earth-flows, the only

examples that have been presented are immediately connected in genesis with the earthquake of April 18, although it is conceded that sudden accessions of water to loose earth might arise in other ways and occasion earth-flows. As regards the fourth type, the earth-lurch [lateral s~readl it is difficult to conceive for i t anv other

. origin than an c.irthquake, since i i is caused dlrectlyby the f in r i~~~nta l jerk of the ground and canmot bc produced in any other way. [Authors in 1906 were n ~ t awareofthe liquefaction process.] In thcdctniledaccount of the distribution of apparent intensity, a brief nrcount d these superficial movemenu: ofthe ground has been

LIMITATIONS OF GROUND FAILURE DATA 7

TABLE 2.--Excerpted notes containing general description of the types, character, and locations of gmund failures associated with the 1906 San Francisco earthquake-Continued

Note Reference Quotation

Himmelwright, 1906, p. 21.

Lawson and others, 1908, p. 401.

/

Duryea and others, 1907, p. 258.


Hyde, 1906a, p. 705.

Carey, 1906, p. 299.



Lateral spreads and ground settlement-Continued

Greotdam;~ge was sustained by water work; in the rupture of matns, and the w reservoirs, plants and equlpmcnts. Elevated water tanks supported by steel and timber frrming were frequently wrecked. 'The railways also suffered cnorm,~us damage through d~;plnccmcnts of the roadbed and serious lnjurica to the bndgcs. The surface movements s e r e very much more apparent ln the cities and uwn5 where the alignment of the streets, rallwn tracks, pole lines,etc., wcre matrrinlly altered. Strect rails werescvered by tension i n some plnces and buckle~ar others. Large areas, constituting m.my acres, sctrlcd as much ns from ten to liflecn feet, badly diston~ng the buildrngs which drd not have deep foundations. -*- I t ir cvidcnt that the whole region ailcctrd moved eenerallv N 3 unit. and thin the sudden and iarrine motions had the effect oicauslnc local disturbances a d displ&ements wllerever the soil was soft, incoheknt and deep, as in the river bGtoms, artifically filled areas, etc. Marked disturbances and deformations of the softer material always resulted along the lines skparating a hard, compact material from one that was soit as, for example, the line of contact of the rock formations with the silt of the vallevs. ~. -~

~ e i o n d the zone i f the ~ i f t ,~&acks were observed a t many localities. These were most common on the hottom- lands of the streams, notably the Eel River (plate 138A, B), the Russian River (plate 139A, B), Coyote Creek (plate 140A, B), and other streams a t the south end of the Bay of San Francisco, Pajaro River (plate 141B), San Larehu, River, and the Salinas River. Many other smaller streams might also be mentioned. In these cases the' cracks were usually associated with the phenomena of lurching of the alluvial deposits, though many cracks also occurred where no such association was apparent. They were in nearly all eases found to be parallel or sub pa+alllel.G the nearest portion of the streamJr.e~h. They very commonly extended for several hundred feet, in some instances for sevel'al~hundred yard< and were characteristically arranged in linear series. The cracks in the series in some eases overlapt en echelon, and in others they were in groups of parallel cracks in belts a few hundred feet wide. In no case was there any suggestion that they were more than purely superficial phenomena.

Embankments-Embankments across marshes, or with soit strata underlying them, settled more or less. In same cases the settlement was vertical; in other cases there was considerable horizontal with the vertical movement.

Settlements ofthis character [embankments an tidal marshlands] and of more or less severity were common on all railroads operating about the Hay of San Francisco and its tiihutarics.

It is evxdenr that structures pcrta:nmg w railroads sun'ercd Severely in common with others. It is a -,ell-known fact that many cmbankmcnts were seriously distoned m nlignmrnt and were rc.dueed in elevation through srrrlcment duo to the vlbrarion. Landslides were not uncommon on hillsides and in curs where both rallronds and hrghwnys, prlnclpally the former, were located.

Thc disturbance had the effect oflowering the general lcvcl ofalluvial land and opening in it numerous crocks. In scveral instances in the Santa Clara Vellcy rvater plpcs in wells dug through the uncompnetcd and unconsoli- dnmd vallev sanda, mnvels and clnvs showed, aflc.r the shock. a foot ur more of the DIE above the ecncral ". e."-.".

Along rlvcr horwms andun valley flooos, panieularly where the ground water is abundant, structures werc much more susceptible to damage than s~milar structures founded on the firm rocks of the valley slopes. Thjs nu~arentlv hich intcnsitv nfthe shock in the vallcv lands was in oan duc to an actual slumoine ofthe ~ruund. d i c h wr iekd the buildings inde~endently of an; elastic vibration communicated to the& fGm the mound:

Draus-Brrdges.-Draw-brid es acrog the littic creeks and inleti around San Francisco Bay, heins geneF;lly qn f " ' . ' sol? ground, were offecte by a sl~ght movement of their pier&, in many cases resulting in the bri gc blndlng so that i t could not be opened until some repairs werc made.

' Ground cracks ' --

19 Lawson and others, 1908, Within the mne of high intensity no marshes and no bottom lands were seen which did not exhibit cracks, and I p. 74. regard their tracking as a general phenomenon. The elaborate cracking of a roadway across one of the marshes

seems saeciallv simificant. In the adiacent soft marsh close attention was necessarv to discover cracks. To a large exicnt th>y \;ere concealed by [lie vegetat~on, nnd i t is probable also ttlpt many which were opened during the earthquake agitation immedlstely closed agaln and werc practically ublltcrated by the weldlnp; of the mud. Hut the road embankment. bcinc free from \.ceetation and comooscd of com~arativelv rrcid and brittle matc- rial, retained all the cracks maze durine the &itation, and t h b served ta recard th"e tKoro shattering of an un&onsolidated formation when subjectd to s&ng vibration. (Plate 50.)

Another class of superficial cra& affected hillsides, penetrating only the coating of loose material- rleromnn~ed rock and talus. The eons~ieuous individuals of this t v ~ e are those that follow eantaurs. Along -.. ~~~ =.... ..... ~ ~~~~ ~~ ~.~~~~~ these there was often a notabl? w;dth ofcraek, accom anicd by d&ttling an thc down-hlll ~ i d e , and many cracks ofthiri type are still vlsrble. They arc in effect tRe heads of incipient landslides and mlght wlth equal propriety be described under another caption. They are numerous throughout the Rift belt and fairly nbun-

8 HISTORIC GROUND FAILURES IN NORTHERN. CALIFORNIA T R I G G E ~ D BY EARTHQUAKES

TABLE 2.--Excerpted notes containing general description of the types, character, and locations of ground failures associated with the 1906 San Franci.xo earthquake-Continued

Note Reference Quotation

Ground eracks--Continued



Gilbert, Humphrey, Sewell, and Saul&, 1907, p. 7.

Lawson and others, 1908: p. 73.


dnnt on jterp hills~des(nurth ofSan Francisco Hay] for more than a mile to the west. East ofthe Riti they are mconsplcuuus and believed to bc rare. Some of the best evnmples are on the northeastern slope of Mount Whittenberg, about a mile from the fault-trace, the locality being favorable for observstron because of the absence of forest.

Superficial cracks of a third type are connected with side-hill roads. (See plate 51.) In such roads there is usually a notch cut in the hillside and the excavated material is thrown outward so as to make an embankment. The roadbed thus consists in part of the natural formation and in part of an artificial and relatively loose embankment. In the loose material, and frequently along the line separating it from the firmer ground, cracks were extensively developed, often accompanied by evident settling of the outer bank. Their magnitude de- pended in part on the character of the material, but in large part also on the intensity of the earthquake. Where they were of such magnitude as to injure the roadway they were soon obliterated by road repairers, and elsewhere they tended to disappear in consequence of the traffic; but while they lasted they constituted an excellent age of intensity, and much use was made of them in districts where there were few buildings.

All thru thesif t there is associatibn of earthquake cracks with fault sags; probably half of the sags were bordered by such cracks on one side or the other, the crack usually following the line of separation between the side slope and bottom slope. In some instances there was a crack on each side of the sag, but more frequently on one side only. Where the sag eontained a pond the crack was usually present. With little or no exception these cracks exhibit downthrow on the side toward the sag. (See plate 52B.)

In the bottom-lands of creeks it happened a t many places that a slice of the alluvium was separated by a crack parallel to the bank and slid into or toward the stream. In some cases alluvium lying with a gentle slope adjacent to a marsh slid toward the marsh opening a crack along its u p r edge:

Mention has already been made of numerous hillside cracks which mar ed mc~plent landslides. In such cases the downward motion apparently began during the earthquake agitation, hut the momentum acquired was not sufficient to continue the motion after the earthquake stopt. In a very large number of these localities motion was resumed and landslides occurred during a period of excessive rainfall in the spring of 1907. (Plates 54A and 55A.) So far as mv observation goes, all of the landslides having this history were wet, the material usually florvh freely down the ilupe a& thin mud. CRACK^ All through the area of high intensity crack6 wrre made, and these wrre specially numerous near the fault trace. The cracks werc. also more numerous in solt alluvrum than in hard mound, but the number which ~~~~~-~ ~ - ~ ~ . . ~ - ~ ~ - ~-~ ~~-~ ~ - - ,-.-.x:. dee~lv ~enetrated the bed rock was~l&ge. Perhaps thls featurcls better expressed by saying that the bed rock wa; &ierally and profoundly sharterea, but without lmportatlt dislorntioi except on the old fault plane ---

At the surface the cracks had grcnt variety of expression. Somc were barely perceptible as partings; others caoed so widelv that onc mieht look down th+m several vards. Somc were mere ~ul l inas apart; uthers showed e ~ A ~ ~ ~ ~ - ~ ~~~~~ ~~ ~ ~

small differengal movemen& of the nature of faulting. Some were solitary: others, especiaily those exhibiting faulting, were in groups. Some straggled and bmnchea irregularly; utheffi~were nenrly stra~ght for hundreds of feet. Theoreticall , some cracks were prlmary as regards the earthquake and othc~.s secondary; that 1s to say. some wcrc enuseKdirect~v bv the oreexlstent strejses whlch oroduced the maln fault and others were cawed bv the waves co&tituting tke karthiuake.

Cracks.-In preliminary reports I have classified the earthquake cracks as primary and secondary, the primary being occasioned by strains which existed before the earthquake; and the secondary being caused by the earthquake. With the multiplication of observations this classification has become increasingly difficult, and I . now find it more convenient to group the cracks as superficial and deep, or superficial and bedrock.

Many of the superficial cracks are in alluvium. In the field excursions of April and May, 1906, they were seen in all alluvial formations within the RiR belt and for some distance on each side. The greater number appeared to be merely partings without vertical or horizontal throw. In general they were not parallel with one another nor were they otherwise systematically arranged, except that some of them were apt to occur along the boundary between alluvium and a firmer formation. They were rambling rather than straight and were oRen branched. They ranged in width from a fraction of an inch to several inches.

T** I t may be well to direct attention more particularly than has hitherto been done to the behavior of water contained in the alluvium of the river-bottoms. One of the most common phenomena in such situations was the expulsion of water in jets from apertures which suddenly appeared in the flat-lying ground. The water was u s i X l j T t h 7 G - i h 2 air far several feet; in some cases it was reported to be as much as 20 feet, and the ejection continued for several minutes aRer the earthquake. The continuance cf the ejection after the shock indicates that an elastic stress had been generated in the saturated ground, which thus found relief in the emulsion of the contained water or that there was a mavitational settling together of the material, which diminished the spaces occupied by water. The vents th;s established were Gery-numerous, and were in many instances closcly~spaced; mbrr fr&usntly a few to the acre, and oeensianally isolated. These vents \\ere cnsily recognmble for W L - L . ~ S and even months after the c.arthquake, in the, form ol'eratrrlets. The water in lupassagc to the surfaec broueht uo considerable aunntities of fin? sand. whlch, from its orsvailinclv llcht blulsh-pray color, was evidently deriGed from considerable depth, On theflood plain of t h i SalinasRiver, the sandwas recognized by the people of the neighborhood to bethe same ns that bf a stratum of sand pierced by wells at a depth of 80 feet. The craters were usually distinctly funnel.shape-d and were rimmed by a circular flat ridge of sand which. bv rt.a.ion of its lraht color. was in marked contrast to the surroundine surface. Thev varied in diameter from1 to perhaps l0'ket. In &me instance.; the funnels wrre several fee r~cep; in other;, the feeble actron in the closing stages of the eruption had caused them to f i l l up with sand. They were quite snalogouv ta the cra~er1et.s described and pictured in Duttan's account ofthe Charlejron earthquake. (See plates 142A, Band 143A, B.)

These craterlets occurred on practically all the saturated alluvial bottoms of the streams within the zone of destructive erects, and also onihc tidalmud flats ol'Tomales Bay. They are significant of the compression ta which such water-laden, incoherent formations were subjected by the passage of the carth.waves at the time of the earthquake or by the consequent settling of the ground.

DISTRIBUTION AND CHARACTER OF GROUND FAILURES 9

make postearthquake investigations; hence the ', amount and quality of information decrease with the

entiquity ,of the event. .For events prior to the 1906 sliock the record is very fragmentary. (5) In at least one instance, the results of a postearthquake investigation appear to have been intentionally suppressed. Con- cerning the 1868 earthquake, A. C. Lawson (1908, p. 434) noted

Shortly after the earthquake of 1868 a committee of scientific men undertook the. collection of data concerning the effects of the shock, but their report was never published nor can any trace of i t be found, altho some of the members of the committee are still livine. I t is ~~~ ~~ ~~

stated that rht report was supprest [src] hy the authorities, thru the fcar rhnt its oublicnrion !voulddamacc the rcoutarion ofthe clty. Our - knowledge of that earthquake is therefore not very full, and is eontained chiefly in the newspaper reports of that day.

The use of one word to describe two genetically different phenomena and ambiguous descriptions of damage are two additional factors that limit, o r at least confuse, the interpretation of the historical record. For example, many investigators of the 1906 earthquake referred to the fault rupture as "the crack." Because of

,-this usage, it is d e l t in many instances to distin- guish between cracks generated~by tectonic faulting and those generated by ground shaking. For this reason, nearly all cracks within the fault zoneare omitted from consideration in this report.

Some recorded descriptions are inadequate to differ- entiate whether damage to a structure was caused by deformation wholly within the structure or whether ground failure was also a factor. For example, a typical description might indicate that a building was shifted laterally during the earthquake. Such movement could have resulted from any of several sources including "walking" of the structure off of its foundations, collapse of underpinning, or ground failure.

In spite of the above limitations, the published reports provide an adequate sample of data for determin- ing the general type, character, and distribution of ground failures triggered by earthquakes in northern California. In several instances, the data are adequate for nearly complete delineation of ground failures in a particular area.

DISTRIBUTlON AND CHARACTER OF GROUND FAILURES

The 1906 San Francisco earthquake triggered ground failures at numerous locations throughout a 370-mi (600-km)-long segment of the Coast Ranges extending from southern Monterey County on the south to Eureka on the north (see fig. 1). Most of the failures tabulated in this report are from that event. Several other events for which the historical record contains

evidence of more than minor ground cracks include (1) the Oct. 8,1865, earthquake on the San Andreas fault, which generated ground cracks and sand boils in San Francisco (loc. 202), Santa Cruz (loc. 461, and Watson- ville (loc. 25), and small rockfalls and ground cracks in the Santa Cruz Mountains (loc. 60); (2) the 1868 earthquake on the Hayward fault, which caused ground cracks and lateral spreading in San Francisco (locs. 19%202) and cracks and sand boils along Coyote Creek at the south end of San Francisco Bay (locs. 149, 151, 153) and near Hayward (loc. 171) on the east side of San Francisco Bay; (3) two earthquakes two days apart in 1892, which triggered landslides in the mountains and ground cracks and sand boils in creek bottoms in a strip along the west margin of the Sacramento Valley between Vacaville and Capay (locs. 255259); (4) several moderate shocks in 1890, 1953, and 1954, which generated minor landslides in the Pajaro Gap area (locs. 28-30); (5) shocks in 1853, 1865, 1908, 1927, 1932, and 1954, which generated landslides, settlement, and ground cracks of up to moderate severity in the Eureka area; and (6) the 1957 Daly City earthquake, which generated landslides and ground cracks around Lake Merced (locs. 23Z242) and near Daly City (locs. 132-133). A full list of earthquakes causing ground failures is given in table 1.

Mapping of earthquake intensities has been useful in delineating areas of ground failure. Specifically, criteria used for mapping 1906 earthquake intensity are based in part on occurrences of ground failures and, hence, have aided in delineating areas in which ground failures occurred. Two intensity scales, quoted below, were used for mapping the 1906 event--the "San Fran- cisco scale" and the modified Rossi-Fore1 scale:

San Francisco scale (Lawson and others, 1908, p. 224): Grade A. Very violent.-Comprizes the rending and shearing of

rock masses, earth, turf, and all structures along the line of faulting; the fall of rock from mountain sides; numerous landslips of great magnitude; consistent, deep, and extended fissuring in natural earth; some structures totally destroyed.

Grade B. Violent.-Comprizes fairly general collapse of brick and frame buildings when not unusually strong; serious cracking of brick work and masonry in excellent structures; the formation of fissures, step faults, sharp earnpression anticlines, and broad, wave-like folds in paved and asphalt-coated streets, accompanied by the ragged fissuring of asphalt; the destruction of foundation walls and underpinning structures by the undulation of the ground; the breaking of sewers and water-mains; the lateral displacement of streets; and the compression, distension, and lateral waving or displacement of well-ballasted street-car tracks.

Grade C. Very strong.-Comprizes brick work and masonry badly cracked, with occasional collapse; some brick and masonry gables thrown down, frame buildings


1 lurched or .listed on fair or weak underpinning I The "San Francisco scale" was used onlv for mauuine A. -

intensities in San Francisco City and County (fig. 5). The highest intensity grade, grade A, is based almost exclusively on the occurrence of fault ruptures, large E

l landslides, and deep cracks. Grade B is based partly on :( Grnde D.

1 chimneys; cracks i;masonry and brick work; cracks I the occurrence of severe structural darnaee and uartlv

structures, with occasional falling from underpinning or collapse; general destruction of chimneys and of masonry, brick or cement veneers; considerable cracking or crushing of foundation walls.

Strone.-Comorizes eeneral but not universal fall of

- - 1 1 in foundation walls, retaining walls, and curbing; a I On the occurrence of mound failures of lateral- few isolated cases of lurching or listing of frame 1 buildings built upon weak underpinningstrudures.

Grade E. Weak.-Camprizes occasional fall of chimneys and I 1 damap-e to plaster, partitions, plumbing, and the I like.

Modified ~ossi- or el scale (Lawson and others, 1908, - ,C,\. ! p. IVL,. 8

In the first blace, the scale upon which the gradation of intensity is indicated, tbdt known as the Rossi-Fore1 scale, is more or less arbi- trary. At the outset of the inquiry, the Commission revised and simplified thfs scale somewhat, with the object of adapting it for general use, and its present form, as amended by the Commission, is as follows: I

I. ~e!!eeptible, only by delicate instruments. 11. ~ e b slight, shocks noticed by few persons a t rest.

111. ~ l i k h t shock, of which duration and direction were noted Gy a number of persons.

IV. ~ d d e r a t e shock, reported by persons in motion; shaking of I

moveable objects; cracking of ceilings. V. d a r t shock, generally felt; furniture shaken; some clacks

&opt; some sleepers awakened.

- spreading and ground settlement types. Grades C through E are based entirely on damage to constructed // works. Hence, zones of grade A and B intensity gener- - ally delineate areas where faulting and ground failures

'

disturbed the ground surface. Areas zoned grades C through E delineate areas with varying severities of structural damaee but with a eeneral absence of sie- - - - nificant ground failures. Hence, areas zoned A and B ,! generally coincide with zones of ground failure in San Francisco, whereas intensity grades C through E delineate areas where few significant ground failures occurred.

The modified Rossi-Fore1 scale was used to map 1906 earthquake intensity throughout the Western United States. Criteria used to assign intensity grades I-IX on the modified Rossi-Fore1 scale do not include ground failure effects. T~.~highe_st,grade(X),ho.weev.ee~,.is.based almost exclusively on occurrences of fault rupturing, . . . . . . -- . - - la;ids_kd_e_s,..and deep .. ground ..~.. cracks. . On the maps prepared by the 1906 investigatordfie. 6) (Lawson and

Clocks; some window glass broken. VII. v ib~ent shock, overturning of loose objects; falling of plas-

{er; striking of church bells; some chimneys fall. VIII. Fall of chimneys; cracks in the walls of buildings.

VI. ele ere shock, general awakening of sleepers; stopping of

IX. partial or total destruction of some buildings. X. ~ r k a t disasters; overturning of rocks; fissures in surface of

, I earth; mountain slides. I

- - . . / others, i908. atlas. D. 21-23). onlv a narrow zone alone

It is aDDarknt that the scale leaves room for wide variation in the . . personal eqdation. Different reporters interpret the same experi-

1 ences and the same phenomena differently. It was also found that in the peripher$ of the region affected, where the earth waves were of slow period, ipendent objects and liquids were more sensitive indic- ators of eartA movement than direct nerce~tion bv individuals. altho

., " - the an ~ n d r e a s f&t is mapped as intensity grade X. This zone generally coincides with the zone of 1906 fault ruptures. Other areas where severe ground failures occurred, such as along the Salinas kiver, were given a lesser intensity, indicating that averaging of intensities within a given area probably occurred durine comuilation of the man. For delineation of areas - subjected to ground failure, such averaging reduces the usefulness of the map to almost nil because it obscures the data and falsely infers, from direct reference to the scale, that major ground failures did not occur in areas . .

the latter is iplaced first in the scale. I characterized by intensities less than X.


FIGURE 5.-1906 earthquake intensity map prepared for San Francisco County using San Francisco intensity scale (aRer Lawson and others, .. .. . . ~ .:. ..

1908, map no. 19).


FIGURE 6.-1906 earthquake intensity map for Western United States based an modified Rossl-Fore1 scale (aRer Lawson ...- and others, 1908, map no. 23).

DISTRIBUTION AND CHARACTER

MONTEREY BAY COUNTIES REGION

Monterey and San Benito Counties, the southern parts of Santa Cruz and Santa Clara Counties and the western parts of Fresno and Merced Counties form the Monterey Bay counties region (pl. 1 and table 5, locs. 1-44; figs. 7-17). (Regions in this report were selected largely on the basis of available map sheets and amount of data for any given area.) This region has been shaken in historic times by several moderate- to large-sized earthquakes; however, only two events, the October 8,1865, shock for which we have but fragmentary information, and the 1906 shock, have produced more than minor local effects. Hence, the discussion in this section is limited almost exclusively to ground failures caused by the 1906 SanFrancisco earthquake. A summary of statements excerpted from reports on the 1906 shock containing generalized descriptions of ground failures in the Monterey Bay counties region is reproduced in table 3. Specific descriptions of individual failures are contained in the descriptions of failures (table 5, locs. 1-44).

Plates 1 and 2 show that the density and severity of ground failures generated by the 1906 earthquake generally decreased with increasing distance from the

j causative fault rupture (the southern limit of which ; was near San Juan Bautista). Thus, the density and

severity of failures decreased southward from San Juan Bautista. The southernmost reported failure was slight settlement beneath the Bradley, Monterey County, railroad station (lac. 1). Bradley, not shown on plate 1, is located near the Salinas River, 12 mi (19 km) southeast of San Ardo, which is located near the southern edge of the map.

On a local basis, geologic setting had a greater effect on the density and severity of ground failures than distance to the ruptured fault. Areas with the greatest .. ,.. . density and s t y c t ~ " of ground failures included & I lying -- alluvial deposits along the Salinas and Pajaro -- .. - -. , Rivers andbeachand dune .. . . d.eposi$,necth,e. .. mouths of these rivers. In fact, one investigator stated that the Salinas River valley was "fissured and disturbed more than any other district in the state" (note 5, table 3, this report; Gilbert and others, 1907, p. 133).

The principal .~ ,.... failure ...., types in the riverv_aLep were ~. r slumping of ~ t r e a r n b a n k ~ ~ ~ l l'at&lspreading of7iHt- V - . .

land~_tow.ard~chann_e~ssina,m_anney,s~,m~lar,~o. that-described in reports from the 1964 Alaska earthquake (Kachadoorian, 1968; McCulloch and Bonilla, 1970).

I! These failures were accompanied by considerable : I :!, ground cracking and differential settlements and by

,. i ; the pervasive eruption of sand boils. The sand boils are j ! evidence that liquefaction played a major role in these . , ..failures. Lateral displacements associated with lateral

OF GROUND FAILURES 13

spreading were as large a~d&&4&7-m). The largest displacements were no&-near Monterey Bay at and north of Moss Landing (locs. 19, 21). Inland along the Salinas and Pajaro Rivers lateral displacements as large as 10 ft (3 m) were common. These movements considerably damaged bridges and pipelines that crossed the rivers and highways and railroads that paralleled the rivers. Photographs of 1906 ground failures along the Salinas and Pajaro Rivers and the damage they caused are shown in figures 7-10 and 12-17,

A geotechnical section across the Salinas River in the zone of 1906 ground failures (fig. 11) was compiled from foundation investigation borehole logs for the State Highway 68 bridge over the river. This bridge is located 0.5 mi (0.8 km) upstream from a bridge that was severely damaged during the 1906 shock (fig. 10, loc. 12). The geotechnical section shows several layers . of loose to dense sands, sandy silt, and clay in a com- plex configuration extending to depths as great as 80 ft (24 m). The area is characterized by a high water table that ranges in depth from several feet beneath the God plain to the ground surface at the river. The evident cause of ground failure at this location was liquefaction within a loose granular layer below the water table (Youd and Hoose, 1976).

Effects similar to those along the Salinas and Pajaro Rivers, but of much lesser extent and severity, also occurred along the San Lorenzo Fiiver (locs. 43,44) and Soquel Creek (locs. 41,42) in and near Santa Cruz and Capitola, respectively. These latter failures caused no significant damage.

Buildings and other works sited on deep unconsolidated deposits generally were damaged more. than those sited on shallow unconsolidated deposits over bedrock. This was true even at localities where ground failure was not a factor. For example, A. S. Eakle (Lawson and others, 1908, p. 296) reported that "the town of Salinas suffered greater destruction than any other place in the county." Nevertheless, no evidence was found during this study of any significant ground failures in the city of Salinas during the 1906 event. Most of the older section of Salinas is located in the Salinas River valley, which is underlain by unconsolidated Holocene sediments to considerable depth. Amplification of bedrock ground motions by these sediments likely led to the great damage. Great damage was also reported from Del Monte and the Pacific Grove Light House (A. S. Eakle in Lawson and others, 1908, p. 291, 343), Santa Cruz (Lawson and others, 1908, p. 3431, Hollister, and other parts of the lower Santa Clara valley (Lawson and others, 1908, p. 28& 290) as well as parts of the San Joaquin Valley, particularly the area surrounding Los Banos (G. F. Zoffman, in Lawson and others, 1908, p. 316, 345).


Local geology may have been an important factor in amplifying or modifying ground motions in these areas, which led to greater-than-normal damage. Ground failures, however, were apparently not a factor.

Other than some cracks along steep bluff faces, upland alluvial terrace and eolian deposits were apparently unaffected by ground failures during the 1906 earthquake. This conclusion is supported by notations and maps (fig. 6) showing that damage was less in the upland areas than in the river valleys and by the absence of ground failure reports from the upland areas, which is considered to be positive evidence because several investigators traveled through those areas and most likely would have noted any significant ground failures. Some specific notes do show an absence of ground failures in some areas. For example, G. A. War- ing (Lawson and others, 1908, p. 292) noted that "Cas- troville [loc. 171 being on solid ground was unaffected"

and A. S. Eakle (Lawson and others, 1908, p. 292) reported that "On the road eastward to Salinas from Del Monte [loc. 121, no visible signs of the earthquake were encountered until the Salinas River was reached."

The mountains in the Monterey Bay counties region apparently were only slightly affected by ground failures during the 1906 temblor. The largest failures reported were landslides near the fault trace west of Chittenden (loc. 31) where several large rockfalls and debris slides filled the lower part of the canyon. A linear array of landslides occurred near the west margin of the San Joaquin Valley (loc. 71, which led some investigators to speculate that there might have been sympathetic movement on a fault in that region. How- ever, no evidence was found to support this speculation (G. D. Louderback in Lawson and others, 1908, p. 319). Many small landslides occurred in the mountainous areas, including a dislodged boulder that crashed through a house, killing one man (loc. 38).

TABLE 3.-Excerpted notes containing general descripLions of ~ - ground . ~~ failures in the Monterey Bay counties region

Note Rearen"" Quotation



3 Duryea and others, 1907, P. 311.


5 Gilbert, Humphrey, Sewell, and Soul&, 1907, p. 133.


Effect upon structures, objects, etc. (G. A. Waring).-It is remarkable how closely the disturbance followed the river channel throughout the Salinas Valley; 2 or 3 miles away from the stream on both sides the intensity was very slight. Southward up the valley the shock gradually lessened, and rapidly died out in the foot-hills on either side.

I Text continued on pace 23 1


FIGURE 7.-Damaged rails and pulp flume a t Spreckels sugar mill as a consequence of lateral spreading during 1906 earthquake (loc. 11). A. Pulled apart rails showing 3 ft (0.9 m) of differential lateral movement. (Photograph by A. C. Lawson, courtesy of The Bancroft Library, University of California, Berkeley.) B. Displaced pulp flume-aption an photograph states "wrecked pulp flume and leaning tower; ground moved 4 ft [1.2 m] south." (Photograph courtesy of K. A. Meserale, Menlo Park, Cali- fornia.)


FIGURE 8.-Barley field "car Spreckels drsrupted by slumprng and lateral-sprcoding failures ildc. 12). I'reviously published in Lawson and others (1908, ~ 1 . 137,\1 wirh captlun "Lurching of mound toward Sll lnas Iiiver, with consequent collnpse." \Photo~.;rph by J.C. Bron- . . ner, courtesy of Stanford University Archives.)

DISTRIBUTION AND CHARACTER OF GROUND FAILURES

FIGURE 9.-County road along Salinas River, south of Salinas, disrupted by slumping and lateral spreading (loc. 12). (Photograph courtesy of K. A. Meserole, Meulo Park, California.)

FIGURE 1 0 . S o u t h terminal pier of bridge over Salinas River 4 mi (6.4 km) south of Salinas (loc. 12). Surficial deposits shifted about 6 ft (2 m) toward the river. (Photograph by J. C. Branner, egur\tesy of Stanford University Archives.) . - ( \ \

.y f i q > . ,

" [) .-


+TO MONTEREY

0 10 20 30 40 50 METERS

FIGURE 11.-Geotechnical section across the Salinas River at State Highway 68 bridge; (lac. 12) 0.5 mi (0.8 km)


TO SALINAS

0 Sand

El 0 clay Interbedded sand

and chy

Water table in borings Approximate water table Standard penetration- at time of drilling blowslft (January 1963)

upstream from the bridge damaged during the 1906 shock (fig. 10) (data from Division of Highways, 1964).

20 HISTORIC GROUND FAILURES IN NORTHERN CALIFORNIA TRIGGERED B y EARTHQUAKES

FIGURE 12,Damage at Moss Landing caused by lateral spreading (loc. 191. A. Damaged railroad bridge. Photograph previously published in Lawson and others (1908, pl. 135A) with caption "Lurching of ground toward Salinas River, to left, carried piles from beneath bridge timbers and caused bridge to collapse. Displacement 9 feet [2.7 m]."B. Displaced building. Photograph previously published in Lawson and others (1908, pl. 134Al with caption "House, tree, and fence moved 12 feet [3.7 m] by lurching of ground toward Salinas River." (Photographs by A. C. Lawson, courtesy of The Bancroft Library, University of California, Berkeley). C. Ground ruptures in Moss Landing between Monterey Bay and old Salinas River. View eastward toward bluffs between Elkhorn and Moro Cajo sloughs. (Photo- graph courtesy of Monterey County Historical Society, Inc., Salinas.)


FIGURE 13.-Ground failure scarp in a former community called Chinatown located near south bank of the Pajaro River across from Watsonville (lac. 25). (Photograph courtesy-of Pajaro Valley Historical Association, Watsonville.1

~ ~. . . . . - . . . .. .

FIGURE 14.-Graben and damaged buildings caused by lateral spread near the Pajaro River a t the foot of Marchant Street in Watsonville (lac. 25). (Photograph courtesy of Pajara Valley Historical Association, Watsonville.)


FIGURE 15 .S lump scarp and sand boil near Pajaro River (lac. 27). Similar photograph previously published in Lawsan and others (1908, pl. 141B) with caption "Secondary crack, with drop of 7 feet, in alluvial flood-plain of Pajaro River." (Photograph by Livennon, courtesy of The Bancroft Library, University of California, Berkeley.)

FIGURE 11.-County road bridge over the Pajaro River near Chitten- FIGURE 16.-Sand boil near Watsonville. Part of this photograph

previously published i n Lawson and others (1908, pl. 143B) with den (loc. 30). Abutment displaced and fractured by lateral spreading of sediments toward the river channel. (Photograph by Liven-

caption "Craterlets near Watsonville" (lac. 27). (Photograph by J. non, courtesy of The Bancroft Library, University of California,.

C. Branner, courtesy of Stanford University Archives.) Berkeley.)


SAN FXANCISCO BAY COUNTIES REGION

SANTA CRUZ MOUNTAINS

The Santa Cruz Mountains comprise the northern part of Santa Cruz County and the western parts of Santa Clara and San Mateo Counties (pl. 2 and table 6, locs. 4kL135; figs. 18-25). Ground failures in the form of hillside landslides, flows, slumping of streambanks and ground cracks, both on the hills and in the creek bottoms, were numerous and widespread effects of the 1906 San Francisco earthquake in this area. The most common damage caused by these failyres was to highway and railroad grades and to bridges. Rockfalls and dry sand flows along the coastal bluffs were particularly disruptive in this respect. For example, the ocean shore railway grade between Lake Merced and Mussel Rock (locs. 131, 132,133, fig. 241, then under construe- tion, was a1 ost entirely destroyed for a distance of 3 mi (5 km). S , mewhat similar landslides were triggered in this sa , e area during the 1957 Daly City earthquake. 4

Two catastrophic rockfalls occurred in the southern Santa Cruz Mountains. One on Hinkle Creek, a branch of Soquel Creek (loc. 501, buried the Loma Prieta Mill killing nine men, and the other on Deer Creek (loc. 74, fig. 19) became a rock avalanche that moved about 0.25 mi (0.4 km) down a narrow canyon destroying a shingle mill and killing one man.

A number of flow failures were triggered in the Santa Cruz Mountains by the 1906 earthquake (locs. 110-114, 135; figs. 20-22, 25). These failures occurred in wet surficial materials, anct many were associated bith conspicuous amounts of surface water. In some instances these flows traveled considerable distances at relatively high velocities (for example loc. 135). In other instances the flows traveled rather slowly (for . example loc. 113).

. Because the flows were generated in wet unconsolidated' sediments, generally as a consequence of liquefaction, precipitation records for the Santa Cruz Mountains for the winter preceding the 1906'shock are relevant. Monthly and daily rainfall data for San Francisco, Santa Clara, and Santa Cruz (figs. 2 4 ) i show that precipitation was unusually heavy during the winter, particularly in March, and that a17_dday rain-frekp-eriod p~e~d_e.d-th.e-sh~k. Had hhe shock occurred when ground water conditions were signifi- cantly different, such as during the dry season of the

! year, the number of flow failures most likely would have been greatly reduced; on the other hand: had the shock occurred when the ground was even wetter, such as during or immediately after a major storm sequence, even more flows might have developed.


SAN FRANCISCO BAY, SANTA CLARA VALLEY, AND EAST BAY HILLS AREAS

Included in the San Francisco Bay counties region are Alameda County, the southern part of Contra Costa County, and the eastern parts of Santa Clara and San Mateo Counties (pl. 2 and table 6, locs. 136182; figs. 26-29). (San Francisco City and County is considered separately in the next segment of the report. Locs. 183-192 are discussed in the section on the "North Bay Counties Region.") The most common failures on the alluvial plain surrounding San Francisco Bay were lateral spreads, slumping of streambanks, ground setr- tlement, and ground cracks (figs. 2628). These failures were located chiefly along stream channels and margi; nal to San Francisco Bay. Lateral movements of 2 6 ft (0.6-1.8 m) were reported in the Colma Valley (loc. 1361, on the San Bruno Marsh near Baden (loc. 137), along Coyote Creek north of San Jose (locs. 149, 150), a t a point on the railway line between Niles and San Jose (loc. 1621, and along Alameda Creek (loc. 170). These failures were mostly in sparsly populated areas; however, they caused considerable damage to railroad and highway grades and to bridges. Similar types of failures occurred along the lower reaches of Coyote (l'ocs. 149,151,153) and Alameda (loc. 170) Creeks during the earthquakes of 1868 and 1906.

Figure 29 shows a geotechnical section across Coyote Creek at the State Highway 237 bridge. This bridge is very near the site of the old bridge (loc. 149) that was damaged by lateral spreading during the 1906 temblor. The section shows that a loose granular layer just below the water table extends at least 800 ft (240 m) westward from the creek. Cracks and sand boils were reported as far as 2,000 ft (600 m) west of the creek after the 1906 shock (lac. 149). Liquefaction in this or similar granular layers was most likely responsible for the sand boils and ground failures that occurred in that area.

Ground settlements of up to 2 ft (0.6 m) occurred around two well casings 4 mi (6.4 km) apart (locs. 147, 148) near the south end of San Francisco Bay. Flow from these and other wells in the vicinity (locs. 146, 149) was temporarily increased. Settlement of highway and railroad fills was also reported from several locations near the margins of San Francisco Bay (locs. 138, 141; notes 11-18, table 2).

No significant ground failures were reported on late Pleistocene and-mxlc-Holocene alluvial fan deposits a t points well removed from active stream channels. These older, more consolidated and denser materials (Youd and others, 1975) apparently resisted the shaking of the 1906 event without significant yielding. This inference is supported by several specific notations of lack of ground movement. For example, Derleth (in


Jordan, 1907. D. 188) stated that "San Jose's water I The eventual construction of the streets in the lower section of the . A ~ ~

works,like that of ~ a n t a Rosa, was not injured; its sewers were left intact, showing that there was no unequal displacement of the ground [loc. 1571." Other statements showing. lack of ground failure are listed

city caused the existence of many blocks surrounded on all four sides by high earth embankments, undrained, unsightly, with many stag- nant pools, and gradually filling with rubbish and trash of all kinds. Captain Folsom was the first to fill in one ofthe water lots, an expen- sive dece of work on California Street west of the ~ r e sen t site of the -

under locations 144, 156, and 164 in the descriDtions of I ~ a n i of California. Despite the cost, i t was recognized as a valuable

severe. Ground cracks were generated at several loci- I cubic yards per day. As the shovel could work profitably only in sand

ground failures (table 6). The lgo6 earthquake reports indicate that ground

failures in the hills east of Sari Francisco Bay and the Santa Clara Valley were few in number and not very

tions north of Livermore (loci. 166, 167, 180). In addition several shallow debris slides occurred along a road in the hills east of San Jose (loc. 160), and an acceler-

undertaking and others speedily followed. James Cunningham realized this was a jab for a steam shovel (or "steam paddy") and had one brought in by steamer. From 1852 to 1854 and from 1859 until 1873 a steam shovel was working constantly, loading into small railway cars and dumping in the bay, moving more than fifteen hundred

ated movement of an already active slide occurred east of San Pablo (loc. 179).

SAN FRANCISCO CITY AND COUNTY

Because of the considerable amount of damage that occurred in San Francisco (pl. 3 and table 7, locs. 19% 248; figs. 3LL54) and the greater development of that community compared with the surrounding region, more thorough 1906 postearthquake investigations and more quantitative reports were prepared than for most surrounding areas. This was generally true for earthquakes in 1865 and 1868 as well. Ground failures in San Francisco have been limited mainly to areas underlain by filled over marsh and bay mud deposits, filled-in ravines, loose sand deposits near Lake Merced, sand dunes, and steep slopes. Locations of failures are shown on plate 3 and for the downtown and waterfront sections on figure 30. General notes describing these failures are listed in table 4.

Before examining the nature of seismically triggered ground failures in filled over marsh and bay mud deposits, a brief review of the methods and materials used in constructing the fills is provided from Brown and others (1932, p. 29):

Many difficulties were experienced in grading the streets in the swamp areas. Hittell [I8781 states: "When streets were first made the weieht of the sand Dressed the eat down so that the water stood

and where there were comparatively long hauls, a large portion of the work was moved more economically by horse and cart even though a man with a horse and cart was paid $15.00 a day.

There are no official firmres on the amount of material moved. Hittell (1878) assumed atransfer of 21,000,000 cubic yards, while Bancratt (1882) estimated this to be 22,000,000 cubic yards. These figures are probably conservative.

Three major ground failure zones have been identified in the filled areas of San Francisco. These zones are designated here as (1) foot of Market zone, (2) south of Market zone, and (3) Mission Creek zone (fig. 30; pl. 3). These zones are generally congruent with three conspicuous zones mapped as intensity grade B after the 1906 earthquake (fig. 5). The most common ground failure types in these zones were lateral spreads and differential ground settlements. Because of the critical locations of these failures, they were responsible for considerable damage including the breaking of several major water pipelines that, in turn, left the city largely defenseless against the conflagration (fig. 49) that followed the 1906 earthquake. (See notes 14-19, table 4.)

In the foot of Market zone, settlements as large as 4 ft (1.2 m) occurred during the 1906 earthquake (loc. 193). During the 1868 earthquake settlements of 1-2 ft (0.3 m-0.6 m) were reported (locs. 199-2001, and some settlement also was reported during the 1865 earthquake (loc. 202). Near the waterfront, permanent lateral movements as large as 2 ft (0.6 m) developed during the 1906 shock (loc. 193, fig. 31). The magnitude of these displacements decreased with distance from the waterfront. Some horizontal movements also apparently occurred in the foot of Market zone in 1868 (locs.

where the surface-was dry before. Sometimes the sand brake 1 198, 200). Before a thorough investieation could be

. - - ~ ~ ~ ~- ~ ~ ~~

~= ~ ~. .-.. .---, ~ ~~~ ... .... ~- =-- -- - --, between the notice and inspection, the sand had sunk down six or I and by workers during cleanup operations.

through, carrying the peat down under it, ieaving nothing but water or thin mud near the surface. More than once a contractor had put on enough sand to raise the street to official grade, and gave notice to the Citv Eneineer to insoeet the work. but in *he lnnse of 2 dav

eight feet; and, when a t last a permanent bottom had been reached ( A geotechnical section beneath Market Street from

- made, evidence of 1906 ground failures and most of the consequent damage in the foot of M~~~~~ zone Were by the fires that devastated the area

. . . . houses and fences built upon itwere carriedaway from theirbrigina1 approximately 20 ft (6 m) thick near the waterfront positions and tilted up a t singular angles by the upheaval." 1 and thins with distance inland, feathering out near

the heavy sand had crowded over the light peat a t the sides of the street and lifted it up eight or ten feet above its original level, in muddy ridges full of hideous cracks. Not only was the peat crowded UD by the sand in this wav. but i t was-also ~ u s h e d sidewise. so that

the bay to Second Street (fig. 32) shows that a layer of fill mostly ofloose fine sand with some rubble particles the foot of Market 'One. The is


Sansome Street. In March-July 1964, the ground water level was at a depth of about 8 ft near the waterfront and increased in depth to about 18 ft at Sansome Street. The ground water level was probably at about the same depth in 1906. Beneath the fill are layers of

' soft silty clay (bay mud) with some sand lenses. These sediments are in turn underlain by more firm materials. Liquefaction within the sand fill or an underlying sand layer is the only tenable explanation for the ground failures that developed in this area (Youd and Hoose, 1976). One evidence that liquefaction occurred in the foot of Market zone during the 1868 earthquake was the ejection of water from cracks and fissures (loc. 201). These ejections were probably a form of sand boils. No sand boils were reported in the foot of Market zone in 1906. However, some could have occurred only to be destroyed during the fire and ensuing cleanup operations ~ orfor-.someother reason were not reported.

The\south of Market zondlies in an area of filled-over marshland extending from Rincon Hill near Fourth and Brannan Streets westward approximately 1 mi (1.6 km) to near Market Street (locs. 205-212; figs.

,' 3%36). Differential settlements in this zone were as . 7: large as 5 ft (1.5 m), and lateral displacements as large

b ' ~ L,: as 6 ft (1.8 m). The ground failures in that area were -A remarkable in two respects. First, the slope down the

I . ' . , . ,.,

a ' . , . axis of the zone (from near Eighth and Mission Streets 0' to Fourth and Brannan Streets) was only 0.8 percent

/ ;: (0.5"). Second, the lateral movement was not into a free face, but rather into Rincon Hill, a sandstone outcrop

, . , .

(Schlocker, 1974). At the head of this lateral spread, extensional features such as open cracks and pulled- apart rails, sidewalks, and curbs (loc. 205) were common. Where the failure butted into Rincon Hill, compressional features such as buckled rails and curbs indicated that the lateral displacement was absorbed by compression.

The U.S. Post Office Building at the corner of Seventh and Mission Streets (loc. 210, fig. 35) is astride the north margin of the south of Market zone. During the 1906 earthquake the ground in front of the Post Office settled 4 or 5 ft (1.2 or 1.5 m) and moved laterally about 2 ft (0.6 m), damaging the stone skirting around the base of the building (fig. 35A, C) and pulling the sidewalk apart a t the construction joints (fig. 35B). The building, which is apparently founded on a grillage foundation carried down to a firm granular layer (Gil- bert and others, 1907, p. 97-98), sustained little structural damage and is still (1977) in usei

A geotechnical profile across the south of Market zone at the latitude of the James Lick Skyway (fig. 36) shows a 5-8-ft (1.5-2.4-m)-thick layer of rubble fill in the ground failure area. The rubble is underlain by a 7-114% (2.1-3.4-m)-thick layer of generally loose sand


that is also probably artificial fill. Underlying the sand is a deep'layer of soft peaty clay (bay mud). The water table in March 1952 was only a few feet deep across most of this section. Liquefaction within the loose sand layer is the only tenable explanation for the ground failures iRthis area (Youd and Hoose, 1976).

The l ~ i ~ s i o n Creek which apparently contained several ground failure segments, extended up the sinuous former channel of Mission Creek from Old Mission .. Bay to near the intersection of 19th and Guerrero Streets (locs. 21P217; figs. 37-51). Settlements as large ad6 ft'(1.8 m) and lateral movements at least as large ask6-ft,?l.8 m) occurred at several locations within this zone. The average slope from 19th and Guerrero ,,

Streets to the freeway is 0.6 percent or 0.3". Ground failures within this zone were responsible for some serious and spectacular damage, much of which is well recorded on photographs.

Figure 37 is a schematic diagram of present streets in the lower part of the zone showing approximate locations and directions from which the photographs in figures 3 5 4 1 were taken. These photographs show southwestward lateral spreading across both Ninth and Dore Streets between Bryant and Brannan Streets. The lateral spreading did not extend as far 'south as 10th Street, where there was but little evidence of ground failure (loc. 214).

Figure 42 is a schematic diagram of several streets in the midsection of the Mission Creek zone showing approximate locations and directions in which photographs in figures 4%47 were taken. These photographs show the magnitude, location, and character of the lateral-spreading ground failure in this area. Lateral movements of up to several feet developed down the axis of the zone and in some areas toward the axis, causing compressional deformation at some locations (figs. 43, 44, 47) and extension features at other locations (figs. 45, 46).

The damage at Valencia Street was the most catastrophic of any that occurred in the Mission Creek zone (loc. 216; figs. 48A, 48B). Vertical and horizontal displacements here were both as large as 6 ft (1.8 m). Two main arterial water pipelines laid beneath the street were severed by the ground failure cutting off the water supply to a major part of the city which was soon to be in flames (fig. 49). Also, the catastrophic collapse of the four-story Valencia Street Hotel (loc. 216; fig. 48A) occurred at this location. This collapse may have been at least in part a consequence of the large ground movements that extended beneath the structure. Tens of people were killed in the collapse and the ensuing consumption of the building by fire.

At the head of the Mission Creek zone, a substantial three-story brick building (fig. 50) was carried laterally

TABLE 4.-Excerpted notes containing general descriptions of ground failure ond consequent pipeline breaks in Sun Francisco

26 HISTORIC GROUND FAILURES IN NORTHERN

6 ft (1.8 m) along with the curb, walk, and street in front of the building (loc. 217). There is no evidence indicating that lateral spreading continued up the old Mission Creek channel beyond this location.

A geotechnical section across the Mission Creek zone at Mission Street (fig. 51) shows a layer of very loose fine sand fill underlain by layers of soft clayey sand and soft silty sand, which are in turn underlain by alternat- ing layers of firm clean clayey sand. In February 1964 the water table was as shallow as 5 ft (1.5 m) beneath the ground surface in that part of the section where the 1906 lateral-spreading failure took place. Liquefaction wtihin the loose sand fill or possibly the soft silty sand layer beneath the fill is the evident cause of ground failure in this zone (Youd and Hoose, 1976).

Two ground failures in filled ravines, though small in size, produced rather spectacular results. One near the intersection of Vallejo Street and Van Ness Avenue (loc. 221, fig. 52) was characterized by differential settlements as great as 2 ft (0.6 m) and lateral displacements as great as 3 ft (0.9 m). The other, on Union Street between Pierce and Steiner Streets (loc. 222, fig. 53), had vertical and lateral displacements as great as 10 ft (3 m) and moved down a rather steep slope into an unfilled vacant lot.

Several lateral spreads and rotational slumps, some of which were converted into flow failures, occurred around the shoreline of Lake Merced during both the 1906 and 1957 earthquakes (locs. 232, 242; fig. 54). These failures caused considerable damage to highway embankment and bridge structures around and across

Note Reference quotation

CALIFORNIA TRIGGERED BY EARTHQUAKES

the lake. Liquefaction within natural and artifically placed sand surrounding and beneath the lake has been identified as the cause of many of the 1957 failures (Bonilla, 1960) and is the probable cause of the 1906 failures.

After an earthquake in 1852 fissures were found between Lake Merced and the Pacific Ocean (loc. 244) through which the waters of Lake Merced were flowing into the sea. It is unclear whether these ruptures were generated by an earthquake or by other factors such as previous heavy rain storms that may have caused over- topping of or piping through the natural embankment between the lake and the ocean (Soul6 and others, 1854).

The sand dune section of western San Francisco was very sparsely developed ,in 1906. As a consequence, only fragmentary descriptions of ground failures in that section are available from the 1906 reports, and some of these descriptions are vaguely stated. The reports indicate that some areas of instability developed near the ocean (locs. 246, 247) and some cracking and lateral spreading occurred farther inland (locs. 230, 243). Liquefaction probably contributed to the development of these failures as evidenced by the eruption of sand boils a t several locations (locs. 243, 247).

Several hillside landslides occurred on the steeper slopes in San Francisco during the 1906 event (locs. 218, 22G229). These failures were responsible for structural damage to the Cyclorama, a building in Golden Gate Park (loc. 228), and a retaining wall at Laguna Honda reservoir (loc. 229).

1 Lawson nnd others, 19Ud. It is evident that the intcnsaty vanes with the grulogy, or with the areal distribution of rucks and soils p. 253. The areas that suffered most scvcrcly were those upm filled ~ r d ~ n d .

Arras uoon marsh" eround showed destruotlve effects ilmllar to urr~f ic~el filled land Next in;ntensity &as of filled land are those w o n incoherent sands. The damage in sandy areas was

2 Jordan, 1907, p. 238.

3 Hall, 1906, p. 32.

4 Carey, 1906, p. 297.

5 Hyde, 1906b, p. 739.

due partly to thc .<haking of sand like jelly and pnrily to sertling 2nd slidrng. In Sxn Francisco cnnsidernble tracts of "filled" land were shaken togcthcr and thud made tu settle a few feet,

and were at the same rune s l~dden lsicl sc\,cral fcct toward thc ha". Locating, by the street system, the ~ 6 i n i s a f surface movement*;" (he writer has demonstrated that every

subsldrn6e our moveme; a l 'n~,ruca~scd by the recent enrthqunke iseithcrjust along the edgeofor within an area whrch iormerly was swamp, salt marsh, mud flat or bay estuary in charncter. It i i interesting to see how ttle olattlnc ofthe rarthuuakr's footmarksof thls klnd in <,ur streetsuftodav outlinrs thc limitsofthe formcr .~~ ~ n~~ ~~~ ~~~ ~~~ .~~~~~ ~ ~~~ ~ ~~~~~~ ~~ ~~~~ ~~~~ ~ ~~~ ~~~~ - ~~~ ~ ~~ ~~~ , soli spots of the formations or) which San Francisco was b u ~ l t , and how the specially soft sputs are agaln revealed by the mcatcr movemrnt now ~ r ~ s e n t e d . ICont~nucd under lool;. 193. 206, and 216 in "Soecific

i r remiar settlement. The streets naturally followed the changes in elevation i n d a wave-likeeffect was ~ d u c c d . Observations on Market, M~ssio", East and other jtreZts frequently indlcnrr an -implitude ofwave lrlght of two f+rt, whlle i,ocnsionnl places are found with arsilter differerxes in elevation. In the Mission district. and in certain other uans of San Francrsro. as, for instance, alone the courses of formcr tidal streams, large areas of filled land exist. In such eades, t h e effect prddueed" by the earthquake was not generally in the form of waves, as already described, for the eastern portion of the city was hasin-like, representing local settlement in the streets and adjacent areas, and in some eases, decided misalignment. The most important wave-like distortions were observed on lower Market and Mission Sts., and on East St. along- the present water front.*** Where the ground was hilly and solid, i t was not decidedly affected by the eart5qualie shock


TABLE 4.--Eseerpted notes containing general descriptions of ground failure ond consequent pipeline breaks in Son Francisco-Continued

Jordan, 1907, p. 123.

Jordan, 1907, p. 98.

Preliminary Report, 1906, p. 15.

~ e s l k s Weekly, 1906e.

Chicago Record-Herald, 1906b.

Seattle Post-Intelligencer, 1906a.

Derleth, 1906a, p. 503.

Gilbert, Humphrey, Sewell, and SoulB, 1907, pl. 56.


Scbussler, 1906 p. 1.

Schussler, 1906, p. 33.

Gilbert, Humphrey, Sewell, and SoulB, 1907, p. 19.

Derleth, 1906a, p. 503.

Gilbert, Humphrey, Sewell, and SoulB, 1907, p. 56.

5. [Picture caption] "Toppling like houses of cards." [Picture caption1 SUNKEN FLATS SHOWING HUGE FISSURES MADE IN THE STREET*** Reproduced

from the Los Angeles Times. [Picture caption] FISSURE IN SAN FRANCISCO STREET CAUSED BY EARTHQUAKE: "Flat Building on

Left Sank One Story into the Ground." In many parts of the city, side hills resting upon original sand dunes have been bodily moved and deformed by

wave-like and sliding motions. Author's summary of pertinent data on map. Principal earthquake breaks in streets are marked a t the

following places on this map. Valencia Street between 18th and 19th: Seventeenth Street between Mission and Capp: Howard street between 17th and 18th: Shatwell Street between 17th and 18th: Seventeenth Street between Folsom and Harrison: Harrison Street between 17th and 18th: Fifteenth Street between Harrison and York: Fourteenth Street between Mission and Harrison: Eleventh Street between Harrison and Bryant: and the corner of Seventh Street and Mission Street. [See also lac. 2141

In San Francisco, all serious fractures of water mains, as a result of the earthquake, were due to lateral displacements, or subsidences of filled or soft ground across which, unfortunately, the main supply pipes passed. The displacement laterally amounted in places to as much as 6 or 7 ft.; vertically, i t amounted to several feet.

The most serious injury sustained by the [water] works were the ruptures caused by the earthquake, in hundreds of places, in our city main pipe distributing system, especially where the streets crossed filled ground and, particularly, where such filled ground covered former deep swamps, which swamps, during the earthquake, subsided, tearing off sewers as well as water and gas pipes.

The eity pipe distributing system was broken and in many instances torn and twisted off, especially in places where the ground, over which the streets had been constructed, had been poorly and loosely filled over old deep swamps and soft marshes. There were also a number ofbreaks in the streets that passed with deep loose fills over farmer ravines.

The failure to control the fire by reason of the crippling of the water supply was not due to the failure of the system outside of the eity, but to the breaks m the distributing mains within the city, whlch rendered unavailable about 80,000,000 gallons of water stored within the city limits. These breaks occurred (see the map, PI. LVI) wherever the pipes passed through soft or made ground. No breaks occurred where the cast-iron pipe was laid in solid ground or rock.

The damage by the earthquake which was the direct cause of the city's great lire loss, occurred in the water system. The main conduits entering the city were greatly damaged, and the pipes running through soft materials were very generally destroyed.

The importance of proper construction and distribution of the water mains in districts liable to earthquakes is demonstrated by the fact that the greatest damage in San Francisco, fully 85 per cent ofthe total, was by fire. The action of the earthquake in starting the fires which grew to a great conflagration seems insignificant compared to the breaking of the water mains, which left the city defenseless against the flames.


TABLE 4.-Excerpted notes containing general descriptions of ground failure and consequent piepline breaks in San Franeiseo-Continued

Note Reference

20 Gilbert, Humphrey, Sewell, and Souli., 1907, p. 66.

21 Duryea and others, 1907, p. 324.

22 San Francisco County, 1908, p. 732.

23 San Francisco Chronicle, 1906~.

24 Huber, 1930, p. 270.

25 Huber, 1930, p. 270.

26 Holden, 1898, p. 78.

27 Davidson, 1906, p. 180.

28 Wood, Allen, and Heck, 1939, p. 6.

Quotation

From what was left ofthe ruins themselves, and from the testimony of competent observers, including engineer officers who were ordered into the business district of San Francisco immediately after the earthquake and before the fire bad destroyed the evidences of earthquake damage, I think it is quite certain that the earthquake damage was extensive and severe. There were no available data on which to base an accurate estimate, but I formed a general impression that the damage done by the earthquake alone was a t least as great as 10 per cent ofthe total damage by fire and earthquake combined. The damage from the earthquake, however, was localized in a remarkable degree.

On the areas aver the old tide flats, the walls of the old 3-story and 4-story brick buildings were built on "rafts" made of layers of plank. These settled, and the space between them was arched up like the back of a turtle, sometimes as much as 6 R. between walls 30 R. apart.

The Board of Public Works realized that a vast amount of emergency work confronted them, and for which work the funds available were wholly inadequate to defray the cost. They determined that conditions forced upon them the immediate performance of the following work regardless of the moneys set aside to their department:***. 10. The survey monuments tbat had been shifted by the movement of streets must be reset before lot surveys for building reconstruction can be furnished.

The following sewers were found to be in bad condition, and upon which repairs were made: Fourteenth street between Valencia and Howard streets. loc 214 *** Eigbteenth street between Church and Valencia streets--\lo": 216\***: Mission street between Eighteenth and Nineteenth streets. [loc. 2161;'"*. Powell street between North Point and Beach streets;";'. Vallejo street adjacent to Van Ness avenue--175 feet of brick sewer and 125 feet of 18-inch pipe sewer

were reconstructed. [loc. 2211. Diamond street northerly from Chenery street-1,500 feer"* reconstructed. Seventh street between Falsom and Harrison streets[ loc. 212]***. Eighth street between Bryant and Brannan streets[ loc. 214]***. Crossing of Bryant and Fourth streets-[lac. 205]'**. Crossing of Seventeenth and Howard streetc[loc. 215]***. Hayes street between Broderick and Baker streets. Crossing of Seventeenth and Mission streets-[loe. 214]***. Crossing of Central avenue and Turk street.**' Valencia street between Eighteenth and Nineteenth s t ree t s130 feet of &foot sewer collapsed. [loc.

2161. Eleventh street between Harrison and Bryant streets-70 feet broken. Union street between Steiner and Pierce s treets[ loc. 222]***. Four gangs of sewer cleaners worked on Fourteenth street between Folsom and Howard streets [loc.

2141, and Valencia street between Eighteenth and Nineteenth streets. On Fourteenth street, between Valencia and Harrison streets; on Harrison street, between Twelfth and Thir-

teenth streets; on Eleventh street, between Harrison and Bryant streets; an Ninth street, between Bryant and Brannan streets; on Dore street, between Bryant and Brannan streets; on Laguna street, between Greenwich and Lombard streets; on Shatwell street, between Seventeenth and Eigbteenth streets; on Seven- teenth street, between Folsom and Harrison streets; on Howard street, between Seventeenth and Eighteenth streets.

[I868 earthquake] Then as to the destruction of property. Not a single strongly and honestly built house on the solid land of the city has been materially injured, while very few houses of any kind on the solid land have been injured a t all. The damage done was chiefly confined to the old and inferior structures, pretentious and imposing as some ofthem may have been, erected upon the flats formed by filling in about 200 acres of water lots along the northeast front of the city. This filling, awing to the deep substratum of mud, was essentially unsubstantial and unsafe, and even the iles driven through i t have proved, as in the case of the Custom House, not to be a sufficient foundation kr large brick or stone houses in a place liable to earthquakes.

Beginning with the issue of October 23, 1868, the San Francisco Bulletin publishes a detailed itemized list of estimated damage to buildings, the individual buildings being listed by blocks. ***the principal damage occurred on land reclaimed from San Francisco Bay and whieh is known to afford unsatisfactory foundation conditions.

1868, October 21, San Francisco. The shack was longer and more severe than tbat of October 8,1865. Several persons were killed by falling cornices. *** The surface ofthe earth visibly undulated. ***Hen. Horace Davis writes tbat the destruction in S. F. was greatest along the old beach-line of the city, beyond whieh the soil had been filled in.

I was one of the committee of investigation of the 1868 earthquake, and i t demonstrated that the course of greatest dislocation at the surface of the ground was on the line of contacl between the "made" land or the alluuial soil with the rocky stratum.

This is repeated in this 119061 earthquake***. 1865 October 8. *** IX a t least. At San Francisco the greatest damage was to the less strongly constructed

buildings on made land; structures on solid ground, or well constructed, suffered little damage; water mains and gas pipes brake in several places because of shifting ground, and a crevice opened in one street.

I Text continued on pace 60 /


FIGURE 18.-Hillside landslide in redwood forest about 4 mi (6.4 kml above Alma (loc. 55). The landslide has dammed Los Gatos Creek from the south. (Photograph by J. C. Branner, courtesy of Stanford University Archives.)

('san!qarv K?!sian!un plojus?~ JO Ksalrno~ 'uo!pa[loa 1auus.q '3 'p '!lag '8 Kq qdeGo?oqd) .:ysad K~zz!~ UOIJ aqaue[ene-qlie~ .su!sluno~ zna3 s?ua~ 'yaar3 laaaa, uo!ldea q?!~ (apZ1 '~d '9061) Slaq)o pm uasfie? u! paqsgqnd K[sno!hald qdelZoloqd .($L ,901)

aj!1 auo Zu!yel pus [[!w a[Zu!qs ueull~o~ aqlBu!Ko~lsap meaqsufiop (my 8'0) !m 9.0 lnoqe paauenpe leq? ap![spue[ yaw3 .raaa-'61 mno~j


. . . .. . .~ - . -. - - .. . .. . . . .. .

FIGURE 20.-Flow failure in hills southeast of HalfMoon Bay (loe. 110). Note that the displaced sediments piled up in a ridge on the gently sloping terrain rather than spreading out. Similar photograph previously published in Lawson and others (1908, pl. 132A) with caption "Earth-flow in hills east of Half Moon Bay." (J. C. Branner collection, courtesy of Stanford University Archives.)


FIGURE 21.-Flow failure east of HalfMoan Bay lloc. l l l l . A . Cavity with 10-ft (3-m)-high walls from which sediments flowed. Note the man (circle) standing a t left edge of cavity. Photograph previously published in Lawson and others (1908, pl. 132B) with caption "Earth-flow in small valley near Half Moon Bay."B. Panoramic continuation ofA showing ridge of deposited debris. Note the pick leaning against debris in center of picture and man standing on rim of cavity behind debris at right. (Photograph by R. A. Anderson, J. C. Branner collection, courtesy of Stanford University Archives.)


F l c u n ~ 22.-Flow failure down a hillside slope on the Nunez Ranch 4 mi (6.4 km) east of Half Moon Bay (loc. 114). Note the man (lower circle) standing at the base of the deposited debris and a second man (upper circle) standing on the lower edge of the cavity at the top of the slide. Additional incipient flow failures, with much smaller movements, also occurred on the convex hill to the left of the principal landslide. Photograph previously published in Lawson and others (1908, pl. 133B1 with caption "Earth-flow 4 miles east of Half Moon Bay." (Photograph by R. A. Anderson, J. C. Branner collection, courtesy of Stanford Univeristy Archives.)

HISTORIC GROUND FAILURES IN NORTHERN CALIFORNIA TRIGGERED BY EARTHQUAKES

FIGURE 23.-Rockfalls along coastal bluffs between Ocean Avenue, San Francisco, and Mussel Rock (loc. 132). (Photograph by H. 0. Wood, courtesy of The Bancroft Library, University of California, Berkeley.)

FIGURE 24.-Landslide on steep hillside near Mussel Rock (loc. 1321. These and similar landslides destroyed several miles of highway and railroad grades during the 1906 earthquake. IJ. C. Branner collection, courtesy of Stanford University Archives.)


FIGURE 25.-Cavity of flow failure on the south side of San Bruno

Mountain above Mt. Olivet Cemetery near Colma (lot. 135). (Pho- F~~~~~ 2 6 . - ~ ~ i l ~ ,,f electric railway on marsh west sari B~~~~ tograph by A. C. Lawson, courtesy of The Bancroft Library, Uni- that were buckled by during 1g,,6 earthquake (lot, versity of California, Berkeley.) 141). Buckling was mast likely a consequence of lateral spreading.

Photograph previously published in Lawson and others (1908, pl. 97C) with caption "Roadbed and rails of electric railway an marsh west of San Bruno." (Photograph by R. B. M., Branner Collection, courtesy of Stanford University Archives.)

FIGURE 27.-Ground cracks in the vicinity of Coyote Creek west of Milpitas (lac. 149). A. Cracks caused by slumping and lateral spreading near the creek channe1.B. Cracks in road several hundred feet west of Coyote Creek. (Photographs h m J. C. Branner Collection, courtesy of Stanford University Archives.)


FIGURF 28.-Sand boils in field between Milpitas and Coyote Creek (lac. 1491. Note bridge over Coyote Creek in center background. Photograph by J. C. Branner, previously published in Lawson and others (1908, pl. 143A) with caption "Craterlets in fields near Milpitas." (Courtesy of The Bancroft Library, University of California, Berkeley.)

West E o ~ t 30 Amvroximall 1905 ground fsilure zone

FIGURE 29.-Geotechnical section across Coyote Creek a t the Alviso-Milpitas road (State Highway 237) bridge, viewed north (loc. 149). A wooden bridge a t this site was compressed about 3 ft (0.9 ml by spreading afthe banks into the creek in 1906. The banks a t this site were also "shaken together" during the 1868 earthquake (data from Division of Highways, 1967).


FIGURE 30.-Aerial photograph of commercial and shipping district of San Francisco showing locations of lateral-spreading and ground settlement failures that disrupted the city during the 1906 earthquake. Liquefaction within subsurface saturated granular layers is the evident cause of the failures.

FIOURE 31.-Cracks and separations in roadway pavement near the . . San Francisco \r,nteriront caused by lareral ~preading in lhc foot of Market zone ,lot. 1033 Photograph previously published hy Givens ,1906) with caDrlon "break and two-foot 10.6 rnl sink in Enst Srrect near Ferry Building" and by Schussler (1906, p. 91) with caption "street on water front badly broken up."


t 1906 ground failure zone

EXPLANATION

Bm Artificial fill Bay mud and clay

Predominonrly ddue sond but includessilr, clay, Plastic gray silty clay: some lenses of sand, rock woste, rnanmode debris, and organic waste pear, and slreil fmgmenrs, fluid to soft

upper loyers: moderately stiff cloy or deptlt

- - - - - - - Approximate water table

Penetration resistance-blow/ft 275 lb weight dropping 18 in. on type U Dames and Moore sampler

FIGURE 32.-Geotechnical section beneath Market Street in the foot of Market zone


0 100 200 300 400 FEET I I I I

I I 0 50 100 150 200 METERS

piLJ Dune sand Quaternary depasits,.undifferentiated

Cleo,l wei1:sorted fine to medium sand; yeiiowislt Locoiiy ineil;des Colmo Formotior~;oneonsolid~?ted, fine browrr to ligl~tgroy.Mnxi,nem t1,ickness appro*. to meditm? sond and, in piaces,cloy beds. 6 irz.to 5 fr. imotqly I50 feet thick

Water table in borings at time of drilling (March-lul,y 1964)

Location of borings from which cross section is constructed

(loe. 193) (data from Dames and Moore, Inc., 1964; geology infe&ed fmm Schlocker, 1974).


FIOURE 33.-Disruption of block pavement and sidewalk on Columbia Street just south of Folsom Street (lac. 205). Photograph previously published in Lawson and others (1908, pl. 89A) with caption "Columbia Street, just south of Falsom Street, San Francisco. Slumping, depression, and furrowing of block pavement." (Photograph by H. 0. Wood, courtesy of The Baacroft Library, University of California, Berkeley.)


FLGUEE 34.-Rails on Fifth Street near Harrison Street, San Francisco, pulled apart by extensional movements associated with lateral spreading of underlying sediments (loc. 205). (Photograph by G. K. Gilbert.)


FIGURE 35.-Damage to San Francisco Post Office, Seventh and Mission Streets, caused by ground failure (loc. 210).A. View of southeast entrance showing differential, vertical movement of lower, nonstructural facing around building. B. View northeastward in front of building showing differential, vertical, and lateral movement of sidewalk. (Photographs courtesy of H. J. Degenkalb and Associates, San Francisco). C. View northeastward in front of Post Office showing settlement around building and lateral displacement of sidewalk to the southeast. (Photograph courtesy of San Francisco Public Library.)


J + 2000 4000 BOD0 FEET

I I I I

I

B 500 ,000 ,SO0 2000METERE

20 , B'

FIGURE 36.-Geotechnical profile across south of Market zone at the James Lick Skyway between Third and Sixth Streets, San Francisco (loc. 205). (Data from Division of Highways, 1952; geology inferred from Sehlocker, 1974.)


Approximate location and direction from which picture was taken

FIGURE 31.-Schematic diagram of area between Ninth and Tenth Streets and Bryant and Brannan Streets in lower part of Mission Creek zone, San Francisco (loc. 214), showing approximate locations and directions from which photographs in figures 3 E 4 1 were taken.


FIGURE 38.-View along Dore Street from Bryant Street toward Brannan Street, San Francisco (lac. 214). A. Photograph aRer the 1906 earthquake showing undulations as large as 6 ft (1.8 m) in street. As much as 6 ft (1.8 rn) of lateral movement also occurred a t this location. Similar photograph previously published in Lawson and others (1908, pl. 89D) with caption "Looking along Dore Street, from Bryant toward Brannan. Undulating and fractured condition of pavement due to earthquake. Houses thrown offtheir underpinning and pitched out of the vertical." (Photograph from J. C. Branner collection, courtesy of Stanford University Archives). B. Dore Street today (September 1974) from approximately the same location as fig. 38A, showing ramps of the James Lick and Central Freeways and other structures constructed since 1906. C. Building a t corner of Bryant and Dore Streets damaged by differential vertical and lateral movements. (Photograph by H. 0 . Wood, courtesy of The Bancroft Library, University of California, Berkeley.)



FIGURE 39.Scarps and right-lateral displacements caused by lateral spreading a t two paints on Bryant Street near the intersection of Ninth Street (loc. 214). A. Between Ninth and Tenth Streets (?I. B. Between Eighth and Ninth Streets. (Photographs by G. K. Gilbert.)


FIGURE 40.-Views along Ninth Street between Bryant and Brannan Streets (loc. 214). A. View nodhwestward from near Brannan Street showing lateral displacement ofatreet, rails, curb, walk, and buildings. Photograph previously published by Gilbert and others (1907, u1.5) with caution "Results of earth flow. Ninth Street. San Francisco." and in Lawson and others (1908.~1. SIB) with c a ~ t i o n "Ninth Street, between Bryant and Brannan. Wcstward lurching of land toward tbrmcr creek channel where Doru Street now is" rl'l!orok~aph by G. K. Gilbert. X View northweatward showing building damage, some ofwhich is duc to sauthwestward lateral displacement ofthe


ground. (Photograph courtesy of San Francisco Public Library.) C. Clase-uo view of damage in midsection ofblock. (Photoera~h ceourtesv - .. . of Charles A. Smallwood., D. Close-up ~,Idamagr 31 north\r.ert end of hlock. Photograph previously ~ u b l s h e d in La\rsun nnd others (1908, pl. 91111 \tllh captlun "N~nth Srl-eel, between Brynnt and l3ronnan. Undulurrdn and i:;iur~nr! of t~nvemc.nt 2nd sidewalks Houscs over trough have been dropt from their underpinning." (Photograph by G. K. Gilbert.)


1811' S T R E E T b35

FIGURE 41.-View northeastward on Brannan Street, comer of Ninth Street (lac. 214). The scarp and settlement in the foreground marks the southern boundary of the ground failure on Ninth Street. (Photograph by G. K. Gilbert.)

FIGURE 42.-Schematic diagram of area between 17th and 18th Streets and Capp Street and South Van Ness Avenue in the central part of Mission Creek zone, San Francisco, showing locations and directions from which photographs in figures 43-47 were taken (loc. 215).


FIGURE 43.-Buckling of rails by compression on Howard Street (South Van Ness Avenue) near 17th Street (loc. 215). Photograph previously published in Gilbert and others (1907, pl. 6B) with caption "Buckling caused by earth flow, Howard Street, San Fran- cisco." and in Lawsan and others (1908, pl. 92B) with caption "Looking south on Howard Street from near Seventeenth Street. Compressional flexure of car rails." (Photograph by G. K. Gilbert.)

FIGURE 44.-Looking north an Howard Street (South Van Ness Av- enue) from near 18th Street toward l l thstreet , San Francisco (loc. 215). Rails offset laterally by lateral-spreading ground failure. (J. C. Branner Collection, courtesy of Stanford University Archives.)


FIGURE 4 5 . S c a r p s showing vertical movement and northward lateral movement (10". 215). View eastward an 18th Street. Intersection of Howard Street (South Van Ness Avenue) is in the middleground. lcourtesy of San Francisco Public Library.)


Floum 46.-Scarps, lateral and vertical displacements in Capp Street between 17th and 18th Streets (loc. 215). Photograph previously published by Zeigler (1906) with caption "Capp Street, near Seventeenth, damaged by earthquake" and in Schussler (1906, p. 95) with caption "Capp Street sunken."

"', . . .

FIGURE 47.-Buckled curbstone on Capp Street near 18th Street (lac. 215). Buckling was caused by sed~rnents shifting toward old channel of

I Mission Creek. (Photograph by G. K. Gilbert.)


FIGURE 48.-Valencia Street between 17th and 18th Streets lloc. 216). A. View northward shortly after earthquake showing collapsed Valcnrra Street Hotel in whlrh tens of people were kllled. S ~ t e 1;trer;tl d ~ ~ p l ; ~ c e m m r ufsrroct in front ~f hotel. ~ P h u t ~ g r a p h COIII.ICSY 01 tjcrkuy I'hotoScrv~cc, pre\~loualg Bear Photo B Vle\r suuthwsrd slier fire .chowlnc lxtaral ;and verrlcjl dlipl;~remmt*of6 it t1.h m and two temporarily repaired arterial water pipelines that were ruptured by the ground movements, cutting off the water supply to a major part of the city. (Photograph by Maran, courtesy of The Bancroft Library, University of California, Berkeley.)


FIGURE 49.-San Francisco in flames after 1906 shock. Fire fighting efforts were hampered by the unavailability of water, a consequence of the many major pipeline breaks that were caused by ground failures. (Photograph from P. E. Hotz collection, U.S. Geological Survey.)

FIGURE 50.-Lateral spread a t the Youth's Directory on 19th and Guerrero Streets (loe. 211). Photograph previously published in Lawson and others (1908, pl. 94A) with caption "View along Nineteenth Street, from Guerrero Street. Both ground and buildings moved north about 6 feet [1.2 m] toward center of old marsh, with component of movement down the channel." (Photograph by A. C. Lawson, courtesy of The Bancroft Library, University of California, Berkeley.)


0 600 FEET

50 100 150 ZOOMETERS

FIGURE 51.-Geotechnical section across Mission Creek zone at Mission Street between 15th and 20th


E 3 0 Radiolarian chert and shale Standard penetration-blowslft

Alternate beds of lrard bn'ttie chert, 1-5 in. thick, and brittle, crumbly shale. 118 to %it,. thick.

Locally includes bodies of massive chert a

Water table in borings at time of drilling (January-February 1964)

Dry unit weight-lb/ft3 cT3

Approximate water table

- Location of borings from which cross

section is constructed

Streets (loc. 216). (Data from Harding Associates, 1964; geology inferred from Schlocker, 1974.)


.-A, , .

FIGURE 52.-Disruption of Van Ness Avenue over a filled in ravine (lac. 221). Lateral movements as great as 3 ft (0.9 m) and vertical movements as great as 2 ft (0.6 m) occurred a t this location. Photo- graph previously published by Zeigler (1906) with caption "Break

- - .I in asphalt paving on Van Ness Avenue near Vallejo Street."

FIGURE 53.-Slump in Union Street between Pierce and Steiner Streets (loc. 2221. Photograph previously published in Lawson and others (1908, pl. 88B) with caption "Slip of a fill on Union Street, just west of Steiner Street, San Francisco." (Photograph by H. 0 . Wood, courtesy of The Baneroft Library, University of California, Berkeley.)


FIGURE 54.-Flow failure along shoreline of Lake Merced triggered by the 1957 Daly City earthquake (lot. 236). Photograph previously published in Bonilla (1960, p. 22) with caption "Damage to roadway by landslides along south arm af Lake Merced. View looking northwest." (Photograph by M. G. Bonilla.1

I Text continued on page 66 1

CALIFORNIA TRIGGERED BY EARTHQUAKES

Some of the largest lowland ground failures in 1906, both in areal extent and amount of movement, were generated beneath and marginal to Tomales Bay (locs. 255,259,266,267,269, 271,278,280). Settlements as large as 8 ft (2.4 m) were common beneath roadway fills (locs. 269, 279). Lateral displacements as large as 30 ft (9.1 m) or more caused considerable damage. For example lateral spreading toward the Lagunitas Creek channel (loc. 266) shortened a bridge by 6 ft (1.8 m), buckling the structure at its north end. A large failure occurred beneath Tomales Bay near Inverness (loc. 271, figs. 61-63) where westward lateral displacements as great as 25 f t (7.6 m) occurred beneath two boat piers 800 ft (240 m) apart. Gilbert (in Gilbert and others 1907, p. 8; and in Lawson and others, 1908, p. 79 (quoted under loc. 271, table 8)) concluded that these movements were caused by shifting of bay bottom sediments westward, upslope, a t least 30 ft (9 m) as a consequence of earthquake vibrations. It seems un- likely to us that unconsolidated sediments at this locality would slide uphill during an earthquake. Hence, we offer an alternate possible explanation that the movements may have been caused by a combination of lateral spreading of shoreline sediments into the bay and down-channel movement of bay bottom sediments. This down-channel movement is consistent with that observed in other areas during the earthquake and is conformable with gravity rather than in opposition to it.

Other areas where significant 1906 lowland ground failures occurred include the margins of Suisun Bay, where lateral movements of a few inches (loc. 252) and vertical movements of several feet (loc. 254) were found, and the west edge of the Cotati Valley near Sebastopol (loc. 293), where rows of trees in an orchard were shifted several feet laterally.

Santa Rosa (loc. 295) sustained more damage than surrounding areas during earthquakes in 1868 (Law- son and others, 1908, p. 439), 1906 (Lawson and others, 1908, p. 19%203), and 1969 (Huffman and Youd, in Cloud and others, 1970). There is no evidence that ground failures were a factor in producing the greater damage in any of these events. 111 fact, several specific notes show an absence of ground failure in the main part of Santa Rosa in 1906 (Derleth, in Jordan 1907, p. 188 (loc. 295)) and in 1969 (Huffman and Youd, in Cloud and others, 1970, p. 54 (loc. 295)). Hence, earthquake damage in Santa Rosa has been a consequence of ground shaking, rather than ground failure.

60 HISTORIC GROUND FAILURES IN NORTHERN

NORTH BAY COUNTIES REGION

The north bay counties region includes Marin, Napa, Solano, Sonoma, and Yolo Counties, northern Contra Costa County, and the southern parts of Mendocino and Lake Counties (pl. 2 and table 6, locs. 183-192; pl. 4 and table 8, locs. 24g311; figs. 55-66). Several mountain ranges and intermontane valleys, a long segment of the Pacific Coast, and the northern segment of San Francisco, San Pablo, and Suisun Bays are in this region. The epicenter of the 1906 San Francisco earthquake (near Olema, Marin County) and several segments of San Andreas fault rupture between Bolinas Lagoon and Point Arena are also included.

Only four events have been documented in addition to the 1906 shock that have triggered even as much as very slight ground failures in the north bay counties region. These shocks include an event near Mare Is- land (loc. 251) in 1898, a swarm of shocks along the west edge of the Sacramento Valley (locs. 255-259) in 1892, and the 1969 Santa Rosa earthquakes (loc. 295). Hence, the 1906 event is by far the most important event for earthquake-related ground failure studies in this region.

I Hillside landslides have been the most common form 1 of seismically triggered ground failures reported in the \ north bay counties region. Furthermore, it is likely i that only a fraction of the 1906 occurrences of these

failures were documented. One of the landforms most

I vulnerable to seismically generated landslides is the coastal bluffs. In 1906 extensive landslides, mostly ZZ-fallS,Were observed along the bluffs near Bolinas Lagoon (loc. 188) and between Bodega Head and Point Arena (loc. 300). Flows also occurred at at least two locations both near Tomales Bay (loc. 274, fig. 64). A large landslide north of Santa Rosa, the Maacama landslide (loc. 2981, is noteworthy because (1) it involved considerable displacement of a large mass of rock that in turn dammed up a creek, (2) it is particularly well described, and (3) it is readily relocatable in the field today.

Differential settlement, lateral spreads, and ground cracks were common failure types in lowland alluvial areas. In many instances, sand boils were associated with these failures, indicating that liquefaction was a factor in their formation. For example, the flood plain of the Russian River inland for 25 miles (40 km) from the Pacific Ocean (loc. 299) was severely disturbed by these types of lowland failures.


FIGURE 56.-Cracks along the edge ofa sag pond near Bolinas (loc. 1871. Photograph previously published in Gilbert and others (1907, pl. 4B) with caption "Secondary cracks, with settling, Bolinas" and in Lawson and others (1908, pl. 52B) with the caption "Earthquake cracks in Bolinas a t edge of an earthquake sag." (Photograph by G. K. Gilbert.)


FIGURE 57.-Buildings tipped into the water a t the Bolinas waterfront (lac. 189). (Photograph by G. K. Gilbert.)

FIGURE 58.-Cracks and settlement a t the head of a lateral spread between Olema and Inverness (loc. 266). (Photograph by G. K. Gilbert.)

FIGURE 59.-Cracks generated by lateral spreading southwest of FIGURE 60.-Cracking and subsidence of road grade across a marsh Point Reyes Station (lac. 266). Photograph previously published in southwest of Paint Reyes Station (loc. 267). Photograph previously Lawson and others (1908, pl. 50B) with caption "Faults in road published in Lawson and others (1908, DI. 50A) with c a ~ t i a n "Road embankment, juuthwrst oft'ninr Reyes Station. Fault-truce is be- embankment broken by shaklngofs~~tt ground beneath. 4,uthivest yond fence.. Ground lurched roward marsh of B e i ~ r Valley C~.eek." uiPo~nt Heves Station and 10 rods 150 rnl from fault-trace." photo-

(Photograph by G. K. Gilbert.) graph by G. K. Gilbert.)


FIGURE 61.-Ridged bottom of Tomales Bay after 1906 earthquake (loc. 270). Similar to photograph previously published in Gilbert and others (1907, pl. 8A) with caption "Earthquake ridges an tidal flat, Tomales Bay" and in Lawson and others (1908, pl. 54B) with caption "Ridged mud plain 1 mile 11.6 kml from Inverness. Looking east-southeast. Mr. Hamilton's barn a t right. April 28, 1906. Tide is low. Pools occupy the deeper troughs." (Photograph by G. K. Gilbert.)

FIGURE 62.Shifted sediments of Tomales Bay (loc. 270). Photograph previously published in Gilbert and others (1907, pl. 7A) with caption "Shifted bottom of Tamales Bay" and in Lawson and others (1908, pl. 55B) with caption "South part of Inverness shoal, a t low tide, April 28, 1906. Looking north-northwest. Lane of water separates firm, gravelly beach from mud shifted shoreward by earthquake." (Photograph by G. K. Gilbert.)


FIGURE 63.-Boat piers a t Inverness displaced during earthquake Photograph previously published in Lawson and others (1908, pl. (loc. 271). A. Martinelli's pier. Photograph previously published in 57B) with caption "Bailey's pier a t Inverness. Originally straight; Lawson and others (1908, pl. 57A) with caption "Martinelli's pier shifted and much broken by earthquake. In subsequent repairs a t Inverness. Originally straight; shifted and broken by earth- curvature caused by earthquake was retained." (Photographs by quake. Repaired before photograph was taken." B. Bailey's pier. G. K. Gilbert.)

FIGURE 64.-Hillside flow failure 2 mi (3.2 km) west of Inverness and 1 hi (1.6 km) south of Sunshine Ranch (lac. 214). A hillside bog was set in motion by the shack and flowed dawn the slope as a stream of mud. (Photograph by G. K. Gilbert.)


FIGURE 65.-Hillside landslide in roadeut (loc. 276). Photagraph previously published in Lawson and others (1908, pl. 53B) with caption "Landslide from road-cliff about two miles [3.2 km] west of Inverness. Slide occurred a t time of earthquake." (Photograph by G. K. Gilbert.)

FIGURE 66.-Landslide on the Hutton Ranch, east side of Garcia River Valley (loc. 307). Toe oflandslide with transported trees is at left. Toe of slide also caused "wrinkling" of barley field in foreground. (Photograph by F. E. Matthes, courtesy ofThe Bancroft Library, University of California, Berkeley.)

F I ~ U R E 67.-Cape Fortunas (False Cape) landslide, one of the largest landslides triggered by the 1906 shock (loc. 339). A. View toward by Lawson and others (1908, pls. 127A, B) with caption "Earth-slump at Cape Fartunas, Humboldt County."


NORTH COAST COUNTIES REGION

Included in the north coast region are all of Hum- boldt County and northern Mendocin0 County (PI. 5 and table 9, lots. 312354; fig. 67). w hi^ region is generally mountainous with narrow intermontane valleys. The San Andreas fault trends offshore near Point Arena at the south margin of the region. ~h~ 1906 rupture on that fault extended as far north as Point Arena and probably continued for some distance northwestward off the Mendocino Coast. Surface ruptures as a result of tectonic faulting occurred at Shelter Cove in 1906 (Oakeshott, in Bailey, 1966, p. 361), indicating that seismic energy was released at least that far north along the coast.

Major landslides were noted along the coastal bluffs from Point Arena to Cape Mendocino (locs. 312, 332, 337). These slides were generally of the rockfall type and were most notable on the higher bluffs between Point Delgada and Cape Mendocino (loc. 332).

A large landslide called the Cape Fortunas landslide occurred in the coastal hills just north of False Cape, which is located about 30 mi (50 km) southeast of Eureka (loc. 339, fig. 67). The reports (Lawson and

others, 1908, p. 390) indicate that this slide, which was about 1 mi (1.6 km) in length and 0.250.5 mi (0.40.8 km) wide, moved as much as 1,300 ft (400 m) horizon- tally into the ocean. However, the total difference in elevation between head and toe of the landslide was only about 500 ft (150 m); hence the lateral component of movement was several times larger than the vertical component. The Cape Fortunas landslide thus may have had some similarities with lateral spreads that developed in the Anchorage, Alaska, area during the 1964 Alaska earthquake (for example, the Turns- gain Heights landslide Wansen, 1966, P. A5SA66; Seed, 1968)).

Very few hillside landslides were reported in 1906 at inland locations in the north coast area. This may have been a consequence of distance from the source of seismic energy release, sparse investigative coverage, or local geologic conditions. Locally, landslides were reported in areas such as Petrolia (loc. 338) both in 1906 and during earthquakes in 1923 and 1968. Moderate- sized landslides were also reported locally in the Eureka and Arcata areas during events in 1927 and 1954 (locs. 353, 354).

scarp. B . View toward toe showing extension of toe into Pacific Ocean in background. Similar phatagraphs previously published (Photographs by A. S. Eakle, courtesy of The Bancratt Library, University of California, Berkeley.)

SUMMARY AND CONCLUSIONS 67

During the 1906 shock, considerable lateral spreading, differential settlement, and ground cracking developed in flood plain sediments near the mouth of the ha1 River (locs. 340, 344). These failures, which were similar to ground failures generated along other major rivers in northern California, were accompanied by the pervasive eruption of sand boils, indicating that liquefaction was a factor in their development. Differ- ential vertical displacements as large as 3 ft (0.9 m) were common in the Ferndale area where the effects were particularly severe. No measurements of differential lateral movements were given, but the abun- dance of open fissures indicate that significant lateral displacements must have also occurred. During the 1954 earthquake, settlements as large as 0.5 ft (150 mm) occurred in the older part of Eureka, which is constructed on fill. Several waterlines were broken in that area, presumably as a result of ground displacements.

SUMMARY AND CONCLUSIONS

Historically, major ground failures triggered by earthquakes in northern California have been limited to the Coast Range province; however, minor failures have occurred at numerous localities throughout the region. The historical record shows that except for offshore shocks, the size of the geographic area affected and the number and the general severity of ground failures increase markedly with Richter magnitude. . --- .._ - Hence, the largest historical event, the 1906 San Fran- cisco earthquake, has been the most important generator of ground failures. That shock triggered failures over a 370-mi (600-km)-long zone extending from southern Monterey County on the south to Eureka on the north and inland as far as 60 mi (100 km) from the Pacific Coast.

Geologic, hydrologic, and topographic setting has great influence on ground failure development. Areas s 1 Y


I especially vulnerable to ground failure have been over- ' steepened slopes, such as streambanks and coastal bluffs, and lowland deposits, principally Holocene flood ' plain deposits, deltaic deposits, and poorly compacted

j fills, where liquefaction has been the major cause of I eround instabilitv.

i ' Hillside - landslides triggered by the 1906 earthquake were too numerous for the postearthquake investigators to document each occurrence. Most of the land-

of ground failures are probable at these locations dur- . . "^ .~ -_,--.-.---- i~g.Lvfiure~strong-ea~thgu?kes.

Because of recent population growth and land development, the potential for landslide and other ground failure damage during a large earthquake is enormous now compared to that in 1906.

REFERENCES CITED

Anderson, Robert, 1907, Earth-flows a t the time ofthe San Francisco

slides occurred in the Coast Ranges within a few mi1.e~ earthquake bbs.1: Geol. Sot. America Bull., v. 18, P. 643. Alameda Daily Argus, 1906, in Alameda: Alameda, Calif., April of~~~t.~_wld>~t. Because there was llttle de- , , , ,,,

. . / \ merit of many ground failures includiag.fl~~?..s,..lateral / Branson, W., 1959, The earth shook, the s k i burned: ~ e w k a r k ,

velO~ment in the mountainous and because most of the landslides were small or involved little displacement, damage from hillside landslides was small compared to other damage sources. Nevertheless, where hillside landslides impinged on the works of man, the were generally disastrous' For example, 10 men were killed and 2 lumber mills destroyed by landslides in the Santa Cruz mountains, and 3 mi (4.8 km) of the Ocean Shore Railroad was practically obliterated by landslides along the coastal bluffs south of Sari Francisco.

\ Liquefaction was a primary factor in the develop-

-", The Argonaut, 1906, Photograph: San Francisco, Calif., April 28,

1906, ". 58, no. 1520, p. 2. Bailey, E. H., ed., 1966, Geology of northern California: California

Div. Mines and Geol. lgO, 507 p. Bancroft, H. H., 1882, History of California: San Francisco, A. L.

Bancroft and Co., v. 6, p. 200. Blue Lake Advocate, 1954, Earthquake hits county-loss heavy:

Blue Lake California, v. 66, Dec. 23, 1954, p. I. Bonilla, M. G., 1959, Geologic observations in the epicentral area of

the San Francisco earthquake of March 22, 1957, in San Fran- cisco Earthquake of March 1957: California Div. Mines and Geology Spec, Rept, no, 57, p, 2k37,

-1960, Landslides in the San Francisco South quadrangle, California: U.S. Geol. Survey o~en-file r e~o r t , 44'0. 10 figs.

. .~ ~ ... .~ . . ~ ~ v f : forms most vulnerable to this type of failure. Bridges, breaks along the San Andreas fault between point Delgada and

.i roadways, pipelines, and buildings suffered consider- Bolinas Bay, California: U.S. Geol. Survey Misc. Geol. Inv. Map

;! - :*- -~ \ spreads, slumping of streambanks,~anhground_sett~~~

-_.. -.. __ I . .~~ ..., ~ ~ . - . , . _. -- l____ md spreads were the most and most damaging . ... . . .. ... liquefaction-induced ground failure. : Fl-o.6xi;iain and loose~sax.fiil..ae~PPossitts ;;eereet-Leeel-a-n-;l

~ ~ A

Doubleday & Ca., lg2 P. Brown, A. A,, and others, 1932, Subsidence and the foundation prob-

lem in San Francisco; a report of the subsoil committee: Am. Soc. civil Engineers, Sari Francisco 1932, p, 29,

rown, R. D. and Wolfe, E. W., 1972, Map showing recently active

beneath -_.- five lateral-spreadingsi~~FIOEsss~eT~~~d _-- on several sandy hilKides but did little damage be-

sparse development in the affected areas. Several instances have been reported of the same

' able lateral-spreading damage. Pipeline breaks were : , ' ' particularly critical in San Francisco, cutting off the

water supply to a city that was soon afterward in flames. Recent borehole data show loose saturated sand

a portion of the Eel River and selected tributaries: California Dept. Water Resources, Northern Dist. Middle Fork Eel River Devel., Memo. Rept., Sept. 1971.

Carey, E. P., 1906, The great fault of California and the San Fran- cisco earthquake, April 18, 1906: Jour. Geography, v. 5, no. 7,

The Bulletin, 1906, Earth cracks small river: San Francisco, Califor- nia, April 20, 1906, p, 3.

California Department of Water Resources, 1971, Reconnaissance studv of landslide conditions and related sediment ~roduction on

type of failure occurring re~eatedlv at the same loca- - I... :.--~.

slides similar in nature and location occurred during -... -..-a

both the 1906 San Francisco earthquake and the 1957 Daly City earthquake on steep slopes near Daly City

I P. 28%301 - - tion in more than one earthauake,For examDle, land-

stricken: Chicago, Ill., April 19, 1906, v. 6, no. 248, p. 3. The Chicago Record-Herald, 1906a, Flee to the parks to escape

flames: Chicago, Ill., April 23, 1906, v. 25, no. 299, p. 5. -1906b. Sunken flats showing huge fissures made in the street:

I ~ h i & g o Evening American, 1906, J. R. Rainey visits cities also

- (lots. 23Z242). Ground cracks -and slumping of . . . . _ ,;> =___- - .-..- ~, ~. streamb~~nks,.occurred along Coyote Creek between San Jose and San Francisco Bay (loc. 149) during both the 1868 and 1906 events. Lateral-spreading failures of ..: --._ -.< -_.. %_. . _.- the types that developed in San Francisco during the 1906 shock (locs. 193-217), but with smaller displacements, also developed during shocks in 1868 (locs. 19S202, 205,209) and 1865 (locs. 202, 209,212). This

i I r . evidence indicates that if geologic, hydrologic, and top- , . .. . . . ~ ~ . ..... -. .

' I ~graphic conditions remain unchanged, similar types d / _I_"..._.._._,_-- - . - :_______~r~~a.~

(locs. 132,133) and around the margins of Lake Merced Cloud, W. K., and others, 1970, the Santa Rosa earthquakes of Oc-

tober 1969: California Div. Mines and Geology, Mineral Inf. Service, v. 23, no. 3, p. 42-63.

Coffman, J.L., and von Hake, C. A., 1973, Earthquake history of the United States (rev. ed.): U.S. Environmental Data Service,

Pub. 41-1,208 p. Dames and Moore, Inc., 1964, Soil investigation and analyses Em-

barcadero regional station and cross-over structure, Bay Area Rapid Transit District, San Francisco, California: Unpub. rept., Dames and Moore, Inc., contract S-702,21 p., numerous plates.

Davidson, George, 1906, The San Francisco earthquake of 1906: Am. Philos. Soc. Proc., v. 45, no. 183, p. 164182.

I Chicago, Ill., April 25,1906, ;. 2< no. 301, p. 2.

REFERENCES

Davison, C., 1906, The San Francisco earthquake of April 18: Scien- tific American Supp. no. 1586, p. 25416, May 26, 1906.

Derleth, Charles, Jr., 1906a, Report by Prof. C. Derleth, Jr.: En- gineering News, v. 55, no. 18, p. 503-504.

----1906b, Some effects of the San Francisco earthquake on water-works, streets, sewers, car tracks and buildings: En- gineering News, v. 55, no. 20, p. 545554.

-1906c, Additional examples of street subsidence in San Fran- cisco: Engineering News, v. 55, no. 21, p. 58S581.

-1906d, The destructive extent of the San Francisco earthquake: Engineering News, v. 55, no. 26, p. 707-713.

Division of Highways, 1952, Bayshore freeway, 8th Street to 3rd Street foundation investigation: Unpuh. rept., California Dept. Public Works,BridgeDept., bridgeno. 3 4 4 3 IVL,fileno.T-7-H, drawing no. PR-18561.

-1964, Route 68, bridge acrosssalinas River, log oftest borings: Unpub. rept., California Dept. Public Works, contract no. 1 6 020814, document no. S0001070.

-1967, Boring logs a t bridge no. 37-84 on State Highway 237, Mt. View-Alviso Road, a t Coyote Creek: Unpub. rept., California Dept. Public Works.

Duryea, E., Jr. and others, 1907, The effects of the San Francisco earthquake ofApril 18, 1906, on engineering constructions: Am. Soc. Civil Engineers Trans., v. 59, paper no. 1056, p. 205329.

Earthquake Engineering Research Institute Newsletter, 1975, Let- ter by H. H. Howard: Earthquake Engineering Research Inst. Newsletter v. 9, no. 1, p. 103.

Engineering News, 1906, TheSan Francisco disaster, 1906; Earth- quake and fire ruin in the bay counties, California: Eng. News, v. 55, no. 17, p. 475480.

Environmental Data Service, 1971, California, Annual summary, Climatological data, total precipitation and departures from normal: U.S. Dept. Commerce, Natl. Oceanog. and Atmospheric Adm., v. 75, no. 13, table 2, p. 475481.

The Evening Bee, 1906a, Sacramento suffers no real damage from the effect of the shock: Sacramento, Calif., April 18, 1906, v. 99, no. 16, 358, p. 1.

-1906b. Trains operating over marshes: Sacramento, Calif., April 19, 1906, v. 99, no. 16,359, p. 4.

The Evening Post, 1906a, Circuit of shaken region: New York, N.Y., April 20, 1906, v. 105, p. 3.

-1906b, Destruction a t Alameda: New York, N.Y., April 19, 1906, v. 105, p. 2.

-1906c, March of conflagration. Sinking of waterfront: New York, N.Y., April 19, 1906, v. 105, p. 6.

-1906d, Shock felt a t Stockton: New York, N.Y., April 18,1906. -1906e, Railroad tracks sunk: New York, N.Y., April 18,1906,

v. 105, p. 1. Evening Sentinel, 1906a, Most terrible and destructive earthquake:

Santa Cruz, California, April 18, 1906, v. 10, no. 269, p. 1. -1906b, Earthquake notes: Santa Cruz, California, April 19,

1906, v. 10, no. 270, p. 2. ----1906c, Personals, Moss Landing Watsonville: Santa Cruz,

California, April 19, 1906, v. 10, no. 270, p. 6. -1906d, Earthquake notes: Santa Cruz, California, April 19,

1906, v. 10, no. 270, p. 8. -1906e, Earthquake paragraphs: Santa Cruz, California, April

20, 1906, v. 10, no. 271, p. 3. The Evening Wisconsin, 1906, Big crevasse in street: Milwaukee,

Wisc., April 18, 1906, v. 59, p. 1. Fallows, Samuel, 1906, Complete story of the San Francisco horror:

San Francisco, Hubert D. Russell, 408 p. The Ferndale Enterprise, 1956, Enterprise tells of big quake:

Ferndale, Calif., April 20, 1956, v. 78, no. 16, p. 1, 3.

CITED 69

Gilbert, G. K., 1906, Photographic collection; from United States Geological Survey Library Archives, Denver, Colorado.

Gilbert, G. K., Humphrey, R. L., Sewell, J. S., and Soul;, F., 1907, The San Francisco earthquake and fire of April 18, 1906 and their effects on structures and structural materials: U.S. Geol. Survey Bull. 324, 170 p.

Givens, J. D., 1906, San Francisco in ruins: San Francisco, Califor- nia, Leon C. Osteyee.

Hall, W. H., 1906, Some lessons of the earthquake and fire; 11, A record of earthquake disturbances: San Francisco Chronicle, v. 88, no. 125, p. 32.

Halley, William, 1876, The Centennial year book of Alameda County, California: Oakland, p. 257-269.

Hansen, W. R., 1966, Effects of the earthquake of March 27,1964 a t Anchorage, Alaska: U.S. Geol. Survey Prof. Paper 54%A, p. A59-A66.

Harding and Associates, 1964, Soil investigation, Mission Street line, San Francisco Bay Area Rapid Transit District: Harding and Associates, San Rafael, Calif,, unpub. rept., Soil Inv. M-701, 10 p. and numerous plates.

Himmelwright, A. L. A,, 1906, The San Francisco earthquake and fire: New York, The Roebling Construction Ca., 270 p.

Hittel, J. S., 1878, A history of the city of San Francisco and inciden- tally ofthe State of California: San Francisco, A. L. Bancroft and Co., 1878, 498 p.

Holden, E. S., 1898, A catalogue of earthquakes on the Pacific Coast, 1769-1897: Smithsanian Inst. Misc. Colln., v. 37, no. 5, 253 p.

Huber, W. L., 1930, San Francisco earthquakes of 1865 and 1868: Seismol. Soc. America Bull., v. 20, no. 4, p. 261-272.

The Humboldt Times, 1906, Earthquake in Eureka- Some funny stunts; Damage in the north: Eureka, Calif., April 19, 1906, v. 633 "0.92) P. 5.

-1954a, Earthquake damages mounting: Eureka, Calit, Dec. 22, 1954, v. 174, no. 304, p. 13. - 1954b, Eel River Valley damage severe; Quake damages

mount: Eureka, Calif., Dee. 22, 1954, v. 174, no. 304, p. 1, 22. ----1955, Remember the earthquake?: Eureka, Calif., Dec. 20,

1955, v. 75, no. 302, p. 17. Hyde, C. G., 1906a. The structural, municipal and sanitary aspects of

the central California eastastrophe, pt. 11: Eng. Rec., v. 53, no. 23, p. 70lL705.

-1906b, The structural, municipal and sanitary aspects of the central California catastrophe, pt. 111: Eng. Rec., v. 53, no. 24, p. 737-740.

-1906c, The structural, municipal and sanitary aspects of the central California catastrophe, pt. IV: Eng. Rec., v. 53, no. 25, p. 766769.

Jordan, D. S., ed., 1907, The California earthquake of 1906: San Francisco, A. M. Robertson, 360 p.

Kachadoorian, Reuben, 1968, Effects of the earthquake of March 27, 1964, on the Alaska Highway system: U.S. Geol. Survey Prof. Paper 545C, 65 p.

Lawson, A. C., and others, 1908, The California earthquake of April 18, 1906; report of the California State Earthquake Investiga- tion Commission: Carnegie Inst., Washington, pub. 87, v. 1 and atlas, 451 p.

Leslie's Weekly, 1906a, The earthquake's havoc in San Francisco's suburbs; immense damage wrought in, Oakland by the severe seismic convulsion which drove all the people of that city in terror from their homes: New York, N.Y., May 3, 1906, v. 102, no. 2643, p. 416.

----1906b, San Francisco's season of suffering and gloom: New York, N.Y., May 10, 1906. v. 102, no. 2644, p. 447.

-1906c, First panorama ~ h o t o ~ r a p h s of fire-scarred 'Frisco:

REFERENCES CITED 71

Sprague, Malcolm, 1941, Supplementary climatic notes for Califor- nia, in Climate and Man: U. S. Dept. Agriculture, p. 79S797.

Steinbrugge, K. V., Bush, V. R., and Zacher, E. G., 1959, Damage to buildings and other structures during the earthquake of March 22, 1957, in San Francisco earthquakes of March 1957: Califor- nia Div. Mines and Geology Spec. Rept. 57, p. 73.106.

Sunday Mercury and Herald, 1906, Seventeen men buried a t 1 . 0 ~ ~

Prieta: San Jose, Calif., April 22, 1906, no. 112, p. 3. Sunday Record-Herald, 1906, Twain tells humors of 1868 earth-

quake: Chicago, Ill., April 22, 1906, v. 25, no. 50, p. 7. Taber, S., 1906, Some local effects of the San Francisco earthquake:

Jour. Geology, v. 14, no. 4, p. 303.315. Townley, S. D., and Allen, M. W., 1939, Descriptive catalog of earth-

quakes of Pacific Coast of the United States 1769 to 1928: Seis- mol. Soc. America Bull., v. 29, no. 1, p. 21-252.

U.S. Weather Bureau, 1912, Summaries of climatological data: U.S. Dept. Agriculture Bull. W., v. 1, see. 1-57.

Varnes, D. J., 1958, Landslide types and processes, in Landslides and engineering practice: Natl. A d . Sci., Natl. Research Board Spec. Rept. 29, NAS-NRC Pub. 544, p. 2&47.

Vames, D. J., 1978, Slope Movement Types and Processes, in Land- slides: Analyses and Control, Transportation Research Board, Special Report 176, Chapter 2.

Weatherbe, D'Arby, 1906, Effects ofthe earthquake: Mining and Sci. Press, v. 92, no. 24, p. 402.

Weekly Humboldt Times, 1906a, Damage in the country: Eureka, Calif., April 26, 1906, v. 53, no. 17, p. 3.

-- 1906b, Local phases of disaster; Earthquake sufferers; no title: Eureka, Calif., April 26, 1906, v. 53, no. 17, p. 5. - 1906c, Petrolia badly hit: Eureka, Calif,, April 26, 1906, v. 53,

no. 17, p. 6. Wood, H. O., Allen, M. W., and Heck, N. H., 1939, Earthquake his-

tory ofthe United States; Pt. 11, California and western Nevada: Coast and Geodetic Survey, No. 609r 25 p.

Wood, M. W., 1883, History of Alameda County, California: Oakland, M. W. Wood, 1001 p.

Youd, T. L., 1913, Liquefaction, flow, and associated ground failure, U.S. Geol. Survey Cire. 688, 12 p.

1975, Liquefaction, flow and associated ground failure: Natl. Conf, on Earthquake Eng,, Ann Mieh,, June 1975, Proc., p. 146155.

youd, T, L,, and H ~ ~ ~ ~ , S, N,, 1976, ~~~~~f~~~~~~ during 1906 sari Francisco earthquake: Am. Soe. Civil Eng., Jour. Geotechnical Div., v. 102, no. GT 5, May 1976, p. 42S439.

YOU^, T. L., Nichols, D. R., Helley, E. J., and Lajoie, K. R., 1975, Liquefaction potential, in Studies far seismic zonation ofthe San Francisco Bay region: U.S. Geol. Survey Prof. Paper 941-A, p. 68.74.

Zeigler, W. G., 1906, San Francisco and vicinity, the story of the great disaster, April 18 to 21, 1906, told by pen and picture: San Francisco, California, Leon C. Osteyee, 22 p., 100 illustrations.

TABLES 5-9; FIGURES CITED IN TABLES

74, HISTORIC GROUND FAILURES IN NORTHERN CALIFORNIA TRIGGERED BY EARTHQUAKES

TABLE 5 . S p e c i f i c descriptions ofg~~u&fa&~+r~ in the Monterey Bay counties region . . - -.

Location number is assigned t o each reported ground-failure s i t e . Corresponding numbers are found on p l a t e 1. Figure number re fers t o f igure i n t h i s repor t showing damage described under "Quotation" column. Failure type i s indicated by t he following symbols. Corresponding symbols are found on p l a t e 1 . .* ...

Hil l s ide landslides including ro t a t i ona l slumps, ... . . . River s t re tches with extensively f i ssured flood block glides, debr i s avalanches, and rockfa l l s : pla ins ; pa t t e rn indica tes s t r e t che s of r i v e r

affected and not width o f disturbed zone @ Streambank landslides including ro t a t i ona l slumps. " ,r

and s o i l f a l l s : 0 Sand bo i l s

+ Lateral spread ' @ Disturbed wells

M Ground set t lement ! 0 Absence of ground f a i l u r e noted

Ground cracks not c l e a r l y associated with land- i Miscellaneous e f f e c t s s l i de s , l a t e r a l spreads, settlement or primary f a u l t movements i *Arrows showing extent of area affected. ) ; ,,.~ I,'. . -. Symbol shows f a i l u r e type

Arr~%rarv w i f h w h i c h f a i l ~ ~ r e ~ i f e s c m he located i s viven as follows: A. a s i t e t ha t can be accurately re loca ted ; B, a

Loca- Fig- Fa i l - Accu- Year of Reference t ion ure ure ra- earth- No. No. type cy quake

Quotation

1 X B 1906 Lawson and others, The railway s t a t i o n a t Bradley, s tanding on made ground, s e t t l e d 1908, ! inches ..atm....e%+ p. 298.

2 X C 1906 Lawson and others, At San Arda * * * the r i v e r bed i s thought t o have sunk about 2 . 5 1908, f e e t , tho evidence of t h i s was not obtained. p. 298.

@ C 1906 Lawson and others, A t San Ardo, quicksand was thrown up i n a w e l l , :e$?ing t o lessen 1908, the flow cmsmderably. p. 409.

3 B 1906 Lawson and others, (S. A. Guiberson, Jr.)--As superintendent of t he pipe l ine , I am 1908, i n a pos i t ion t o say t ha t we have no breaks whatever i n any place

+izP p. 297. between Coalinga and t he Sa l inas r i ve r , and there were no f i s su r e s of any kind along the l i ne between these poin ts . This I know pos i t ive ly , as I have l i n e r i d e r s who were ins t ruc ted t o look c lose ly f o r any disturbance o f t h i s nature. The l i n e of f i s su r e s seems t o have ended nor th of P r i e s t Valley.

4 .X C 1906 Lawson and others, * * t h e Sa l inas r i v e r bed sank near ly 6 f e e t a t King City, and 1908, ( t h e wide sandy bottom a t Three Mile F la t was much cracked * * * . p . 293.

C 1906 Lawson and others, The river-bed sank nearly 6 f e e t i n t he v i c i n i t y of King Ci ty . 1908, p. 297.

5 @ C 1906 Lawson and others, Priest VaZZey. + * There were s l i g h t landslides and cracks 1908, along the edge of t he creek banks. p. 291.

C 1906 Carey, * * A t P r i e s t Valley * * * f i s su r e s i n the ground [were] 1906, reported. p. 297.

TABLES &9

TABLE 5.Specific descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i o n "re "re ra- earth- No. No. type cy quake

Quotation

6 C 1926 Tomley and Allen, 1926 Ju ly 25. 9:58 a.m. VII. Near Idr ia , San Benito Co. This 1939, shock caused rocks t o r o l l down h i l l s i d e s i n t he Idria-Panoche p. 241. region * r * - .-

7 B 1906 Lawson and o thers , Cantua Creek, hresno County (S. C. L i l l i s l . The shock was severely 1908, f e l t i n t h i s region, and i t s d i r ec t i on was southeast-northwest.

+a+ p. 319, A s e r i e s o f landslides caused by the~earth-were reported by p l a t e 1256. ~ r . illi is , - ~ j i t ~ i i a i ~ ~ f i ~ ~ ~ f h ~ 1 ; G - &-?:isY~. 14 E . ,

h1.D.M. t o the middle pa r t of T. 15, R. 11 E . , a distance of about 23 miles. The fea tures were not a t f i r s t recognized by M r . L i l l i s as landslides, and as they occurred on the e a s t s i de o f t he Coast Ranges, on the border of a port ion of t he San Joaquin Valley, where the i n t e n s i t y was abnormally high, t hehypo the s i s was entertained t ha t t he r e might have been a supplementary f a u l t i n t ha t region along the edge of t he mountain range. The remarkable alinement of the fea tures l e n t support t o t h i s suggestion. The region was, however, subsequently v i s i t e d by Prof. G. D. ~ouderback: i n company

, . with Mr. L i l l i s , and t he fea tures reported by t he l a t t e r were found t o be landslides. Professor Louderback furnishes t he following note regarding them:

The phenomena reported by Mr. L i l l i s are several landslides. In each case t he e f f e c t o f t he movement can be followed i n d e t a i l and sharPly delimited. The form of t he mo~ed body is typ i ca l l y t ha t of t he lands l ide i n each case, with the c l i f f a t the upper end curved and concave toward t he lower pa r t o f t he sldpe. .The mass has moved away and downward, leaving i n some instances an open space o r f i s su r e , p a r t i a l l y f i l l e d a t t he present time (May, 1907) by caving. The back c l i f f s , followed around, gradually pass i n to l a t e r a l planes. o f movement, which themselves are sometimes gaping on t he more elevated s ide , showing a forward and s l i g h t l y l a t e r a l movement o f the mass. (See p l a t e 1258.) No general f i s su r e , f au l t , o r r i f t was observed passing t h ru o r

near these landslides, a l tho a careful search w a s made fo r such fea tures . I suspected a t f i r s t t h a t there might be such a r i f t - l i n e , because t he landslides are approximately along one l i n e or b e l t . This appears, however, t o be due t o t he f a c t t h a t one pa r t i cu l a r formation is espec ia l ly favorable t o landsliding, a l l the s l i d e s t h a t I saw along t he lower p a r t of the range being associated with a th ick reddish-brown sha le o f a d e f i n i t e s t r a t i g r aph i c horizon (Tejan?). The general s t r uc tu r e of the range causes the rocks o f any given horizon t o outcrop along a l i n e roughly p a r a l l e l t o t he range f ront (approximately northwest-southeast). The lands l ides a l l lookt f resh , and according t o Mr. L i l l i s several o f t h e m (and probably a l l of those under consideration) were caused on April 18, 1906. I made a t r i p across the hi115 from the va l ley t o New I d r i a and noted nothing t ha t appeared t o be a recent seismic l i ne .

. . . 8 ... , , C 1906 Lawson and others, * * * t h e southernmost extension of continudus cracks along t h e ' .

1908, [Salinas River] bank was found t o be about 2.5 miles south of p. 293. Gonzales bridge. From here t o the mouth of the r i v e r t he cracks

are p a r a l l e l with t he r i v e r banks. ,

9 A 1906 Lawson and others, The movement a t Gonzales bridge was mostly on t he west bank o f . , 1908, t he stream. A wire fence trending nor th and south wassfn.6

p. 293. inches apar t here, and wooden p i l e s a t t he southwest end of the bridge, s a id to-Ee driven down 75 f e e t , have been t a r n loose and mved from-plumb, t h e i r o r i g ina l upright pos i t ion . At t he north- eas t end o f the bridge t he p i l e s are undisturbed, but t he surface s o i l and a wire fence have moved r e l a t i v e l y 18 inches northward. (See f i g . 59.) [That f igure, no t reproduced i n t h i s repor t , shows a plan view of t he bridge and approximate r e l a t i v e movements of t he p i e r s . ]


TABLE 5 .Spee i f i c descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t i on "re "re ra- earth- No. No. type cy quake

North o f Gonzales bridge the f i s su r e s are mostly on t he west s i de of t he stream channel, and reach a maximum width of 18 inches. No evidence o f shearing could be found.

C 1906 Satinas D d t y Index, EARTH CRACKED AT GONZALES. Albert Hansen came t o t he Index t h i s 1906b. m m i n g . He had come from Gonzales. The bridge there was broken

a t t he fur ther end, and large areas of land opposite Gonzales across the r i v e r were under water. The r i v e r bed has opened and for miles t he ear th is cracked open from inches t o f e e t i n i r r eg - u l a r cracks.

10 +o+ C 1906 Lawson and others, I n the creek bottoms west of Chualar, sand c r a t e r l e t s begin t o 1908, appear and become numerous along t he s t r e an northward. p. 293.

C 1906 S t D o I d , STOPPED THE TRAIN. Passenger t r a i n no. 3 was near Chualar when 1906a. t he shock occurred and t he engineer says t h a t t he t rack moved back

and for th with a worm-like movement.

11 B 1906 Gilbert , Humphrey, The road leading t o Spreckels 's sugar m i l l , 4 miles south of + Sewell, and Soul€, Salinas, was a l so g r ea t l y damaged by t h e i p s . Spreckels 's 1907, sugar m i l l (PTTX1I;A)-iSsiFZZt-ft alluvium. P. 21, p l a t e XII,A.

B 1906 Duryea and others, From the Sa l inas highway bridge t o Spreckels, a distance of about 4 1907, 1 112 miles, the sur.f>.c.e_ of t he ground w ~ ~ . c a ~ ~ e d . . s . o O r n ~ ~ ~ a t

p. 311. the ,??adway b e c a ~ e . ; ~ ~ ~ ~ ~ f o ~ l e ~ s . ~

B 1906 Lawson and others, South o f the Spreckels factory, the low bottom-land between t he 1908, banks of the r i v e r i s considerably cracked, although there is no p. 295. prominent ve r t i c a l dropping of t he land along the cracks. This low

land l i e s west of t he present course of the stream, and i s i n t e r - sected by sloughs and former water courses. A l ~ . ? , f u , > h e _ g * ~ i s of a deep sandy nature, consequently it was much disturbed and f i ssured by the quake, and the f i s su r e s becT<<~fi?i<d:G~~~~.water and sand forming quicksand,~~~?s~WEttt5~S f r equen t l y being sF."tzd.;iiti; iiy. ..Nbo"e <<<i;ea rlupp -The posi-

t ' in'~bfthgc7a'cks' is now marked by patches of l i g h t , bluish-gray sand i n t he f i e l d , from the drying out of the quicksands. Houses on t h i s low land were thrown out o f plumb, and chimneys were destroyed. The cracks diminish i n number as one goes southward, and p r ac t i c a l l y end i n the v i c i n i t y of t he Gonzales bridge.

and o thers , The ground [a t Spreckels sugar m i l l ] t o t he south had besz_mu!h hk=ried-y$<d ~thherYl~le-deforme~d, z?"s=-?g t he wrecking of i r i s t le ; , pumping-house, and o the r s t ruc tures . F h e F v , e 3 F k - a t the rear of the buildin. were oul led aoar t . due orobablv t o the slumo- . ing of t@,,gra,md toward in 6 ; d ' ~ l o u d ' o f th'e river.

1n t he bottom of t h i s slouxh water gushed fo r t h at numerous places a t t he time o f the earthquake; I t is s a id by those who witnessed t h i s phenomenon t ha t the water spurted repeatedly as high as 20 f ee t , and t ha t t he outf15C"jbf'~~<~FTZ5fSddfo-i-iCC iiiniite<CfteF'fhe shock. The places where t he water spurted fo r t h are marked by areas of f ine , l i g h t , bluish-gray sand, which i s sa id t o be known only a t a depth of 80 f ee t i n the various well borings of t he v i c in i t y . In these areas of f i ne b lu ish sand are of ten funnel-shaped depressions o r c r a t e r l e t s from which the water issued.

B 1906 Lawson and others, Near Agenda, [about 3 m i (5 km) southeast o f Spreckels and about 1908, 112 m i (.8 km) northeast o f Buena Vis ta School] i n the lowlands,

+ 0. 293. i s a cracked area near lv a mile from the r i ve r . orobablv alone an ~ ~ , ~ ,. ~~- a ,~ - old water course: while sand c r a t e r l e t s are sca t te red t h ru the orchards. At Spreckels t he movement caused much damage t o flumes, sewers, and water-mains; and from here t o Blanco t he deep s o i l of the adjacent f i e l d s i s much cracked and i n places sunken and dotted with sand c r a t e r l e t s .

TABLES 6 9 77

TABLE 5 , S p e c i f i e descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t i o n "re ure ra- earth- No. No. type cy quake

+ @I1.' 1906 Derleth, There i s a l so a rupture i n the car r iage way t o t h e dumps, c lear ly 1906d, showing t he existence o f a decided ground Kvement a t t he time of p. 712. t he earthquake.

B 1906 SaLinas Daily Indeh AT SPRECKELS * * *. The t r e s t l e o f t he elevated railway, upon C b 1906a. which i s conveyed t he lime rock, is about three f ee t out o f l i n e

p. 1. and t he r a i l r oad t r a ck t ha t leads t o t he Spreckels bridge across t h e r i v e r was twisted i n to the shape of an in te r rogat ion poin t .

12 ... . . . ... B 1906 Lawson and others, (A. S. Eakle.1--The effect of the earthquake upon t he alluvium was 1908, well shown along the banks o f t he stream from the Sa l inas t o t he p. 295. Gonzales bridges. Along t he e a s t s i de o f t he r i v e r for a shor t

8 d is tance south of the Sa l inas bridge, 4 miles south of the town, * t h e land is =backed a t t he edge of t he bank, t he cracks pa r a l l e l i ng the course of t h e r i v e r ; but comparatively l i t t l e cracking w a s observed on t h i s s i de o f t he r i ve r . Along t he bank and down i n t he river-bottom i t s e l f , on the western s i de of t he stream. f i s su r e s were very prominent: The county road southward from tho Salinas bridge runs along the embankment about 10 t o 20 f e e t above t he stream bed. The road i s an o i l ed one. and the o i l had formed a

10 A 1906 Lawson and others, 1908, + p. 296, p l a t e 123A.

B 1906 Lawson and others, 1908, p. 297.

hardpan upon the underlying sand. In t he v l c l n l t y o f the brldge the road has been sha t te red by t he quake fo r a d is tance of ZOO yards. The breaks are i n t h e na tu r i of a caving i n of t he road on the north s i de of t he crack, as i f hollow spaces existed beneath, leaving a ve r t i c a l escarpment on the south side. The main sinking i s a t t he most southerly f i s su r e . Here t he road has sunk bodily t o a depth o f 10 f ee t , leaving a high ve r t i c a l bank diagonally across t h e road, and t h i s sunken area extends f o r some distance i n to t he adjoining f i e l d an t he west. There is no,upheaual of the road i n any place t o compensate f o r the sinking.

At t he bridge, a large t russed s t r uc tu r e i n 2 spans having a bearing of N. 27- E., t h e south p i e r , cons is t ing of 26 p i l e s incased i n plankinZwTS th ru s t t o the south [ r e l a t i ve t o northward movement o f g r o w ] b .Fen .6 a n d l f e e t , so t h a t t he e n t i r e p i e r was incl ined as shown m p l a t e 123A. The p i l e s were not broken a t t he ground leve l . The north and middle p i e r s were apparently not affected. An o i l pipe which cros t t he bridge was buckled and t w i s t - ed a t t he south end of the bridge, and when t h i s was repa i red t he pipe was found t o have been shortened 7 f e e t . The pipe l i n e extends from the San Joaquin Valley t o t he Bay o f Monterey. A few hundred yards t o t he south of the bridge is a pumping s t a t i on , and a t t h i s point some of the connections of the pipes were broken and d is - placed. The d i rec t ion of t he shortening of t he bridge span and the pipe i s roughly normal t o t he d i rec t ion o f the San Andreas R i f t , on t he o the r s ide of the Gavilan Range. Mr. S. A. Guiberson, superintendent o f the l i n e , r epo r t s t h a t the pipe was broken i n about twenty places i n the v i c i n i t y o f t he r i v e r , a n d t h a t a t some o f these breaks t he pipe was pulled apar t .

(S. A. Guiberson, J r . ) - -* * * The conditions preva i l ing along t he Sa l inas River, and some o f t he pecul ia r cipcumstances at tending the breaking of our [o i l l i n e i n about twenty are of i n t e r e s t . I was on t he ground t h e follgwing day, and only r eg r e t tha t I d id not have time t o have some o f t he pecul ia r fea tures photographed. In places our l i n e had been broken and the ends were 3 f e e t apar t ; a t t he same time t he ends o f t he pipe would be hammered up, showing t h a t there had been an opening and closing movement a t t h a t point , while a t o the r points the l i ne would over- lap as much as 4 f e e t . One o f our s t a t i ons i s i n t h i s zone of disturbance, and t he engineers, being on duty, had an excellent opportunity t o see what most of us who were i n bed merely f e l t . They s t a t e t ha t these f i s su r e s were opening and closing, and t h a t t he water and sand would go 20 f ee t i n the a i r as they closed.


TABLE S.*pecific descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fail- Aceu- Year of Reference i Quotation t i on ure ure ra- earth- No. No. type cy quake

A 1906 Lawson and others, The county bridge south of Sa l inas was rendered unsafe by t he move- * 1908, ment of t he p i e r s a t t he southern end. (P la te 123A.) On t he west p. 293, bank near the bridge a s e r i e s of peculiar cracks have t o rn up the p l a t e 123A, road and adjacent f i e l d , along what is probably t he path o f an old p l a t e 136, water course. These are shown i n p l a t e s 136, 137. p l a t e 137.

A 1906 Lawson and others, On the road eastward t o Sa l inas from Del Monte, no v i s ib l e s igns 1908, of the earthquake were encountered u n t i l t h e Sa l inas River was + p. 292. reached. The Sa l inas bridge was moved southerly severa l f e e t ,

according t o repor t , and t he framework was broken s o as to . render t he bridge unsafe.

A 1906 Duryea and others, Fig. 1, P la te LV, shows the south abutment of the Sa l inas bridge. + 1907, The ground a t t h i s point moved about 6 f t . i n t o the r i ve r , . . .. p. 311. A 3-in. o i l pipe l i n e which crossed the bridge was ruptured on the

south approach, one length of pipe being bent i n the form o f t he l e t t e r S. The northern approach t o the bridge was not affected.

A 1906 Gilbert , Humphrey, The a l l uv i a l o r so f t s o i l forming the banks of r i v e r s generally + Sewell, and Soule, moved toward the r i v e r under t he earthquake v ibra t ions , t he s e t - 1907, t l i n g of t he ground being most marked (PI. VIII, B). The country P. 21, i n t he v i c i n i t y of Sa l inas River presented i n t e r e s t i ng fea tures p l a t e VII1,B. of t h i s character . The county road crosses t h e r i v e r near Sa l inas

on a wooden bridge, and the slippxng of the banks car r ied t he south abutment 6 fee t toward t he r i ve r . The ground was badly cracked and

@ there were a number of s l i p s i n t he neighborhood.

A 1906 Derleth, The land on the south bank of the Sa l inas r i v e r f o r a considerable + 1906d, area has moved i n t o the r i v e r i n a nor ther ly d i rec t ion , on an aver- p. 712. age, through a distance of about 6 f t . Figs. 15 and 16 show the

south abutment of t he Sa l inas highway bridge. The ground has moved under the super-structure about 6 f t . , bending t he p i l e bent foundations as shown i n t he p i c tu r e s without ser ious ly i n ju r i ng t he t russes . A 3-in. o i l pipe-l ine crossing t he bridge was ruptured on t he south approach, one length of pipe being bent l i ke t he l e t t e r "S." The northern end and approach t o t he bridge were hardly affected. In f ac t , t h e northern bank of t he r i v e r shows l i t t l e disturbance a t t h i s point . From the Sa l inas bridge eastward a distance of about 1 1/2 miles t o Spreckels, t h e south bank of the r i v e r i s continuously scarred and r en t $0 t h a t the o ld road is impassable f o r vehicles.

B 1906 Monterey County The Sal inas County Bridge a t Hilltown i s reported unsafe. The M Dmocrat, ear th t h i s s ide of the r i v e r sank about four f e e t and the approach + 1906, on t he o ther s ide moved some f i ve f e e t from i t s former pos i t ion .

p . 2. * * * On the Buena Vis ta s ide a f i s su r e four f e e t wide and of unknown depth extends f o r severa l hundred fee t . Near Agenda the

0 ear th opened twenty f i ve f ee t across from which gushes a stream o f cold water completely s a tu r a t i ng and covering t he neighborhood.

B 1906 Montereg County Near the county bridge across t h e r i v e r j u s t opposite t he fac tory r Democmt, [Spreckels] t he ear th i s depressed i n some places twenty-five f e e t

1906, and extends back i n to the h i l l s several hundred f ee t . * * * p . 2. The ear th has a l so sunk i n many places along t he r i v e r bank on both

s i d e s o f the Sa l inas r iver .

B 1906 S a Z i ~ s WeekZy Hiram Corey, of Las Palmas ranch across t h e Sa l inas r i v e r , had t o Ide z , came t o town today on horseback, because of the impass ib i l i ty of 1906, t he roads. At h i s place no damage was suffered except t he toppling x p. 1. over of some chimneys. Mr. Corey repor ts t h a t there is a depres-

s ion of ten f ee t f o r a quar te r of a mile a t t he Jacks prune orchard. The road is impassable and he had t o make a detour i n t o t he orchard t o get i n t o town. He repor ts t ha t the sediment land a t Spreckels and i n f ront of Las Palmas, which was dry yesterday, i s flooded today, and t ha t t he county's i ron bridge a t Hilltown i s out of comiss ion f o r teams.

TABLES &9 79

TABLE 5.Specif ic descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on ure ure ra- ear th- NO. No. type ey quake

Quotation

-

1906 Satinas DaiZy Indez; BRIDGE CONDEMNED. The county bridge across t h e r i v e r suffered 1906a. badly and had been closed t o t r ave l by order of supervisor J . A. p. 1. Hughes. The heavy p i l i ng i s thrown ten fee t out of alignment and

the timbers were snapped off as though they were toothpicks. The approach a t t he south end has been l i f t e d about three f e e t and by the force of t he temblor has been shoved s i n f e e t southward. The bent supporting the approach was snapped off and the long approach 1s suspended, making it unsafe f o r t rave l .

GREAT FISSURE OPENS. A pecul ia r freak of the quake i s t he deep f i s su r e t ha t crosses t h e county road and continues through the f i e l d s along through Blanco [loc. 131 almost t o t he mouth of the Sa l inas r i ve r . This i s a depression in t h e ground ranging i n width from near ly a hundred yards a t t h e crossing of the road t o f i f t e e n fee t out i n the f i e l d . In t rave l ing t he road a f t e r turning toward the bridge from Hilltown, one i s suddenly confronted with a pree i - pice s i n f e e t i n height. The ground has sunk and a f t e r climbing down the embankment t he ear th is torn and r iven , showing how grea t must have been the force of t he shock. A port ion of the high embankment across t h e r i v e r has caved i n and gone out of s ight . At another place there i s another deep f i s su r e , through which water and quick sand oozes.

1906 LawSon and others, Between Blanca and Neponset t he cracking and s e t t l i n g of t he law 1908, land flooded the adjacent f i e l d s and gave r i s e t o s t o r i e s about the p. 295. Sa l inas River having r i s en severa l f e e t . The "boil ing up" of the

water t h ru sand c r a t e r l e t s was a lso soon d i s t o r t ed i n t o a s t o ry about t he water of t he Sa l inas River being boi l ing hot.

1906 Chicago Evening Between Seaside and Del Monte t he t racks have s e t t l e d f u l l y four American, f e e t and the r a i l s have been twisted a l l shapes. [See a l so loc. 1906, 16 for adjoining tex t . ] p. 3.

1906 Lawson and others, I t may be sa id , regarding t he s o i l movement along these streams, 1908, t ha t along t he Salinas River from Gonzales t o near Blanco, every- p. 294. thing shows a movement down the r i ve r . From Blanco t o Neponset

the movement seems t o have been a s e t t l i n g of the a l l u v i a l mate- r i a l s , while from Neponset t o the mouth of the Pajaro River [see loc . 201 t he ground ( i n severa l p laces , a t l e a s t ) moved eastward o r inland.

1906 Satinas DaiZy Inder, The bridge a t Neponset is wrecked out of l i ne and although it is 1906d. i n use r epa i r s w i l l have t o be made on the same as soon as laborers

and material can be obtained.

1906 Lawson and others, At Neponset and Sa l inas t he p i l i ng under t he county bridge was 1908, moved i n same of the bents a t l e a s t 10 f e e t toward the r i ve r . A p. 293. sec t ion man who stood i n t he midst of t he cracks a t t he end of t he

Neponset bridge was drenched with spur t ing water.

1906 Lawson and others, Both the railway and county bridges a t Neponset were moved, t he 1908, northern concrete p i e r s of the former 2 inches e a s t and t he cen- p. 293. t r a l wooden p i e r of the l a t t e r apparently 4 f e e t south.

1906 Lawson and others, From Morocoho [~ashua ] t o Moss Landing f i s su r e s r a r e l y show i n 1906, the marshy land, but t he narrow gage railway t rack has been sh i f t ed p. 293. a few inches i n several places.

Between Cas t rovi l le and Monterey the ground is s a i d t o have opened and shut and mud t o have spurted from the f i ssures .


TABLE 5.Specif ic descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference t i on ure ure ra- earth- No. No. type cy quake

Quotation

C 1906 Chicago Everring Watsonville, Cal. April 19.--As we passed through the country American, between Monterey, Cas t rovi l le and Tajaro [sic] we saw unmistakeable 1906, signs of t he t e r r i f i c wrenching given t o t h a t sec t ion by yesterday's p. 3. tremendous uphevals of t he ear th .

Great s inks, extending along t he t racks as f a r as t he eye could I reach and ranging from four t o s i x f e e t i n depth, have been l e f t i n

the surface of t he ear th , a mute testimony of the awful twis t ing and wenching of the i n t e rna l forces. For distances of from one- quar te r t o three-quarters of a mile the road bed has dropped from

I four t o s i x fee t .

MUD GEYSERS EXCITED INTO SUDDEN ACTION. Between Cas t rovi l le and


1906 Chicogo Evening American.

1906 Sun Jose HernZd, 1906s. p. 5.


Monterey, along t he r a i l r oad t racks and i n t o the f i e l d s , mud geysers have been excited i n to acrian spouting a bo i l i ng ho t , b lu ish , shale-colored mud t o a h eighth [ s ic1 of from ten t o twelve fee t . . .

In places these geysers ar; from four t o ten f e e t apar t and i n o ther sec t ions they are f i f t y f e e t or more apart . At Fairman Section Foreman H. J. Hall and Roadmaster Goldman saw

these geysers i n v io len t act ion. The mud was spouted through the sand and lorn. I saw t h i s mud

along t he t racks fo r severa l miles, with here and there places where the geysers had been recent ly a t work. The r a i l r oad t racks f o r almost t he e n t i r e distance are twisted

out of a l l semblance of tracks. Between Seaside and Del Monte the t racks have s e t t l e d f u l l y four

fee t and the r a i l s have been twisted a l l shapes. [See lac . 14.1

Cas t rovi l le , being on so l i d ground, was not ser ious ly affected.

CREVASSE OPENS AND CLOSES I N THE EARTH. Near Cas t rovi l le , while t he disturbance was a t i t s height , Foreman H. J. Hall grabbed h i s two children and l e f t the sec t ion house. AS they passed through the door they saw t h e ear th open and a crevasse, which Hall described as f u l l y s i x f e e t wide, open and close severa l times. I v i s i t e d t he scene a t midnight and found t he sec t ion house stand-

ing i n a pool of geyser mud. This mud was l i k e quicksand, and of unknown depth.

r r The LePoncet [ s ic ] bridge [see loc. 151 i s i n bad condition. The J a j a r a [ s i c , see loc. 24, 251 bridge i s gone. Cas t rovi l le bridge is i n a bad condition. There has been a heavy s l i d e a t Newria [sic, see loc . 61 besides severa l o ther t r i f l i n g damages.

Prunedate. (H. H. McIntyre).-- * r * Water s t a r t e d flowing i n many places where there had been n o n e , o r but l i t t l e before. There were 2 small landslides from springy places, the d i r ec t i on of the $ l i p being from north t o south.

19 C 1906 Lawson and others, At Moss Landing, where t he r i v e r runs p a r a l l e l with the shore 1908, l ine [ the Sa l inas River disharged i n t o t he ocean north of Moss p. 293. Landing i n 19061, the s t r i p of land is seamed fo r miles. A + crack, o r r a t he r a s ink , about 20 f ee t wide and 4 or 5 f e e t deep

ran under the buildings and r en t them asunder. The o f f i c e building between t h i s crack and t he r i v e r has been moved bodily--land and all--about 12 f ee t toward t he r iver . Some of the cracks run i n to t he ocean.

TABLES L 9 81

TABLE 5 .Spec i f i c descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t i on ure "re ra- earth- NO. NO. type cy quake

B 1906 Lawson and o thers , A t Moss Landing many small cracks occur i n the mud on t he west s ide 1908, of the r i ve r , and t he condition o f the wharf ind ica tes an eastward + p. 293, movement of the sand-spit. (See p l a t e s l 3 4 B , 135A, B.) I t i s p l a t e 1348, reported t ha t a t places along t he p i e r where the water w a s formerly

17.A p l a t e 135A, 6 f e e t deep, it now has a depth of 18 o r 20 fee t . p l a t e 1358.

B 1906 Lawson and o thers , Along the beach o r sand-spit which separates t he Salinas River from + 1908, t he Bay of Monterey a t Moss Landing, there was a marked lurching o f p. 401, t he s p i t toward t h e t rench of t he r iver as i l l u s t r a t e d i n p l a t e s

12B p l a t e 134A. 134A, B and 135A, B.

B 1906 Lawson snd others, The wharf a t Moss Landing buckled up and pa r t l y collapsed, while 1908, the warehouses were wracked or f e l l westward. p. 292, p l a t e 1160.

+ B 1906 Gilbert , Hwnphrey, Along t he Bay of Monterey the whole share sl ipped about 12 f ee t Sewell and ~ a u l 6 , in to the bay, the movement buckling the r a i l s on a r a i l r oad t r e s t l e

M 1907, and t he ears dropping about 5 f e e t . A frame house and surroundings p. 21. moved 12 f ee t , s t i l l maintaining t h e i r r e l a t i v e posit ions. [This

occurred a t &loss Landing where the movement was i n to the Salinas River ra ther than i n to t he bay.]

1906 Jordan, 1907, p. 299.

1906 M r . Albert Vierra Sr., Personal conmu- nication.

1906 Evening SentineZ, 1906~ .

1906 SaZinas Daily Indez, 1906e, p. 2.

At Moss Landing, near Sa l inas , t he r e were great horizontal disturbances of the sandy ground; t he o f f i c e of t he s t a t i on agent being displaced about 15 f e e t r e l a t i v e t o the adjoining fence.

The fill leading up t o the b r i dgec ros s ing t he mouth o f the Salinas r i ve r a t Moss Landing has been sha t te red and w i l l have t o be r e b u i l t . This f i l l and t he flood ga te there was put i n about twenty years ago and i t s reconstruction w i l l e n t a i l a grea t expense.

Authors suwnary of notes taken during an interview with Mr. Albert T. Vierra, Sr. , o f Moss Landing, Oec. 3, 1974. Mr. Vierra was 12 yeam o l d - a t the time of the earthquake. Two areas between Monterey Bay and the Sa l inas River were extensively cracked and sh i f t ed many f ee t eastward i n to t he r i ve r . (In 1906, t he Sa l inas River joined with the Pajaro River about 1 mile (1.6 km) north o f Moss Landing and then flowed northwestward i n to Monterey Bay.) The f i r s t area extended from Mass Landing t o approximately t he t i d e gate on the Old Sa l inas River. The second area i s s t i l l expressed as a proman- tory i n to Bennett Slough near the t i d e gate o f f J e t t y Road north of Moss Landing. Many la rge pieces of blue mud were extruded up through some f i s su r e s . The ground ea s t of the Sa l inas River was l i t t l e disturbed. The outer p a r t of t he p i e r , which extended i n to Monterey Bay, brake o f f and sh i f t ed several f e e t ou t t o sea. The p i e r w a s constructed on p i l i ngs over 100 f t (30 m) deep. The present roadway across t he Old Sa l inas River i s constructed on the old narrow gage r a i l r oad bridge which was damaged i n the 1906 shock (f ig. l a ) .

David C. Vierra of Mass Landing repor ts t ha t * * * [at Moss Land- ing] the f i l l s a t the bridge on the county road have f a l l e n i n . A great change has been made i n the dam and mast of t he o ld land in t he slough has sunk and new land r i s en i n i t s place.

At Moss Landing t he r e s u l t s of t he quake were t he most severe i n t h i s immediate vecinity. r * * The bridges were torn up and t he r a i l s o f t he narrow gage road were twisted i n to a l l conceivable shapes where not broken a l toge ther . The wharf was broken off and p i l e s c a s t upon the beach. The grormd along the beach sank several f e e t i n places an (sic) again i n o ther places f i ssures two and three f e e t wide and severa l hundred f e e t long were r en t i n the earth. The roads were cracked fo r miles around. IVhere there were sand dunes a few days ago, now there are deep holes trith water bubbling through them, i n f a c t , water bubbles f o r t h from a l l the cracks and f i ssures . The loss of property a t t he landing w i l l probably reach $10,000.


TABLE 5.Speeif ic descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference t i on "re ure ra- earth- No. No. type cy quake

Quotation

20 I C 1906 Lawson and others, North of Moss Landing the ground s e t t l e d near ly 2 f e e t i n places, 1908, as shown by marks on railway p i l e s a t several slough crossings p. 293. and by t he sagging of t he t rack below grade l i ne i n several o ther

places. The s t r e t c h of narrow-gage t rack p a r a l l e l t o t he coast has been disturbed for near ly i ts whole length; i n same places

4 it i s wavy, i n o thers the e n t i r e roadbed has sh i f ted .

A 1906 Mr. Hans Struve, Author's s m a r y o f notes taken during an interview with Mr. Hans 1974, Struve of Moss Landing, Oec. 3, 1974. Mr. Struve was 14 years old a t personal t he time of the earthquake. The marshlands, r iverbanks, and some communication. farm land along McClusky slough and along t he Pajaro River near i t s

juncture with t he Sa l inas River north of Moss Landing were extensive- 0 l y cracked. Fresh water came out of some f i s su r e s . The bottom of + t h e Pajaro River came up a t a point j u s t nor th of i t s juncture with

t he Sa l inas River causing the Pajaro t o change course and empty i n t o Monterey Bay near t he present mouth o f t he r i ve r .

21 C 1906 Lawson and others, At one point about 5 miles south o f IVatsonville, where t he r a i l r oad 1908, t rack i s only about 200 yards from the beach, a s t r e t ch 100 yards

Or p. 293. long running northwesterly had sh i f t ed a maximum of 12 f e e t t o t he northeast . Fences, telephone poles, and t rack a l l moved together. The sand-dunes facing the bcach d i r e c t l y opposite t he place where t h i s movement occurred look as i f they had been s t ruck by a s i ng l e large wave.

A 1906 M r . J a r v i s hlcGowan, Author's summary of notes taken during an interview with Mr. Jorvis 1973, McGowan, Sr., of Montercy County Ju ly 27, 1973. Mr. McGowan was personal 5 years o ld a t t he time of the 1906 earthquake. On t he day of t he communication. earthquake Mr. McGowan made an inspection t ou r with h i s f a t he r of

the family ranch and o ther nearby s i t e s o f earthquake damage. The McGovan ranch is on a t r a c t of land between t he Pajaro r i v e r and a l i n e o f b lu f f s , 0.7 m i (1.1 km) south of t he r i ve r . The ranch boundaries are 0.9 m i (1.4 km) and 1.2 m i (1.9 km) west of Highway 1. The most severe damage noted by h e . McGowan was t o the narrow gage

r a i l r oad t h a t formerly ran along the south bank of the Pajaro r i v e r where the flood cont ro l dike i s now located. The approximately 4 f t (1.2 m) high embankment was thrown i n t o waves and sh i f t ed l a t e r a l l y a t many locations. These e f f e c t s occurred from Watsonville west t o near t he lnouth of the Pajaro r i ve r . The disturbance t o t he r a i l r oad was much more severe than t o a fence which pa r a l l e l ed the t racks about 16 f t (5 m) t o the south. At some locations t he r a i l - road grade was sh i f t ed away from the fence toward the r iver ; a t o ther locations t he grade appeared t o have sh i f t ed toward the fence. A 25-acre apple orchard on t he McGowan ranch immediately south of t he r a i l r oad was g rea t l y disturbed. Every row of t r e e s i n t he orchard was thrown out of l i n e . In some areas t he t r e e s were pushed toge ther , i n others they were pulled apar t . The orchard was so badly disarranged t h a t i t had t o be taken out.

Picket fences were used i n 1906 t o separa te f i e l d s and ranches. Damage t o north-south trending fences was grea ter than t o east-west t rending fences. Damage a lso at tenuated with d is tance from the r i ve r , f o r example the fence along Trafton road which runs along t he base of t he b lu f f s was damaged very l i t t l e . Typical damage was a l a t e r a l displacement a t some point along north-south fence l i ne s with the northern segment being s h i f t e d r e l a t i v e l y westward, commonly about 3 f t (0.9 m). In some places t he fences were pulled apar t and broken, i n o thers they were deformed i n gent le curves. There d id not appear t o be any pa r t i cu l a r pa t t e rn t o the fence disruptions nor were a l l north-south fences a f fec ted .

TABLES E-9 83

TABLE 5 .Spec i f i c descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Pa i l - Accu- Year of Refcrcncc Quotation t i o n ure ure ra- earth- No. No. type cy quake

Some f i s su r e s were found i n t he f i e l d s but these were not major disturbances. An employee a t t he ranch who was on the bluff a t the

0 time of t he earthquake reported t ha t cracks opened and closed causing water t o spur t several f e e t i n t o the a i r . (Free ground water i n tha t area was encountered a t about a 4 f t (1.3 m) depth i n 1906.) Circular o r oblong zones of subsidence a l so disturbed t he f i e l d s a t sevaral

X locations. In those areas t he ground sank as much as 1.5 f t (0.5 ill).

Some open cracks were found along the top of t he b lu f f s , but no land- s l i d e s were d i r ec t l y t r iggered by the earthquake. However, during the following winter, a period of above normal r a i n f a l l , a number of lands l ides occurred including one t h a t car r ied t he McGowan home from a location near the top of t he bluffs t o a location pa r t way down the slope. (The home was l a t e r moved t o i t s present location a t t he base o f the bluffs .)

A 1906 Lawson and others, I n t he Pajaro Valley, on the McGovan ranch, a t a bend of the r i ve r , n 1908, an acre o r mare of orchard has sunk about 2 f e e t . p. 293.

23 C 1906 Lairson and o thers , Cracks [between Watsonvilie and t he ocean] appear again along the n 1908, Pajaro River and the railway t r a ck has sunk in several places. P. 294.

24 B 1906 Lawson and others, The s ide rods of t he narrow-gage bridge 1 mile south of Watsonville * 1908, are buckled as by a compressive force, and the roadbed a t both I p. 294. approaches has s e t t l e d a t l e a s t 2 inches.

1906 Lawson and o thers 1908, p. 292, p l a t e 116A.


1906 Lawson and o thers , 1908, e. 294.

1906 Duryea and o thers , 1907, p. 259.

1906 Duryea and o thers , 1907, p. 312.

A t IVatsonville r * * considerable s e t t l i n g o f the ground took place i n Chinatown on t he southern s i de o f the r i ve r .

I n Chinatown, on t he south s i de o f t he r i v e r , the s e t t l i n g of t he ground was marked.

r r * evidence o f s e t t l i n g i s found a t t he broad-gage railway bridge a t Batsonvil le , the southeast end o f which sank more than a foot . The t r a ck was a lso twisted i n to an S-shape. The concrete foundation under the engine and s tack a t t he power-house a t the northwest end of the bridge s e t t l e d , but the concrete work was l i t t l e hurt .

The Southern Pac i f ic Bridge across t he Pajaro River, a t Watsonville, consist ing o f four 80-ft. wooden spans on p i l e p i e r s , had the second p i e r from the ea s t end moved (up stream) about 3 f t .

The [highway] bridge a t Watsonville was d i s to r t ed i n a s imi la r manner [ t o t he Sa l inas bridge, loc . no. 121 due t o the s h i f t i n g of t he bank deposits .

Supervisor J. L. Mann * * * repor t s t h a t the damage done t o the Monterey s i de o f the Pajaro r i v e r bridge was * * * caused by a sink which extends along the bank of t he r i v e r on t h i s s ide and allows Chinatown t o drop about four f e e t . This sink, o r f i s su r e , followed t he bank a f t h e r i v e r and en t e r s under the approach from t h i s s ide , throwing t he whole bridge out o f l i ne . * * * another f i s s u r e f o l - lowed t he Watsonville s ide of t he r i ve r , but was not so bad as on t h i s s ide .

The d i s t r i c t drained by t h e Pajaro River, between t h e town of Ho l l i s t e r and Monterey Bay, was much disturbed. The r a i l r oad fo r distances up t o a mile was depressed from 4 t o 6 f e e t .


TABLE 5 .Spec i f i e descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t ion ure ure ra- earth- No. No. type cy quake

C 1865 Lawson and o thers , A t Watsonville there was a heavy shock. The ear th opened i n several 0 1908, places (secondary cracks), throwing up water.

p. 448.

A 1906 Salinas DaiZy Indez, The wagon bridge, the Southern Pac i f i c and t he Pajaro Valley r a i l - * 1906a, road [loc. 241 bridges across t he Pajaro r i v e r are rendered impassable. p. 1.

26 C 1906 Snn Jose M e r c u y , Between Endicotts [ s ic ] and Watsonville the road bed i s s a i d t o have M 1906a, sunk from two t o f i f t e en f ee t .

p. 8.

B 1906 Euening SentineZ, IVATSONVILLE. One thousand f e e t o f S.P. Co.'s t rack between Laguna r[ 1906c, and E l l i c o t t sank from 5 t o 15 f ee t .

p. 6. A considerable area o f ground o f J . P. Thompson's property has been covered with water.

+ The t racks of the Southern Pac i f i c Co. i n a l l d i rec t ions are widen- ing [s ic ] l i k e snake tracks.

C 1906 Evening SentineZ, Between E l l i c o t t s and Watsonville t he roadbed i s s a id t o have sunk 1906d, from two t o f i f t e e n fee t . p. 8.

27 15 C 1906 Lawson and others, Between Pajaro and Vega t he ground cracked along the 2 t o 6 foot 16 1908, b luf f , marking the o ld r i v e r bank on t he south s ide of the present

0 p. 294, channel, and t he s ide toward t he r i v e r has s e t t l e d several f e e t . p l a t e 1418, This i s well shown i n p l a t e 1418. This displacement has caused

0 p l a t e 1438. numerous sand c r a t e r l e t s and p i t s (p la te 1438); t he l a rge s t p i t noted being oval i n shape, 6 by 20 f e e t i n diameter, and 4 f ee t deep.

C 1954 Coffman, 0 1973,

p. 175.

1954. ApriZ 25. East aflVatsonvil le . * ground cracked, and loose ear th s l i d onto t he road.

28 C 1906 Lawson and o thers , Northeast of Vega the movement seems t o have died out , the l a s t 1908, evidence found being mud caps on some o ld p i l e s i n the channel o f

x p. 294. the stream, showing a set t lement of the ground amunt ing t o 8 inches. Between Vega and Chittenden no evidence of movement o f the river-bed could be found.

1953. DecemberlG. Watsonville. * * Boulders were s t r e w on t he road some 5 miles west of Chittenden Junction.

29 X B 1906 Lawson and others, The track a t the southern end o f the Pajaro bridge sank from 2 t o 1908, 4 fee t for a distance o f 150 yards, and between Chittenden and the p. 279. bridge the t rack was bent i n an S-shaped curve i n several places.

The concrete p i e r s of the bridge were cracked, and the grani te cappings sh i f t ed as before noticed. (See p l a t e 658 and f ig . 43.) [namage t o bridge p i e r s most l i k e l y was caused by f a u l t movement.]

C 1890 Coffman, I 1973,

p. 159.

C 1890 Bailey, 1966, p. 361

1890. April. 24. Monterey Bay region. * * * centered near Chittenden r r r . The r a i l r oad was damaged through s e t t l i n g of ground and displacement of a bridge.

On April 24, 1890, a s t rong earthquake damaged Watsonville, Hol l i s te r , and Gilroy. Mr . Joe A"&, who wis a young boy l iv ing i n t he San Andreas rift va l ley i n the nearby Chittenden Pass area a t t he time of t h a t earthquake, was interviewed i n 1963 by Olaf P. Jenkins and [Gordon B . l Oakeshott. h r a r c l ea r l y remembered eround " breakage, which caused Anzar Lake t o drain, and landslides, which closed t he r a i l r oad and highway where t he f a u l t t r a ce crosses Chittenden Pass. He judged t he motion t o be stronger ( a t h i s home) than during t he San Francisco earthquake o f 1906.

TABLES L 9 .- 85 TABLE 5.Specific descriptions of ground failures in the Monterey Bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t i o n ure ure ra- earth- No. No. type cy quake

C 1963 Coffman, 1963. September 14. Vic in i ty of Chittenden and Soda Lake. * 1973, Landslides were reported i n t he Soda Lake and Pajaro Gap areas. p. 181.

30 17 B 1906 Lawson and others, The damage t o t he concrete abutments of the county bridge across the + 1908, Pajaro River i s due t o t h i s crowding i n of the a l l uv i a l banks of t he p. 111. stream.

Lawson and others, 1908, p. 388, p l a t e 126A.

Coffman, 1973, p. 179.

Lawsan and others, 1908, p. 279.


Holden, 1898, p. 150.

2963. September 14. Vic in i ty of Chittenden and Soda Lake. * * * Bridge footings of a highway bridge across t h e Pajaro River were damaged s l i gh t l y .

Several cracks a foot o r l e s s i n width show on the r idge, but the f a u l t seems t o s e t off about 100 yards t o t he northeast and t o cons is t of e a s t and west cracks, having loosened t he whole slope fo r near ly a mile northward o f Chittenden, causing great landslides.

Inland from the coast there were numerous earth-avalanches caused by t he earthquake on the walls of s teep canyons. One of the most noteworthy of these was on t he north s i de of a shor t but deep canyon west of Chittenden and c lose t o t he l i ne of t he f au l t . (P la te 126A.) The rocks composing t he s ide of t he canyon are t he bitwninou5 shales of t he Monterey s e r i e s . The slope r i s e s very s teeply fo r about 500 fee t and was qu i t e dry before t he earthquake, a l t ho it was covered with spring vegetation. Areas o f bare rock appeared t h r u t h i s vege- t a t i on . A t t h e time of the shock several earth-avalanches were s t a r t ed , and these s l i d suddenly down the slope, pa r t of t he material f i l l i n g t he bottom o f t he canyon and pa r t remaining on t he l e s s steep lower port ions o f the slope. The l a rge r masses were broken o f f up near the brink of t he canyon. There was apparently l i t t l e o r no r o t a t i on of the s l i d ing mass. The r e s u l t was t o gorge completely the lower pa r t of the canyon with rack dgbris , t o widen t he upper par t of the canyon, and t o expose extensive surfaces o f unweathered rock.

1954. August 12. East of Watsanville. Rockslides were reported on a road near Logan.

1959. k c h 2, Near Gilroy. * * * Minor ea r t h s l i de occurred on Chittenden Pass Road ea s t of lvatsonville, and boulders f e l l on Hecker Pass Highway between Gilray and Watsanville Lloc. 471.

There i s much su l fur , o i l , gas, and water i n t he h i l l s here [v ic in i ty of Chittenden]. A marked increase was noted i n the flow of o i l and water, and more gas and su l fu r became associated with them.

The disturbance af fec ted t he banks of the Pajaro River from Cl~it tenden t o Sargent, causing a cracking and sloughing of the banks i n to the stream but not a s e t t l i n g o f t he stream bed. The San Benito River was s imi la r ly shaken f o r about 3 miles up from i t s junction with the Pajaro. Cracks are a l so noticeable a l l along the Riverside road wherever it runs close t o t he r i v e r bank.

Near Chittenden the banks are caved in .

1890 * * * April 24 between Pajaro and Sargents. I t is reported t h a t the [rai lroad] t r a ck was moved a foot out of l ine , and t h a t the ground s e t t l e d s i x inches i n places. The bridge, f i f t y f e e t high, i s impassable a t bath ends, t he r a i l s being pulled a foot apar t .


TABLE 5 , S p e c i f i c descriptions of ground failures in the Monterey Bay counties region-Continued

-

Goca- Fig- Fa i l - Accu- Year of Reference Quotation t i on "re ure ra- earth- No. No. type cy quake

C 1885 Coffman, 1885. March 30. * * * Cracks occurred i n so f t banks o f t he Pajara 1973, and Benito Rivers. p. 159.

34 C 1906 Lawson and others, In the h i l l s between San Juan and Natividad the ground i s not cracked, to. 1908, except f o r a few places on h i l l s i d e s where there was some sloughing

p. 295. off .

35 C 1906 Lawson and o thers , In t he lowland t o t he southeast t he r e i s l i t t l e evidence o f t h e 1908, f a u l t , but crossing a t r i g h t angles t he county road running north p. 111. and south about a mile e a s t of San Juan, is a band of small. cracks

X 15 f ee t wide, causing the road t o sink 8 inches and making a marsh o f t he f i e l d beyond.

1800 Townley and Allen, 1939,

1800 October 11 t o October 31. [VIII o r IX. San Juan ~ a u t i s t a . 1 * [ A l l t h e buildings were damaged and cracks appeared i n the ground near t he Pajaro River -- Hutchings' California Magazine, 5, 310.1

1800 Coffman, 1973, p. 155.

1800. October l l f P I . San Juan Bautista. * * r Cracks were observed i n the ground of the rancheria; a deep f i s su r e was reported along t he slope o f the Pajara River.

1906 Lawson and o thers , 1908, p. 288.

One o ld s e t t l e r remembers when the business pa r t o f Ho l l i s t e r was a slough. An a r t e s i an b e l t a l so passes t h r u the town, which may have af fec ted t he i n t ens i t y along i t s path.


There were no changes i n t h e ground a t Ho l l i s t e r save some s l i g h t cracks i n the v i c in i t y ; * r *


Psicine*, tho south o f Tres Pinos, * * t . Water is s a id t o have spouted up i n t he f l a t land along the CSan Benit01 r i v e r , 0.25 mile from the stream.


* a small peak near Santa Ana showed a lands l ide down its steep face, p l a in ly v i s i b l e a t a d is tance o f 6 miles. A huge rock, r o l l i n g down a h i l l i n Santa Ana Valley, crashed t h r u a howe and k i l l e d a man.


The road a t Corra l i tos is s a id t o have been s l i g h t l y cracked, and i n the low h i l l s between Valencia and Corra l i tos a few cracks were found; but t he f a u l t evidently runs f u l l y 0.5 mile e a s t of Corral i tos. The mountain roads ea s t and nor theas t of Corra l i tos were rendered impassable by lands l ides and by bridges being injured.


On t he higher ground between Watsonville and Aptos, t he shock was l i t t l e f e l t . There was no movement along Aptos Creek, both wagon and railway bridges being unaffected.


* * * Capitola * * * . Much ea r t h f e l l from b lu f f s near the t o m , but there was no appreciable e f f ec t on the surf . A t the country bridge across Soquel Creek, t h e ground a t the e a s t abutment shoved inward, cracking t he concrete and buckling a water-pipe.

1906 Lawsan and o thers , 1908, p. 292.

The e a s t abutment o f t he concrete wagon bridge over Soquel Creek cracked ve r t i c a l l y , showing t h a t the s o i l movement extended t h i s f a r up t he creek.

TABLES 5 9 87

TABLE 5 , S p e c i f c descriptions of ground failures in the Monterey Bay counties region-Continued

Laca- Fig- Fa i l - Accu- Year of Reference t i on ure ure ra- earth- No. No. type cy quake

Quotation

43 A 1906 Lawson and o thers , A t the Southern Pac i f i c bridge, crossing the San Lorenro River, 1908, there i s a network of f i s su r e s varying from 2 t o 15 inches i n width, p. 271. running t h ru the sandy s o i l . The d i rec t ion o f t he main f i ssures is

ea s t and west, and they are on the south s ide of the r i v e r , which is x nearest the bay. The ground has s e t t l e d about 10 inches from the

abutments and p i e r s of the bridge. The depth of the f i s su r e s was

0 indeterminable, as they had f i l l e d with sand.

1906 Evening Sentinel, 1906a,

1906 Evening Sentinel, 1906b,

1906 Evening Sentinet, 1906e,




1906 Smta C m z Surf, 1906, p. 5.

There are many cracks i n t he ear th i n various pa r t s of the c i t y [ ~ a n t a Crur], as for instance near the depot, and a t the corner of Front S t . and Soquel Av. Near t he Riverside Hotel the s t r e e t has dropped several inches.

* * r The r a i l r oad embankment extending from Casino [on arcade] t d r i v e r has sunk.

Along the water front there were qu i t e a number o f f r i ek i sh [sic] pranks of the temblor. The ea r t h along the esplanade was opened i n places and l e f t gaping wide.

A t the Riverside Hotel, ground i n the orchard opened and r i v e r bottom sand and water were thrown up upon the surface o f t he ground, t he ear th c los ing again. A s im i l a r occurrence happened a t Watsanville [loc. 251, and well d r i l l e r s say tha t t he s o f t blue s o i l exuded is such as i s found not l e s s than 100 fee t beneath the surface of t he earth.

A t the north end o f t he bridge cmss ing the San Lorenzo River, a t Third S t r ee t , there were 4 f i s su r e s running p r ac t i c a l l y p a r a l l e l and almost due ea s t and west. These f i s su r e s are about 700 yards i n length, and vary i n width from 2 t o 8 inches. They run t h ru an apple orchard and are i n sandy s o i l , the sof tness o f the land near the river-bed being apparently responsible f o r t h e i r presence. The r i v e r a t t h i s p lace runs about eas t .

Along the San Lorenzo River, a t Santa Cruz, t h i s s e t t l i n g ac t ion [as along the Pajaro River] a l so took place fo r a mile o r more upstream from i t s mouth.

In going t h ru t he town of Santa Crue i n the d i rec t ion of Boulder Creek, a f i s s u r e a t t he in te rsec t ion of Bulkhead and River S t r ee t s was noticed. This f i s su r e was about 1.5 inches wide and ran ea s t and west.

[Picture caption] Fissures i n soft mud of r i v e r bank. [See a l so locs . 45 and 46.1


TABLE 6.Speci f ic descriptions of ground failures i n the S u n Francisco Bay counties region

Location number i s assigned t o each reported ground-failure s i t e . Corresponding numbers are found an p l a t e 2. Figure nlrmber r e f e r s t o f igure i n t h i s report showing damage described under "Quotation" column. Failure type is indicated by the following symbols. Corresponding symbols are found on p l a t e 2.

Hi l l s ide landslides including ro t a t i ona l slumps, . . . ... River s t r e t che s with extensively f i ssured flood . . .

block glides, debris avalanches, and m c k f a l l s p la ins ; pa t t e rn indica tes s t r e t che s of r i v e r affected and not width of disturbed zone

0 Streambank landslides including m t a t i o n a l slumps and s o i l f a l l s 0 Sand bo i l s

Lateral spread @ Disturbed wells

I Ground set t lement Absence of ground f a i l u r e noted

Ground cracks not c l e a r l y associated with land- Miscellaneous e f f e c t s s l i de s , l a t e r a l spreads, set t lement o r primary f a u l t movements tD, Arrows showing extent of area af fec ted . Symbol

shows f a i l u r e type

Accuracy with which f a i l u r e s i t e s can be located i s given as follows: A, a s i t e t ha t can be accurately relocated; B; a s i t e t ha t can be relocated t o within a few kilometers and probably could be located more accurately with fu r t he r inveb- t iga t ion; C, a s i t e where t he information is insuf f ic ien t t o allow prec ise location.

P la te numbers i n the "Reference" column r e f e r t o p l a t e s in the o r i g ina l source material .

Santa Crua Mowtnins

Loca- Fig- Fail- Accu- Year of Reference Quotation t i a n ure "re ra- earth- No. No. type cy quake

45 B 1906 Lawson and others, (R. Co1lom.)--Going north from Santa Crus, a small f i s su r e ran north- 1908, west and southeast on t he Boulder Creek road, about 0.75 mile north- p. 271. west of the Cal i forn ia Powder Works. Along t he lower end of t h i s

II road were severa l small and unimportant lands l ides . In general, t h e shock in t h i s region does not seem t o have been as severe as it was f a r t he r north.

46 B 1906 Lawson and others, (G.A. Wring . ) - -me c i t y of Santa CNZ furnishes excellent evidence 1908, of the e f f ec t of s o i l formation on t he i n t ens i t y of t he earthquake

0 p. 271. shock. . * * The San Loreneo River was churned i n to foam, the bmks 0 cracking and s e t t l i n g several inches; and sand, s a id t o have corns

from a depth of 100 f ee t , was forced up i n severa l places. The bed o f the r i v e r is a lso s a id t o have sunk severa l inches, and t he current t o be slower than before. A 6-inch water-main, running ea s t and west across t h e r i v e r a t the covered bridge, was broken a t each end o f the

e bridge and moved 5.5 inches eastward.

0 C 1865 Lawson and others, A t Santa Cruz * * * The lowlands along t he r i v e r opened and spouted 6' 1908, water l i ke geysers. Some wells went dry or were f i l l e d with sand.

p. 448. [See a l so locs . 43 and 44.1

47 C 1947 Coffman, 1947. June 22. * * * Hecker Pass was reported closed by s l i d e s 1973, p. 172.

1959. March 2. Near Gilroy. * * * Minor ea r t h s l i de occurred on Chittenden Pass Road ea s t of Watsonville [ loc. 311, and boulders f e l l on Hecker Pass Highway between Gilroy and Watsanville.

48 B 1906 Lawson and o thers , The Saunders ranch i s 3.5 miles southwest of Madrone, on the 1908, Madrone road. * * * port ions of what appeared t o be qu i t e s o l i d p. 283. and massive rock outcrops were thrown from the s teep h i l l s near the

house.

C 1967 Coffman, 1967. September 28. Rockslides occurred i n t he Morgan H i l l area 1973, p. 183.

TABLES E-9 89

TABLE 6.Specif ic descriptions of ground failures in the San Francisco Bay counties region-Continued

Santa h z Mountains--Continued

Loca- Fig- Fa i l - Aecu- Year of Reference Quotation t i o n "re ure ra- earth- No. No. type cy quake

49 C 1906 Lawson and o thers , Two miles west o f Uvas P.O., and ha l f a mile e a s t of the sumit 2( 1908, in wet places there was a noticeable s e t t l i n g of the ground.

p. 288.

50 B 1906 Lawson and o thers , Near Olive Springs, 12 miles nor th of Santa Cruz, an earth-avalanche 1908, demolished Loma P r i e t a M i l l and k i l l e d several men. p. 389.

B 1906 Lawson and others, A t Santa Crur the inhabitants reported t h a t near Olive Springs, 12 1908, miles north of Santa Cruz, a lands l ide demolished Lorna P r i e t a M i l l p. 271. and k i l l e d 9 men.

B 1906 Lawson and others, * * the [ fau l t ] crack goes i n to Hinkley's Gulch, i n which t he 1908, Loma P r i e t a Mills are s i tua ted , and which are buried under the p. 278. s l i de s .

B 1906 Lawsan and o thers , On t he northern s i de o f Bridge Creek Canyon t he r e are typica l cracks 1908, from 1 t o 8 inches wide, and here a l so occurred a great landslide p. 110. which buried the Loma P r i e t a M i l l .

Jordan, [picture caption] Wreck o f Lorna P r i e t a Sawmill, Hinckley's Gulch, 1907, Santa Crur County. p. %I.

Jordan, [Picture caption] S i t e of Lorna P r i e t a Sawmill, covered t o a depth 1907, of 125 Feet. p. 31.

SaZ$nas DaiZy Indez, Loma P r i e t a Lumber Company's M i l l . The m i l l , boarding house and 1906d. o ther buildings of t he p lan t were s i t ua t ed i n a gulch, and were

ovemhelmed by a port ion of the mountain--1500 f e e t long, 400 f e e t wide and 100 f e e t deep which s l i d down upon them. The m i l l and everything i n the gulch were forced up t he opposite slope of the mountain and there buried t o a depth o f one hundred fee t . Pine and redwood t r e e s 100 f ee t high came down with t he s l i d e and are now standing over the m i l l s i t e as though they had grown there. Nine men were k i l l e d r + * .

SaZims DaiZy Index, LObR PRIETA CO'S LOSS. When the earthquake occurred yesterday 1906b. morning it caused a large mountain o f ear th t o s l i d e i n to the

canyon and completely covering t he new m i l l . Continuing i t s course up t he mountain on the o ther s i de it covered what i s known as t he bunk house and buried ten men, who were asleep a t the time.

Lawson and o thers , The s l i d e s which ob l i t e r a t ed Fern Gulch a t Skyland do not seem t o 1908, have come from the Cfault] crack, but seem t o l i e t o the west o f p. 278. the crack.

Lawson and others, Skyland, Snntn C r i u County * * * Large landslides occurred i n the 1908, neighborhood. p. 278.

Lawson and others, Gulches appear t o have been contracted, as t he bridges crossing 1908, them show tha t they were squeezed. The banks of Burrel l Creek p. 276. appear t o have approached each other, s o t ha t t he creek has become

very much narrowed. Water-pipes were broken and twisted, and f i l l e d with d i r t .

Lawson and others, Here [ridge j u s t west of skyland?] * * great landslides occurred, 1908, and redwoods were snapt o f f o r uprooted. p. 110.


TABLE 6.Specif ic descriptions of groand failures in the San Francisco Bay counties region-Continued

Santa Cruz Mountains--Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t i o n ure ure ra- earth- No. No. type cy quake

55 18 B 1906 Lawson and o thers , A l a rge lands l ide a l so occurred c lose t o Wright S ta t ion , p a r t l y 1908, darning up t he stream. p. 110.

B 1906 Lawson and o thers , Ju s t north o f Wright's S ta t ion , on the west bank of Los Gatos Creek, 1908, there was a lands l ide 0.5 mile wide which had s l i d i n to the creek and

, p. 276. darned it. The top of t h i s s l i d e was near t he S m i t school-house and was close t o the main fau l t - l ine .

B 1906 Lawson and o thers , A l a rge s l i d e close t o Wright S ta t ion p a r t l y dammed the stream. 1908, p. 389.

56 B 1906 Lawson and others, A t F ree ly ' s place, 4 o r 5 miles north o f Morrel l 's , some 15 acres of 1908, woodland have s l i d i n to Los Gatos Creek, making a la rge pond. There p. 278. are many o ther s l i de s i n t he neighborhood and many broken t r e e s .

B 1906 Jordan, 1907, p. 27.

I n t o t h i s [Los Gatos] creek, from the Feely ranch, some ten acres o f land was thrown i n a grea t landslide. At the head of the creek i s t he long tunnel which cu ts under t he saddle, from Wright's t o Laurel.

Landslides were abundant, espec ia l ly i n the Santa Cruz Mountains, where the topography i s more rugged. One s l i d e , a few miles from Wright's S ta t ion , involved e ight t o ten acres of ground.

B 1906 Lawson and o thers , On the ranch of O r . Tevis [presently t he s i t e of Alma College], about 1908, a mile from Alma Sta t ion , where t he land i s r o l l i n g and wooded, the p. 275, ground was f i ssured and t he bottom o f an a r t i f i c i a l lake was upheaved. p l a t e 139C, (P la te 139C, D.) The cracks and f i s su r e s , o f which there are many, p l a t e 1390. run mostly north and south, and vary i n length up t o 100 f ee t , and

i n width from 0.5 inch o r l e s s t o 20 inches. While a good many of t he openings were p a r a l l e l t o the slopes and were caused by the ground s t a r t i n g t o s l i d e , o thers crost t h e roads and could be t raced same d is tance up the banks. A board fence was sp l in te red where it + crest a f i ssure . The upheaval o f the lake was caused by a c los ing together of the s ides , shorn by t he heaving up o f p a r t s o f the r e t a in ing dam a t the lower end of the lake. The r i s e o f t he bottom is roughly 10 f ee t . [Some cracks described above may be f a u l t ruptures.]

58 B 1906 Lawson and o thers , Mr. Carey a l so repor ts another earth-avalanche located on the Pe t ty 1908, ranch, about 4 miles southeast of t he one j u s t described [Deer Creek p. 388. landslide, loc. 741. Here a huge rock mass, which embraces an a rea

o f about 12 acres a t t he headwaters of Cauley Gulch, broke away from a ledge and dropt , leaving a ve r t i c a l scarp o f 40 f e e t o r more. The rock mass i n t h i s case was not sha t te red . It p r ac t i c a l l y main- ta ined its in t eg r i t y . The narrow gulch below was unfavorable f o r f ree downward movement. A s t h e block readjusted i t s e l f , i t s upper surface became near ly l eve l , but was lower a t t he foot of the scarp than a t i t s ou ter edge, thus indica t ing t ha t i t had suffered ro ta t ion .


The whole r idge vest o f the reservoi rs [about 2 miles south o f Congress Springs] was severely shaken, however, f o r cracks 4 o r 5 inches wide opened near Grizzly Rock and several l a rge s l i d e s occurred i n its neighborhood [loc. 741. One water-pipe running north and south on the Beatty p lace was broken, while one trending ea s t and west was unhurt. No cracks were found crossing t he r idge between Grizzly Rock and White Rack. The cracks were next found on the road about a mile e a s t o f B.M. 2135 o f the U.S. Geological Survey, but they do not show i n t he vineyard t o t he southeast .

TABLES 5 9 91

TABLE 6 . S p e c i f i c descriptions of ground failures in the Sun Francisco Bay counties region-Continued

Santn Cruz Mowtains--Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t i an "re ure ra- earth- No. No. type cy quake

-

60 C 1865 Holden, 0

1865, October 8. A t Mountain Charley's, on t he Santa Cruz road, the 1898, ear th opened i n several places, and steam and water were thrown up p. 67. through the cracks.

1865 Coffman, 1973, p. 157. .





1906 Lawson and others, 1908, p. 269, map 22.


1865. October 8. A t Mountain Charley's, t h e ear th opened and boulders obstructed the road.

Great s l i d e s on both s ides of Aptas Creek have almost made a valley of the canyon f o r f u l l y 0.75 mile. Following across the r idges and canyons, the discontinuous l i ne of s l i d e s and s inks i n upland marshy places marks t he course of the f au l t - l i ne down i n t o t he lowland.

On the westeln slope of the r idge j u s t west of Skyland, several earth- avalanches were caused by the shock; and great s l i d e s o f a s imi la r character occurred on both s ides of Aptos Creek f o r 0.75 mile. Besides these, there were many smaller earth-avalanches i n many p a r t s o f t he Santa Cruz Mountains which can not be enumerated.

About four mites south of Wright S t a t i on * * * The ridge on which we camped was f u l l of cracks, ranging up t o 2 and 3 f e e t i n width, and in length from a few rods t o 0.25 mile, a l l t rending west of north t o northwest. * t The canyon south of us was f i l l e d with landslides. In t h i s canyon the s t r a t i f i c a t i o n of the rocks i s p l a in ly shown. The s t r i k e i s northwest-southeast and t he d ip i s almost ve r t i c a l . The cracks coincide i n d i rec t ion with the s t r i k e of t he s t r a t a . Cold water was flaioing from some of the cracks. I obtained a small b o t t l e of crude o i l from M r . Sutton, which he s a id was d i p t up fmm the ground an h i s neighbor's ranch, several hundred gallons of o i l having run out of the ground since the earthquake, where there had been no s ign of o i l before.

Landslides and cracks are reported between Scot t Valley and Felton, and the dam across a small lake was cracked.

A t Ben Lomond no f i s su r e s nor o ther such evidences of the earthquake were t o be seen. Inquiry showed t h i s condition t o continue i n the c o w t r y about the town.

At the dam an Big Creek ( a t 48, map No. 22), no harm had been done * * . A ha l f mile from t h i s point cracks caused by s l i d e s were noticed on a very steep bank.

A long, narrow landslide above a house 0.75 mile northeast of t he mouth o f Waddell Creek had landed against t he end of the house, taking out a s t r i p o f ear th below a spring and causing a good supply o f water t o i ssue forth. This s l i d e appeared t o be p a r t l y due t o the large amount o f water present .

67 B 1906 Lawson and others, Half a mile southeast of where the main road crosses Finney Creek, 1908, a ledge of shale had been knocked i n t o the gulch. The la rges t p iece p. 274. which f e l l had an unbroken surface o f about 4 square f e e t . The

almost horizontal edges o f sha le beds near a house a t t h i s point were knocked down.


TABLE 6.Specifie descriptions of ground failures in the San Francisco Bay counties region-Continued

Sonta C m z Mimtains--Continued

Loca- Fig- Fail- Accu- Year of Reference t i on ufe "re ra- earth- No. No. type cy quake

Quotation

A t t h e north end of Ben Lomond Mountain, a s l i d e car r ied t r e e s and brush down t o the creek.


(H. W. Bell.)--* * * Near a deserted m i l l a t the north-end of Ben Lomond hlountain, a small landslide had car r ied t r e e s and brush down t o the creek, and t a l l t r e e s had f a l l e n along the road.

L a s o n and o thers , 1908, p. 269.

[Near Bloom's Mill on Waddel creek] A s teep bank beside t he road showed small cracks, which could apparently have been e a s i l y made i n the loose s o i l .

A small e a r t h s l i de had s t a r t e d ( a t 45, map No. 22), and a crack, perhaps due t o the same s l i d e , was noticed.

Law~on and others, 1908, p. 268, map 22.

Mr. Bloom, owner o f a sawmill a t the edge of t he Big Basin, repor t s t h a t the shock was l e s s severe i n the Big Basin region than a t Boulder Creek; t ha t there were no landslides on the road between the two places; and t h a t , tho he had been nearly t o the summit on t he day of the earthquake, he had seen only one crack where the ear th had s t a r t e d t o s l i de .


Lairson and others, 1908, p. 268.

Near the junction o f the f i r s t road leading from Boulder Creek i n t o the Big Basin, an o ld lands l ide which covered about 2 o r 3 acres, da t ing back t o the previous winter , had been widened by t h e shock and i t s d i rec t ion had changed.


A t Boulder Creek a la rge port ion of the s o i l was shaken loose from an abrupt h i l l 150 f ee t high, and f e l l t o the leve l of the creek, carrying t r e e s with it.


(R. Co1lam.)--At Boulder Creek, on the e a s t s i de of the stream, a small h i l l o f about 150 f e e t elevation r i s e s r a t he r abruptly.

Near the top [of the h i l l ] , a la rge port ion of the surface so i l had been shaken loose, and had s l i d t o the leve l of the creek, carrying t r e e s with i t .

The ear th opened during the great shock i n the Bear Creek road, f i ve miles above Boulder Creek t o a depth of two and one-half feet . Fmm the f i s su r e immense quan t i t i e s o f inky black water i s pouring.

S u d y Mercuy and Kerald, 1906..

74 A 1906 Lawson and o thers , On Deer Creek, i n the Santa Crur Mountains, an extensive earth- rn 1908, avalanche s t a r t e d near Grizzly Rock and moved westward down a s teep ,

p. 388, narrow canyon fo r about 0.25 mile. (Plates 1240 and 125A.) I t then 19 p l a t e 1240, changed its course t h ru an angle of about 60' as it entered a wider

p l a t e 125A. canyon of lower grade, and following t h i s f o r another 0.25 mile, f i na l l y s t op t a t the Hoffman" Shingle Mill, which was wrecked. A f i ne growth of redwood, some 200 fee t i n he ight , iras mowed down, and covered t o the extent of 10 acres or mare with hom 30 t o 60 f e e t of debris . The t r e e s were from 3 t o 10 f ee t i n diameter. The main canyon was f i l l e d w i t h ear th and rack fo r an average width of 80 yards and a length o f 400 yards. The e n t i r e area of t he s l i d e was about 25 acres. The difference i n a l t i t u d e between t he point where the s l i d e s t a r t e d and the sh ingle m i l l , where it s top t , i s 500 f ee t . According t o Mr. G. A. Waxing, the s l i d e material has a depth of 300 f ee t and is composed of s o i l , clay, and shale. M r . E. P. Carey, who examined and photographed t h i s i n t e r e s t i ng earth-avalanche, s t a t e s t ha t it or ig ina ted i n rock t h a t bmke away i n pieces from the s teeply

TABLES 5-9

TABLE 6,Speeif ic descriptions of ground failures in the Sun Francisco Bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t i on ure ure ra- earth- No. No. type cy quake

inclined slope a t the head of the gulch, leaving a large thea ter - l ike space, the bare, l ight-colored rock walls of which were in sharp cont ras t with the surrounding green vegetation. The movement was f a s t e r i n the center o r deepest p a r t of the gorge than on the margins. The rack was i n general p i l ed up higher along both s ides than i n the center , and many pieces became entangled i n the standing o r uprooted t rees . A steep-walled t r i bu t a ry t o the southeast o f the main gulch supplied mck material t o the main avlanche, and t he 2 streams joined much as confluent g lac ie rs do. The material involved i n the avalanche showed every gradation fmm powder t o angular pieces 30 f e e t o r more i n diameter. The surface was uneven throughout. Near t he m i l l a man was k i l l e d by a t r e e t ha t f e l l as t he avalanche was advancing.

A 1906 Lawson and a thers , On Deer Creek a l a rge lands l ide s t a r t e d from near Grizzly Rock and 1908, s l i d westward, but changed its d i r ec t i on 60' or more f a r t he r down p. 267. toward the creek. The m i l l i n the creek bottom below the s l i d e iras

l l a r t ly buried. and one man was k i l l ed . I t i s 500 f ee t from the mill in thk gulch t o the tap , a t the point where t he s l i d e s t a r t ed . The s l i d e covered about 25 acres o f ground, and destroyed a l o t of v i rg in timber from 3 t o 10 f e e t i n diameter. The s l i d e material , which i s 300 fee t deep, i s composed of s o i l , clay, and shale.

IJ A 1906 Lawson and others, A small landslide had moved across the road [a t 44, map No. ZZ), 1908, which 20 men spent one and a ha l f days c lear ing away. p. 268.

Lawsan and others, 1908, p. 389.

A s imi la r [to loc. 851 earth-avalanche was caused by the earthquake on the ranch of Judge Welch, not f a r from Long Bridge and within 2 miles of Saratoga. Mr. Herre repor t s t h a t here the s o i l on t he northwest s ide of a small creek coming down from the Castle Rock Ridge, was shaken down f o r perhaps 0.5 mile, tho not continuously. In places the s l i d e material f i l l e d up t he creek-bed and t o t a l l y changed the contour. I t destroyed t he road t o t he ranches f a r t he r up the canyon, and wrecked some bridges. Along the upper p a r t of the area af fec ted , a vineyard was destroyed; while f a r t he r down the canyon a heavy fo r e s t growth, cons is t ing mostly of rediraad, oak, a lder , and l au r e l , was obl i te ra ted . This s l i d e l i e s i n the path of the San h d r e a s f au l t .

77 C 1906 Lawson and others, Congress Springs * * r The car t racks on the curve near t he path 0 1908, t o the spring had been thrown aver toward the bank fo r about 20 f e e t

p. 262. of the curve, a 4-inch displacement resu l t ing .

78 C 1906 Lawson and others, Following the Stevens Creek road on down toward Congress Springs, @ 1908, severa l landslides were noted, mostly small ones due t o caving i n

p. 109. of the banks of the creek. J u s t west of the springs the road was badly broken, twisted, and shoved up i n places, t he downthmw being f i r s t on one s i de and then on t he other. In some places along the bank the west s ide projected 2 inches f a r t he r than the other, while t he fence showed an of fse t of 2 f e e t . The la rge stone bridge across t he creek appeared i n t a c t , but west o f i t a large patch of ground had S l i p t down 2 fee t .

79 B 1906 Lawson and others, On the Azule Springs road * * * Near the place where f ive roads fork, 1908, one mile north o f Azule Springs on the road running southeast from p. 262. the forks, there was a &foot dmp on t he road caused by a sec t ion

sinking i n a so l i d piece on a long s lope , without much disturbance i n i ts v i c in i t y .

C 1906 Jordan, [picture caption] Ri f t Across Road near Azul Springs, Santa Clara 1907, County.


TABLE 6.Specif ie descriptions of ground failures in the San Francisco Bay counties region-Continued


--

Loca- Fig- Fail- Accu- Year of Reference t ion ure ure ra- earth- No. No. type cy quake

Quotation

~

80 C 1906 Lawson and o thers , On the Stevens Creek road, j u s t a f t e r leaving the Saratoga road r * * 1908, a crack 2 inches wide shoired a downthmw of 2 inches on t he west p. 262. s ide . * * * a t the next turn, 0.5 mile southeast o f Stevens Creek

* a la rge area of ground, extending fo r 150 f ee t , had been torn 0 up i n a d i rec t ion o f N. 3' W., and a s l i d e formed which almost blocked

the road.

B 1906 Lawson and others, A t the southeast corner o f the same grant b a n Antonio] * * * . 1908, The road i n front of the house [Se l l inger ' s ] was cracked, but pmbably o. 261. on account of the steeo slooe below the road. South of the iiause. .

across Stevens Creek, ;hereAwas a landslide 100 f e e t i n width on t he steep face of a b luf f .

B 1906 Lawson and others, Only one more e f fec t of the shock was noted i n t h i s v i c in i t y ; namely, 1908, the bridge over Stevens Creek, on t he road running due ea s t and west

0 p. 262. fmm West Side, was rendered unsafe f o r horses by being shoved a foot out o f place.

A 1906 Lawson and others, On the northeast s i de o f the creek, 0.25 mile south of t he place 1908, where a mad turns northeast from the Stevens Creek road t o go up p. 262. Monte Bello r idge , there was a la rge lands l ide about 0.5 mile long

and te r raced from the top o f t he mountain.

82 @ C 1906 Lawson and o thers , There were numerous s l i d e s along Stevens Creek, due ch ief ly t o the 1908, caving of the creek banks. p. 389.

C 1906 Lawson and others, The shor t road which runs northwest along Stevens Creek fo r a couple 1908, of miles beyond t he junction with t he cross-road which connects with p. 262. the Monte Bello r idge showed an exposure of serpentine with cracks

running along it N. 3° W. The cracks a t the widest po in t measured about one foot . In t he serpentine area the ground was badly broken up, and i n one place it was covered with 3 f e e t of water. (Observa- t i o n made April 22-23.) [Some o f these cracks may have been f a u l t ruptures.] Following the road northwest beyond t he terminus shown

@ i n t he map, many cracks were seen, due t o b ig landslides. Fallen t r e e s have rendered the road impassable; boulders and dead t r e e s still f e l l occasionally; even while the observer was there a la rge t r e e f e l l no t 10 f ee t from him, loosening rocks and s o i l . J u s t south of t he two houses near the southern end of t he cross-road

leading toward t he Monte Bello road fmm the Stevens Creek road, a break ran due ea s t and west; it was 2 inches wide with a downthrow of 0.25 inch on the west s ide . * * * Another crack 4 inches wide was found i n the road above t he house.

83 C 1906 Lawson and others, (F. Lane.)--Along t he r idge road southwest of Stevens Creek, sepa- 1908, a c i n g Santa Clara and Sanra Cruz Coult ies, there were some cracks p. 264. due t o landslides. Sandstone blocks, some of them 6 f ee t i n diame-

t e r , had r o l l e d down the h i l l s toward t he creek.

C 1906 Lawson and others, Along the r idge road southwest o f Stevens Creek, sandstone blocks, 1908, some of them 6 f ee t i n diameter, r o l l e d down the h i l l s toward t he p. 389. creek.

84 C 1906 Lawson and o thers , Mr. Herre fu r t he r repor t s a la rge s l i d e on t he Mindego Ranch, 20 1908, miles southwest of Palo Alto. Here, on the nor th s i de of Alpine p. 389. Creek, a t r a c t of some 50 acres sank a t the time of the earthquake,

with l i t t l e o r no amaren t forward movement. The t r a c t s l o ~ e d t o the south and wes t , "kd formed p a r t of a grea t , open h i l l pasture, with t r e e s and underbrush about the lower or creek s ide . The creek- bed i t s e l f is f i l l e d with a growth o f Douglas spruces and other trees. The land, which before the earthquake was s teeply inclined,

TABLES 6 9


Loca- Pig- Fa i l - Accu- Year of Reference Quotation t i on "re ure ra- earth- No. No. type cy quake

is now comparatively leve l , the eas te rn and northern pa r t having sunk perhaps 100 f ee t , while t h a t on the west has sunk but 10 o r 15 fee t . The surface of the sunken t r a c t was g rea t l y seamed and cracked, and pa r t of i t was flooded, owing t o the springs uncovered; but otherwise it was unchanged i n appearance. There was no p i l i ng up of ear th , nor s l i d ing of one port ion over another. A fence c ros t t hc t r a c t , and the posts on it sank so tha t but a few inches protruded above the surface; while some Douglas spruces a l so sank several f e e t i n t o the ear th . A number of c a t t l e were on the land a t the time of the earthquake, but were uninjured. I t was a work of great d i f f i c u l t y t o remove them, block and tackle being necessary. The creek-bed was apparently not affected, nor were t he t r e e s i n it disturbed. There was no apparent movement of the ear th i n t o the canyon, but the whole mass seems simply t o have been dropt from a s teep slope t o a near ly uniform leve l , surrounded by t he high, blank, almost perpendicular walls o f ear th and rock from which it had been sundered.

85 0 C 1906 Lawsan and o thers , * * * on the ranch of Andrew Stengel, an earth-avalanche is reported 1908, * r on a small t r i bu t a ry o f Alpine Creek, and about 4 miles south- p. 388. west of the San Andreas f a u l t a t the point where the l a t t e r crosses

Black Mountain i n t o the head of Stevens Creek Canyon. The creek here i s i n a narrow, steep-walled canyon i n the bituminous sha le of the Monterey s e r i e s . The s o i l on t he canyon s i de was very shallow, and a t the time o f t he earthquake it was shaken dolm i n t o the bottom of t he canyon, leaving t he walls absolutely bare i n places f o r a hundred yards a t a s t r e t ch . The s l i d e extends f o r 0.25 mile on both s ides of t h e canyon.

86 B 1906 Lawson and o thers , Four miles from the t o m o f Pescadero, on t he ea s t s i de of a bridge 1908, over Pescadero Crcck, the ground had sunk 2 inches and the aperture p. 273. f i l l e d by the land s l i d ing . A mile nearer t he town, the road had

dropt 5 fee t , but had been f i l l e d by a b ig s l i de . A house a t t h i s point was qu i t e i n t a c t , but t he chicken-house near it was car r ied

[;1 down and p a r t l y buried by the landslide. On Eues Creek, near i t s junction with Pescadero Creek, a h i l l s i d e had s t a r t e d t o s l i d e and apparently needed only t o become rain-soaked t o continue the sl ipping.

87 [;1 B 1906 Lawson and o thers , A s n a l l l ands l ip , 0.25 mile up t he ea s t s i de of the shor t creek 1908, which flows i n t o Gaeos, j u s t west of the fork of the road which p. 273. continues northwestward t o L i t t l e Butano Creek, showed a 2-foot

ve r t i c a l displacement a t the top, and the land had shoved i n to the road below. This s l i d e measured 150 f e e t from i ts top t o t he road, and i t s width a t the road was 100 f ee t .

88 C 1906 Lawsan and others, Near a house on the leve l creek bed of L i t t l e Butano Creek, 4 cracks 1908, averaging 3 inches i n width and about 20 f ee t i n length ran N. 33' p. 273. E. The only crack noticed along t he t r a i l tdwsrd the coast was 1

mile northwest o f the p lace where L i t t l e Butano Creek turns from southwest t o northwest, and was about t he same length, but ran N. 3- W.

89 C 1906 Lawson and others, (G.A. Warins.)--On Butano Creek there were s l i g h t cracks i n the road, a 1908, and the streams were muddy. + * * the banks beside the road showed p. 273. t races o f caving, there were only s l i g h t cracks, the longest one

being.in the middle o f the road above t he creek, running N. 67' E. f a r a d is tance o f about 50 f ee t .


TABLE 6.Specif ic descriptions of ground failures in the Son Francisco Bay counties region-Continued


Loca- Fig- Fa i l - Accu- Year of Reference Quotation t ion ure ure ra- earth- No. No. type cy quake

90 C 1906 Lawson and others, A l-inch crack a t the f i r s t fork o f the road a mile from the town 1908, of Pescadero extended north and south f o r about 50 f ee t , * * * p. 273. and water oozed out of leve l ground near by.

91 C 1906 Lawson and others, In the t o m of Pescadera * . Cracks were v i s i b l e i n the s t r e e t s . 1908, * * Cracks in t he road a l so appeared, and dust spurted up. r r * p. 272. Going eastward from Pescadero, a small crack 30 f e e t long, with an

eas t and west s t r i k e , was observed. In an orchard near by there were several cracks, the widest one measuring 8 inches, with a ve r t i c a l displacement o f 1 foot.

Carey, 1906, p. 297.


Lawson and o thers , 1908, p. 266.

Sen Jose Mercuy, 19062..

Lawson and others, 1908, p. 266, map 22.

Near Pescadem natura l i l luminating gas is reported t o have escaped from f i s su r e s made i n t he gmund, but during subsequent shocks the amount t ha t escaped s t e ad i l y decreased.

1868, October 21, Santa Cruz Mountains, near Pescadero. * * l a rge pieces o f rock r o l l e d down the mountains. I t i s s a id t ha t t he waters of Pescadero Creek became muddy in a moment, and t h a t the surface was covered with bubbles, which burs t with a s l i g h t repor t and a small flame when a match was applied t o them.

About 2 miles e a s t of t he town [Pescaderol, on t he north bank of Pescadero Creek, a landslide i n t he shape of a half-moon, its axis lying N. 23' W . , had s l i p t dawn toward t he bed o f the stream. The grea tes t ve r t i c a l displacement a t t he top of t he s l i d e was 15 f ee t ; the distance from i t s apex t o the road about 85 f e e t ; and t he span from end t o end along the road about 220 f ee t . No so l i d rock was exposed by t he s l i d e . The road had d r o p 6 fee t a t t he south end, and 8 f ee t a t the north. Only a few cracks appeared on the surface of the pa r t which had s l i p t . The creek lying d i r ec t l y below the road had apparently received very l i t t l e s o i l from the lands l ide .

r * a t San Gregorio * r Cracks from 12 t o 18 inches wide appeared i n the cu l t iva ted bottom-land * * .

Chief Engineer Rogers and par ty came down from up the coast Wednesday. tie reported t ha t a t San Gregorio, San Mateo county, a few miles beyond Pescadero, he saw f i s su r e s i n the ear th from a few inches t o f i f t e e n f ee t i n width from which a l i t t l e sand and water was being forced out .

* a couple of miles f a r t he r e a s t [of San Gregorio], the creek was dammed up t o a depth of 6 f e e t by a s l i d e from i t s southeast bank ( a t 32, map No. 22) r * * .

On the Pomponio Creek road * r . A b ig s l i d e above the l a s t house forced t he observer t o leave t he road and take t he t r a i l , which re jo ins t he road a ha l f mile f a r t he r on.

Miss L. E . Bell repor t s t ha t near Be l l v i l l e a small a l k a l i f l a t was ra i sed about 3 f ee t . There was a landslide i n to the road f o r a distance of 300 f ee t , the height of t he s l i d e being 100 fee t (34, map No. 22).

Near the Weeks ranch house, between La Honda and the s m i t of the r idge on the road leading t o Redwood, an inconspicuous crack was noticed running e a s t . I t was about 2 inches wide, with no ve r t i c a l movement evident . The north s i de of t he crack, however, had moved

TABLES 6 9

TABLE 6,Specif ic descriptions of ground failures in the Son Francisco Bay counties region--Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on ure ure ra- earth- No. No. type cy quake

Quotation

- -

f u l l y 3 f e e t eastward. The crack simply marks a b ig s l i d e which has been s l ipp ing fo r years, and which descended 3 f ee t during the earthquake.

98 C 1906 Lawson and others, Farther west up the road which loops toward Langley H i l l , a big crack @ 1908, running eas t and west, caused by a s l i d e , showed a drop of 8 inches

p. 264. on the nor th s i de ; and fmm he re on dawn t o the Alpine road the road was badly cut up with s l i de s , but was not impassable. On the s teep grade of Langley H i l l a - s l i d e had moved 30 fee t .

99 C 1906 Lawson and others, 1908, p. 264.

C 1906 Lawson and others, 1908, p. 389.

C 1906 Lawson and others, 1908, p. 106.



Following the Alpine road up Corde Madera Creek, cracks were camon on the outs ide or f i l l e d port ion of the road, and these were generally p a r a l l e l with the embankment. The s teep southern slope o f the r idge j u s t north of the Alpine road, along i ts lower course, was favorable t o landslips. A t many places huge masses of rock had been thrown down from these steep b lu f f s i n t o t he road, completely blocking i t up. On the south s ide o f the creek the slopes were no t favorable t o land- s l i p s , but there were several o f them; and a t one point , about a mile from the summit of the r idge where t h i s road en ters the Page M i l l road, one s l i d e car r ied away t he en t i r e roadbed fo r a distance of about 300 fee t .

At many places on the south s i de of Corte Madera Creek, huge masses of rock had been thrown down from the s teep b lu f f s i n t o t he road, completely blocking it. About a mile from the summit of the r idge, where t he Alpine road en t e r s t he Page Mill road, a s l i d e car r ied away the e n t i r e roadbed for a d is tance o f about 300 fee t .

Road fmmJudge Allen's southward.--Between 3 and 4 miles southeast of Portola, many cracks were v i s ib l e extending i n a l l d i rec t ions . Several showed an u p l i f t on the e a s t o r northeast s i de , which is also t he downhill s ide . Some cracks were from 4 t o 5 inches wide, and had-a ve r t i c a l throw o f near ly a foot . In o the r places the downhill s ide had been t h ru s t upward, and pieces of t he c rus t shoved as much as 4 inches over the uphi l l s ide. Near t he top o f the r idge, j u s t before reaching t h e point where the t r a i l branches o f f , a 4-inch crack running S. 63' E. showed a 4-inch upthmw on the northeast (downhill) s ide. Southwest of the r idge and about 100 f ee t below the t r a i l , an o ld landslide da t ing back t o some time within the pa s t year, covers about 2 acres. Around t h i s s l i d e the ground appeared t o have been much cracked recently.

Many o ther earth-avalanches of minor importance were caused by the earthquake i n various pa r t s of t he Santa Cruz Mountains. A t Hidden v i l l a , 2 miles northwest of Black Mountain, la rge blocks of rock are reported t o have r o l l e d dawn the slopes.

Page M i Z Z road.--In following t he Page Mill road up Corde Madera Creek [now named Matadero creek] from Mayfield, the f i r s t noticeable t r a ce of the earthquake was a crack crossing the road due ea s t and west, i t s width varying from 0.5 t o 1 inch. IVagon-tracks showed a l a t e r a l displacement o f 1 inch, the north s ide of the craek having mved west, r e l a t i ve ly t o i ts south side. This crack was t raced a shor t distance i n t o the f i e l d s beside the road, where it disappeared. Several smaller cross-cracks in te rsec ted it a t in te rva ls . There was no apparent ve r t i c a l displacement. About 100 yards f a r t he r south were 3 smaller cracks varying from 0.25 t o 0.75 inch i n width. One ran N. 53- W., and another N. 23' W. The l a t t e r , being only 8 f e e t from a culver t crossing under the road, appears t o have been deflected by t h i s from a course running mre nearly east . Here again was no evidence of ve r t i c a l throw. Going on up toward the Alpine road from t h i s point , more and more cracks were found, running approximately ea s t and west, with the exception of several


TABLE 6 .Spee i f i c descriptions of ground failures in the Son Francisco Bay counties region-Continued

Santa C m Mowtains--Continued


103 A 1906 Lawson and others, 1908, p. 264, map 22.

104 C 1906 Lawson and others, 0 1908,

p. 265.


106 0 C 1906 Lawson and others, 1908,

• p . 266.

107 A 1906 Lawson and others, • 1908,

p. 265, m p 22.

108 A 1906 Lawson and o thers , 1908, p. 265, map 22.

north and south ones where the road ran closely p a r a l l e l t o the stream. Less than a mile from the f i r s t crack, groups of cracks were accompanied by small s l i d e s of d i r t from the h i l l t o the west of the road, and f a r t h e r on from the b luf f t o the e a s t of it. The cracks ran nearly p a r a l l e l with t he ax is o f t he branch va l ley lying northeast snd southwest. Farther up the road, large cracks began t o appear among smaller ones running pa r a l l e l . The f i r s t o f these was 2.5 inches across and ran S. 13- E., with a downthrow o f 1 inch on the eas t s ide , and could be t raced from 50 t o 100 f e e t on e i t h e r s i de of the road. For a mile f a r t he r up the road, the cracks became so nmerous and complicated t ha t it was impossible t o map any indi - vidual ones. They in te rsec ted and ran i n a l l d i rec t ions , and were a l l of varying widths, the la rges t seen measuring 8 inches across. The s i z e of t h i s crack, however, was probably p a r t l y due t o i t s pos i t ion on t he s i de o f a h i l l . The l a rge r cracks could be traced fo r several hundred fee t . In some places crushing had taken place, and the layer of macadam on the road had been humped up and broken. In t h i s same area are many small landslides, some large enough t o cover the road; one has occufred s ince t he earthquake. [Some of these cracks may have been f au l t ruptures, see McLaughlin, 1974.1

On Purissima [sic] Creek [unclear whether i n Santa Clara County o r on a d i f fe rent creek of the same name i n San Mateo County] a s l i d e f i l l e d the road for a length o f about 100 f ee t ; another, between 0.25 mile and 0.5 mile long, dammed the creek t o a depth of 25 o r 30 fee t .

On the road from C la r i t a Vineyard t o the Allen place (a t 18, map. No. 22), severa l small cracks 0.25 t o 0.5 inch across ran ea s t and west; nmemus cracks i n t e r s ec t ed (near 18, map No. 22) i n various d i rec t ions , while some l a rge ones running pa r a l l o l t o tho contour l i ne s were probably due t o ear th sl ipping. [some of these cracks may have been f a u l t ruptures , see McLaughlin, 1974.1

On the Bear Creek road, southwest of Woodside, there were many cracks caused by landslips down s teep banks.

Small cracks appeared i n the ground a t Lobitos, and a small s l i d e occurred i n the road 0.25 mile up t he stream.

* * * a crack ea s t o f t he road below Purisima, due t o a lands l ip , extended f o r about 1,000 f ee t near ly nor th and south; and an ear th- s l i d e on the s i de of a h i l l a mile o r more f a r t he r south was about 100 yards long and 80 f e e t across.

Fallowing the t r a i l from King's Mountain House down Purisima Creek, a large s l i d e on the northeast s i de of t he creek had f i l l e d t he mad t o a width of about 100 f e e t ( a t 23, map No. 22). The buildings a t Hatch's Mill, j u s t below (24, map No. 22) were not damaged, but a l i t t l e f a r t h e r dom severa l cracks were found, one 8 inches wide and running S. 23' E .

On the northeast s ide of the creek, j u s t below Borden's Mill, a big s l i d e had dammed the creek t o a depth of 25 o r 30 f e e t ( a t 25, map No. 22). The s l i d e was between 0.25 and 0.5 mile long. The buildings a t the m i l l showed no damage, but a bridge j u s t above the m i l l was crusht by a s l i d e from the south s ide of the creek.

TABLES &9 99

TABLE 6 .Spec iFc descriptions of ground failures in the San Francisco Bay counties region-Continued

Santa C m z Mountains--Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on ure "re ra- earth- No. No. type cy quake

Quotation

-

109 A 1906 Lawson and o thers , i r the bridge aver P i l a r c i t o s Creek, north o f the town of 1908, Half Moon Bay * * * ( a t 30, map No. 22) * * was badly cracked, as p. 266, were the approaches a t both ends. Ju s t south of the bridge, several map 22.

0 small cracks i n the low ground west of t he road permitted water t o spout up, bringing sand with it.

110 20 A 1906 Lawson and a the r s , One * . * [flow landslide] was formed i n the h i l l s bordering t he 1908, t e r r ace a t Half Moon Bay, immediately south of Frend~man Creek, 1.5 p. 395, miles north of the town, and a mile from the sea, a t an elevation p l a t e 132A. of 100 f ee t . It i r pictured i n p l a t e 132A. A t t h i s place the ear th

caved away i n a crescent-shaped area on a slope of only IS9, and flowed out i n two long arms so as t o leave a hole 4 f e e t deep, surrounded by v e r t i c a l walls of unaffected s o i l . The flow occurred a t a f a i r l y high point on a gently undulating inc l ine . The d is - charged ear th was divided by a mound, a t a point 150 f ee t below the summit of the arc, and followed two courses whirh were determined by gu l l i e s on both s ides . Much of the dLbris over-flowed the cent ra l mound a t the same time, and inundated the barley f i e l d s t o a depth of 2 t o 4 f e e t , f o r 100 f e e t f a r t he r . On both s ides o f the cent ra l mound t he caving away continued t o t he same depth. In the left-hand fork i t s top t within a few f ee t , and t he flow did not extend very f a r beyond. In t he right-hand fork a cut 100 fee t long and 50 f e e t wide was made, the ear th flowing down from it 250 f ee t f a r t he r over the grain f i e l d , as shown i n p l a t e 132A. Thus the whole length of the s l i d e was 500 fee t . The width of the main hole iras on the average about 100 f ee t , and t he length, as already mentioned, 150 f e e t not including the arms.

In t h i s hollow i n t he h i l l s i d e s many dry blocks o f sod carrying growing grain--usually i n an upright position--were l e f t stranded 4 f e e t below the surface of the h i l l by t he removal of the subsoil . The fence t ha t c ros t t h i s irea was broken and car r ied away and pa r t l y buried. lVhere the caving ceased i n the r i g h t fork, a r idge of debr i s was p i l ed up across the mouth of the hole, much higher than t he stream of loose material t ha t flowed f a r t he r . Similar r idges were heapt up across the path of the flow, where the breaking away of the h i l l s t op t i n the o ther arm and a t the upper end of the cent ra l mound. The south or r i g h t arm of the flow extended down the h i l l a t an

angle gradually decreasing from 18' t o l e s s than 5'. Large pa r t s of the fence were car r ied on i ts surface for 300 fee t .

P la te 132A gives a de t a i l ed view o f the lower extremity of the r i gh t arm. The stream came t o an abrupt s top , l i ke a quickly cooled lava flow, and preserved a face 1 t o 2 f e e t i n height above the a ra in f i e l d . The surface o f the flow consisted la ree lv of b l o c k of sod, ~ 5 ~ 8 1 1 ~ almost u ~ r i a h t , which were car r izd hown from t h e hole without much moisiening, o r transformation i n to material capable of flowing. The bulk of t he floiv was a moist aggregate of ear th fragments possessing something o f t h e i r previous form and eradine i n t o mud. which assumed a semi-fluid consistency underneath. he bottom o f the hole, and t he flow i t s e l f , remained too muddy t o walk on fo r weeks a f t e r t he earthquake, and t he f i e l d below the lower end o f t he l a rge arm was l e f t marshy, tho it had not been s o before. I t is t o be noted t ha t several f a i r l y heavy r a in s followed the earthquake a f t e r an i n t e rva l of several days, and before these earth-flows were v i s i t ed ; but these were not su f f i c i en t t o account f o r t he amount of moisture observed. The chief e f f e c t o f the water was i n the ground a t a depth of 3 o r 4 f e e t below the surface. I t rendered t he s o i l su f f i c i en t l y f l u id t o enable it t o flow doim the gent le slope, probably pa r t l y oozing from under t he surface c rus t and p a r t l y transport ing the sad with it. Most o f the surface was car r ied down with t he main flow, the stranded surface blocks t h a t remained i n the cavity being account- ab le , for as fragments from the broken edges subsequently giving way and being car r ied only a shor t d i s tance as t he upper end of the flow came t o r e s t . In t h i s way, probably, t he walls were trimmed, f o r the cut i n general was l e f t remarkably clean.


TABLE 6.Specif ic descriptions of ground failures in the Son Francisco Bay counties region-Continued


Loca- Fig- Fail- Accu- Year of Reference t i on "re "re ra- earth- No. No. type ey quake

Quotation

111 C 1906 Lawson and others, Another flow o f s imi la r character [see locs. 110, 112, 113, 114 and 1908, 1231 took place 3 miles north-northwest of the town of Half Moon p. 396, Bay, on the creek next west of Frenchman Creek. I t i s shown i n

21A p l a t e 1328, p l a t e s 1328 and 133A. On t he morning o f the earthquake an acre of p l a t e 133A. t he gently sloping a l l uv i a l f l oo r of a broad, shor t va l ley t r i bu t a ry

2lE t o the main creek on t he e a s t caved and flowed out , leaving an excavation 10 f e e t deep, where before i t had been almost l eve l and where there had been no stream channel. In t h i s case, t h e water already gathered i n t h i s basin-l ike valley, which here had had no means of prompt escape, was an important a i d i n the formation of the flow * . The presence of a la rge amount of water and t he fo r c i - b l e movement during the earthquake shock resu l ted i n the loosening and undermining of the ground and i t s t ranspor ta t ion as a f l uen t mass. The angle o f slope was about 5'. The flow car r ied out thousands o f tans o f ear th i n t h i s manner and spread i t over about 2 acres of meadow land, t o an average depth o f 1.15 t o 3 f e e t . P la te 1328 gives a view of t h i s earth-flow, showing the p i t from

which it w a s derived. Covering much of t he surface of the flow and t he f l oo r of the hole are t o be seen blocks of sod which have been car r ied r i g h t s i de up as i f t he material had moved en rnosse. The amount of water i n evidence shows c l ea r l y how the ear th was softened and enabled t o move. The p ic ture was taken two weeks a f t e r t he earthquake. A t t h a t time water was s t i l l seeping up from underground, and out of t he lower port ions of t he broken walls, while t he ground near t he surface o f t he va l ley was qu i t e dry. The water had formed two de f i n i t e r i v u l e t s t h ru t he dkbris , a t gn elevation above the surrounding meadow, and w a s running i n continuous streams, f a s t cu t t i ng a channel f o r i t s e l f and removing t he s o f t material . Consid- e rab le water iras darned back i n t he hole by a &foot r idge of d&ris p i l ed across t he mouth o f t he hole, as i n t he case o f the previously described earth-flow [loc. 1101. This mound of ear th , along the l i n e where the stream l e f t the caved-in area and flowed over the preexis t ing slope, was probably p i l ed up a t t he l a s t by the remnants of t he flow gl id ing down and heaping themselves up as a b a r r i e r a t the mouth of the hole. The cavity, about an acre i n extent , has lo-foot walls which gradu-

a l l y decrease i n height lower down the valley, t he bottom of t he hole being more nearly leve l than t he valley-floor. P la te 133A shows pa r t of t h i s flow i n de t a i l .

Some of t he great blocks of sod around t he edges have not been removed, a l t h o t he material from underneath has gone. Concentric cracks not v i s i b l e i n t he p i c tu r e s extend around t he edge of the hole and fo r 50 f ee t above i t s upper end, showing t ha t the area af fec ted i s broader than appears a t f i r s t s i gh t , and t ha t the work is not ye t a l l accomplished. The material of t he valley-bottom is a coarse, arkose ear th , derived from decomposing grani te , and containing many rock fragments. A flood o f ear th covers about 2 acres of the meadow. Water was

present i n t h i s earth-flow i n grea ter amount than i n any other t ha t was examined. The nature o f t he material may be judged o f by the abrupt face of t he stream where i t s topt . The edge makes a s teep angle with the meadow and r i s e s t o an average height o f 2 f e e t above it. Yet the f a c t t ha t t h i s mass of ear th was able t o move more than 300 f ee t a f t e r i t l e f t the lower end o f t he hole, and spread i n to an even and t h in layer over a wide extent of near ly leve l meadow, shows t ha t it was f a i r l y s o f t . It was moved an a basal layer of semi-fluid mud and sand, with the a id of t he weight of the over- ly ing and pa r t l y d is in tegra ted ear th .

112 C 1906 Lawson and others, About 4 miles e a s t of Half Maon Bay, j u s t off the south edge o f 1908, the San Mateo sheet , there was another large ear th-s l ide s imi la r p. 252. t o the two [earth-flows, locs. 110 and 1111 already mentioned.

TABLES 5 9 101

TABLE 6 .Spec i f i c descriptions of ground failures in the San Francisco Bay counties region--Continued

Santa Cruz Mowrtains--Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t ion "re ure ra- earth- No. No. type cy quake

113 B 1906 Lawson and others, The l a rge s t of the earth-floris seen occurred i n the canyon south of 1908, the house of M r . Nunez, 2.5 miles east-northeast of t he town of p. 397. Half Moan Bay, a t an elevation of about 500 f ee t . I t originated i n

a manner s imi l a r t o the o thers Llocs. 110, 111, 112, and 1141, but i n a canyon along which there is a d i s t i n c t but ord inar i ly dry stream channel. A long, i r r egu l a r hole from 4 t o 7 fee t deep was excavated near the head of the va l ley , and a great volume o f ear th flowed down i t s curving course f o r 0.25 mile, as f a r as t he Nunez house, and there s t op t , being i n pa r t d iver ted i n t o t he main creek t o which the valley i s there t r ibu ts ry . According t o the testimony of witnesses the flow reached t he end of the 0.25 mile i n 0.5 hour a f t e r the earthquake shock. I t was seen g l id ing slowly down and engulfing t he archard j u s t back of the house. According t o observers on t he Nunez ranch, t he earth-flow was not accompanied by any water; but two weeks l a t e r , when examined by the wr i te r , it preserved every evidence of having been muddy. Especial ly was t h i s t r u e a t t he bottom, where great masses of mud still had t he consistency of j e l l y . I t i s probable t h a t there was no flowing water on the surface of t h i s o r other earth-flows a t the t i n e o f t h e i r fo-nation, and t ha t the presence of water i n the flow was not evident t o the casual observer because o f t he comparative dryness o f t he material on its upper surface. The slope of the canyon dom which the moving body of land crawled

is about 25' near t he head and decreases t o 15- f a r t he r down. The flow f i l l e d t h i s t o a width of 100 f ee t on t he average, and t o a depth varying from 10 t o 20 f ee t . The i n e r t i a of the mass is i l l u s - t r a t e d by the f a c t t ha t i n the ear ly stage of the flow the ear th was pi led 20 fee t higher on the h i l l , on the ins ide of the b ig curve made by the canyon, not f a r beloir t he p i t , than it was when t he flow came to r e s t . The marks a t t h i s elevation were probably made very soon a f t e r the main mass was discharged from the cavity, before it had spread very widely. The cent ra l port ion of t h i s earth-flow is

p l a t e 1318 pictured i n p l a t e 1318, where it appears as a r idge many f ee t high r i s i n g above the t a l l grass on the h i l l s i d e , on the r i g h t of the p ic ture . The pressure of t he material a t the head of the flow, as i t s t a r t ed , was so great t h a t the e a r t h bulged up over the s ides i n places, i n such a way as t o force upirard great blocks of sod and turn them on edge o r completely over, away from the rim of the hole. The flow assumed the form o f two l a t e r a l r idges and a cent ra l de-

pression, or channel. The r idge on the west o r inner s ide of t he curve was considerably the higher. The form was due p a r t l y t o the concavity o f the valley; but ch ief ly , i t is thought, t o the tendency of the more f l u id material t o follow the deepest possible path along the gully under t he center of the flow. Thus the d r i e r mate- r i a l was retarded a t the s ides . Subsequent t o t he f i r s t s t a r t i n g of the flaw, a stream of semi-fluid mud and sand continued t o run dawn the cent ra l channel, covering i t s s ides with a coating of mud and leaving flowage s t r i a t i o n s on it. This channel and i t s markings are exhibited i n p l a t e 1318. Two weeks a f t e r the earthquake, when the photograph was taken, water was running i n t h i s channel and had cut dawn in to i t several f e e t deeper. I t s bottom, however, was s t i l l from 5 t o 10 f ee t higher than t h e bottom o f the underlying pre- &is te rn water course, where water had not flowed before a t t h i s time of the year. The man i n the p ic ture i s standing a t the bottom of t he gully. To the l e f t of him, the hamer and note-book mark the top of one of the pa r t s of t he l a t e r a l r idge which is here divided i n to several h m o c k s . To the r i g h t i s t he o ther and higher l a t e r a l ridge. The foreground was formerly covered by a dense th icke t of willow t r ee s . These willows have been completely buried, excepr a t the s ides where some dead branches protrude. A fence t ha t c ros t t he canyon was to rn away fo r 100 f ee t , and not a t r a ce of it could be found. The fence shorn i n the p ic ture i s one neirly b u i l t i n i t s place.



Laca- Fig- Fail- Accu- Year of Reference t i on ure ure ra- earth- No. No. type cy quake

Quotation

114 B 1906 Lawson and o thers , Two other smaller earth-flows occurred j u s t over the h i l l westward 1908, from the l a s t one described ~ l o c . 1131. They are sham i n p l a t e p. 397, 1338, t he canyon on t he l e f t being t he one occupied by t he Nuner

22 p l a t e 1338. flow. One of these 2 earth-flows, t ha t a t t he r i gh t of the p ic ture , s t a r t e d near the top of the r idge i n a depression i n t he slope, formed a hole 75 f ee t long and 40 f ee t wide, and coursed dam a narrow runnel having a gradient of 25' t o the bottom of t he h i l l , a distance o f 600 f ee t . Enough ea r t h issued t o f i l l ur, the r a t h e r deep d i tch i n the gully c l e a r t o the bottom of the h i l l and ts bury the grain f i e l d an both s ides t o a depth of 1 t o 2 f e e t . I n t h i s case, as i n the preceding one, there were formed l a t e r a l r idges higher than the center , so as t o leave a groove between. Down t h i s channel there flawed s o f t e r material , which l ined t he s ides of the l a t e r a l r idges with a smooth coat of mud and l e f t conspicuous flowage marks. The flaw thus ra i sed a d i tch f o r i t s e l f above the l eve l of the slope. The earth-flow probably assumed t h i s form by leaving behind, a t the s i de s , the material l e a s t capable o f flowing, and by concentrating i t s most l i qu id p a r t s along t he deep cent ra l l i ne . The other earth-flow was near by, an the convex face of the knoll

i n the center o f the p ic ture . A s imi l a r cavity was produced, from which the contents !rere spread out broadly. I t is a good example o f the s t a r t i n g o f a gully, as there was no depression before. One branch of t h i s earth-flow came s t r a i g h t down the h i l l and s l i g h t l y toward the canyon on the l e f t ; the o the r branch came down toward the gully i n which t he first-mentioned of these two earth-flows occurred. Thus drainage l i ne s were s t a r t ed which ult imately may separate the cent ra l h i l l from the r idge on the r i gh t , of which it i s no!? a continuation, The l e f t arm o f the flow an the h i l l may develop a channel, as enplained below, which w i l l cause t he drainage from t h i s h i l l , which i s now toward t he foreground, t o pass i n t o the canyon on the l e f t .

115 C 1906 Lawson and others, From Half Moon Bay t o San Mateo, there were several la rge s l i d e s 1908, of different character from those already mentioned [earth-flo~rs] . p. 252, These r e su l t ed from the s l ipp ing of large masses o f rock, many of p l a t e 124C, the fragments i n one of t he s l i d e s being over 20 f ee t i n diameter. p l a t e 1268. (See p l a t e s 124C and 1268.)

C 1906 Lawson and others, Near Half Moon Bay considerable masses of grani te were dislodged 1908, an a - s t e ep slope. (Plate 124C.) On t he road along P i l a r c i t o s p. 389. Creek, an earth-avalanche brought down b ig blocks o f sandstone

upon the road. (Plate 1268.1 [See a lso loe. 121.1

116 C 1906 Lawson and others, J u s t southeast of the house [on Cah i l l ' s r idge] i s a depression i n 1908, the r idge , across which furrows and cracks formed s im i l a r t o those p. 253. along the main f au l t - l i ne , but not extending more than severa l hun-

dred fee t . These cracks do not seem t o have been landslide cracks, for they are on t op of t he r idge and on a f l a t p iece of ground. [See a l so loc . 12o.l

B 1906 Lawson and o thers , A house on the northwest s i de o f Half Moon Bay road, 2,000 f e e t 1908, southwest of the dam [through Crystal Springs Lakes], was thrown p. 253. from i t s foundations, while some 200 f e e t northwest o f t h i s house

there was a s l i d e i n the canyon.

8 1906 Taber, A s t r i k ing evidence of [fault] displacement i s shown i n the ear th 1906, dam tha t divides t he Crystal Springs Lake. This dam i s about 500 p. 308, fee t i n length, and the road from San Mateo t o Half Moon Bay runs f ig . 7. along i t s c res t . The accompanying sketch (Fig. 7) [See f i g . 7 a t

end of tab les ] shows t he pos i t ion and d i rec t ion of the cracks t ha t were formed i n t he dam. The la rger cracks [c lear ly secondary] are about 6 inches wide and are p a r a l l e l with t he dam. Smaller i n t e r - sec t ing cracks were formed near t he nor theas t end of t he dam along

TABLES E-9


Loca- Fig- Fail- Accu- Year of Reference Quotation t i on "re "re ra- earth- No. No. type cy quake

t h e probable l i ne o f the f au l t , and the raad rras o f f s e t about 6 f e e t a t t h i s poin t . The fences on both s ides of the raad were broken i n a number o f places, and t he unbroken boards were bent and arched so as t o give a serpentine appearance t o the fences. The wires of a telephone l i n e crossing the dam sag i n great loops. I t seems probable t ha t t he t o t a l [ fau l t ] displacement i s grea ter

than ?he amunt t ha t may be d i r ec t l y measured a t any place along the l i ne of the f rac ture , for there is evidence o f drag i n the s o i l f o r a considerable distance on both sides. Water-pipes a t a distance of several hundred fee t from the fau l t - l ine have been pulled apar t , telescoped, o r bent i n t h e d i rec t ion of the movement, and fences formerly s t r a i gh t have been bent i n t o a s l i g h t curve f o r a d is tance of 200 o r 300 yards from the f rac ture .

119 C 1906 Lawson and others, There were examples of such s l i p s [ landslides] along the coast 1908, h i l l s north San Pedro Point, near t he road halfway between San Bruno

0 p. 398. and San Andreas Lake, near the road from Beimont t o Crystal Springs Lake, 0.5 mile southeast o f the San Matea Alms House, and i n many o ther places on the San Francisco Peninsula. I n some places bare ridges had t h e i r l i ne s of symmetry broken i n t o l i t t l e knolls and i r r e g u l a r i t i e s by these s l i p s , a common occurrence i n the h i l l s of sof t sand formations i n t he northern p a r t of the San Francisco Peninsula.

C 1906 Lawson and others, Thru the h i l l s west o f Belmont no cracks nor b ig landslides-were 1908, found, but there were small landslides along the road leading from p. 246. Belmont t o Crystal Springs Lake.

C 1906 Lawson and others, Another pecul ia r phenomenon was observed upon Cahi l l ' s Ridge, l e s s 1908, than 1 mile northwest of the cracks mentioned [lac. 1161. In an p. 253. area of limestone, a small patch some 30 f e e t in diameter was to rn

up as tho it had been plowed and harrowed, and no la rge pieces of sod were l e f t i n t a c t . Around t h i s i n various places lrere cracks of a few inches i n width, with one o r two over a foot wide. There was a s l i g h t dawnthrow an t he uph i l l s i de t o be noticed i n some of these cracks, which eliminated the pos s ib i l i t y t ha t they were cracks pre- paratory t o landsliding.

121 C 1906 Lawson and others, Following the road along P i l a r c i t o s Creek toward Half Moon Bay, 1908, many cracks and s l i d e s were found on t he ocean s ide of the r idge, D. 265. but few on the ea s t s ide . A l l of these seemed due t o s l ipp ing of

t he earth. At one place there had been such a large slid;-[sic a lso loc. 1151 t h a t big blocks of sandstone had f a l l en down in to the road. Here and there along the road b ig cracks had opened, pa r a l l e l with the road and the creek where the slope i s very steep, and pro- mising t o make the road impassable by landslides, should a heavy r a in come.

122 C 1906 Lawson and others, On the south face of Scarper Peak, and on the southwest face o f Ox 1908, H i l l , there were several landslides both large and small. p. 252.

123 C 1906 Lawson and o thers , South of Montara Point, i n t he low foo t -h i l l s north of Half Moon lil 1908, Bay, there were two large law-angle landslides o r earth-flows. One

p. 252. of these landslides was on the low foo t -h i l l s facing the ocean; t he o ther an the northeast bank of Frenchman's Creek [loc. 1101, several mile? northeast of Half Moan Bay.


TABLE 6.Specif ie descriptions of ground failures in the Son Francisco Bay counties region-Continued

Santa CWZ Mountains--Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t i on "re "re ra- earth- NO. No. type cy quake

124 C 1906 Lawson and o thers , On the southwest face of Montara Mountain, near ly a l l of which i s 0 1908, v i s i b l e fmm the road, no landslides of any s i r e were observed.

p. 252.

125 C 1906 Lawson and o thers , On Sawyer's Ridge, about 9 miles north o f t he region described on 1908, Cah i l l ' s Ridge Clocs. 116, 1201, there were cracks several hundred p. 253. fee t long almost a t the top o f the r idge. These were p a r a l l e l t o the

l i ne of the main f a u l t , which i s a mile t o t he ea s t , and there was a marked downthroir o f from 2 t o 3 inches on the southwest s ide , which i n t h i s case was the uph i l l s i de .

126 C 1906 Lawson and others, There were a l so severa l such s l i d e s [small earth-avalanches] on the 1908, grani te slopes o f Montara Mountain, f a r t h e r north i n the San Francisco p. 390. Peninsula.

127 C 1906 Lawson and o thers , South from the Devil 's S l ide t o the f i r s t small coast va l ley , there 1908, were landslides along t h e c l i f f s . The rock i n t h i s v i c in i t y i s mas- p. 252. s ive grani te , but the landslides showed t h a t the rock had d is in te -

grated for a considerable d is tance below the surface and t he s l i d e s were i n t h i s decomposed rock. Wherever the railway bed [Ocean Shore ailw way] was f i l l e d o r b u i l t out with t h i s material , there rias more or l e s s s l i d ing and s e t t l i n g , caused by the earthquake.

128 C 1906 Lawson and others, Ju s t north of the point known as Devil 's S l ide , there was a land- 1908, s l i d e o f t he whole face of t he west end of Montara Mountain. It p. 252. s t a r t e d a t about 800 f e e t above the sea, and swept dam carrying

many hundred fee t of roadbed along with it. The material t ha t s l i d was sandstone and grani te , but it seemed t o be much weathered and softened i n places, so t h a t it was loose ground.

C 1906 Lawson and others, One earth-avalanche t o the north o f the Devil 's S l ide s t a r t e d . 1908, about 800 fee t above t he shore and swept the face of the c l i f f ,

p. 387. carrying away several hundred f ee t of roadbed. The s l i d e occurred near the contact of sandstones reposing on grani te , and both kinds of mck were involved. Smaller earth-avalanches occurred f a r t he r south on the s ea - c l i f f s .

129 C 1906 Lawson and others, From San Pedro Point southward fo r about 1.5 miles, t he c l i f f s 1908, r i s e t o heights of from 400 t o 800 f ee t . The railway company had p. 252. cut a bench fo r i t s roadbed several hundred f ee t above the ocean.

This roadbed, being la rge ly i n s o l i d rock, was f o r t he most p a r t not much injured; but i n some places i t was ob l i t e r a t ed by rock

0 s l i d e s t ha t came from above.

130 C 1906 Lawson and o thers , To t he south of Mussel Rock there were several small earth- 1908, avalanches along the c l i f f s , and numemus cracks were formed near p. 387. the brink of the c l i f f s which w i l l i n fu ture doubtless lead t o fur -

t h e r f a l l s from the c l i f f - face . Near San Pedro Point there was a large movement o f the ear th on the face of the high c l i f f .

C 1906 La~uson and others, In the va l ley of Laguna Salada, the Ocean Shore Railroad had a 1908, temporary t r e s t l e erected for making a f i l l i n the va l ley up t o p. 251. required grade. This t r e s t l e was twisted and thrown out of l ine ,

and the ear th sank along the newly f i l l e d roadbed. * * Along the base of the c l i f f s south of Laguna Salada, there irere

several small s l i de s . some from the face of the h i l l s and others i n the newly graded roadbed. There were many small cracks along

TABLES 5-9 105


Loca- Fig- Fa i l - Accu- Year of Reference t i on "re ure ra- earth- NO. No. type cy quake

Quotation

-~ ~~- ~-p~

t h e tops of the c l i f f , p a r a l l e l t o its edge, showing t ha t t he face of the b lu f f was shattered, and t h a t more ear th might s l i de . One big rock pinnacle, which had been l e f t above t he roadbed as a land- mark, and which had seemed a l i t t l e dangerous before, was shaken down.

132 23 C 1906 Lawson and o thers , South of the Golden Gate, t he most notable earth-avalanches were 1908, along the s ea - c l i f f s between the c i t y and Mussel Rock. This c l i f f p. 387, has a length o f about 6 miles and ranges i n height from about 100 p l a t e 129C, f e e t up t o 700 f ee t , and i s cut a l m s t wholly i n the s t r a t a of t he p l a t e 1290. Merced (Pliocene) s e r i e s , which are inc l ined a t angles varying from

15' t o 75'. The rocks are fo r t he most pa r t r a t he r so f t and incoherent , tho there are numerous well-cemented and indurated beds i n t he s e r i e s . This c l i f f converges on the f a u l t a t a small angle, and i n t e r s ec t s it a t its south end near Mussel Rock. The c l i f f was severely shaken and great quan t i t i e s of e a r t h and rock were caused t o f a l l or s l i p down. The great e a r t h - s lmp a t Mussel Rock (Plate 129C, D) was a l so notably accelerated.

C 1906 Lawson and others, All along t h i s l i n e of c l i f f s [between Lake Merced and Mussel 1908, ROC^], and fo r a shor t undetermined d is tance inland, the rack masses p. 241. were cracked, broken, and t raversed by narrow f i ssures . These

e f f ec t s grow more and more numerous and o f grea ter and grea ter mag- ni tude u n t i l , a shor t distance north of Mussel Rock, the f a u l t i s reached. t * * All along the faces o f these c l i f f s , much material f e l l o r s l i d down t o t he beach.

24 C 1906 Lawson and o thers , Along the coast from Mussel Rock t o Lake Merced * *,* . Along t he 1908, face of these c l i f f s t he Ocean Shore Raillray had s t a r t e d a grade a t p. 250. an elevation of about 300 fee t above t he t i d e leve l . Along t h i s

bluff a la rge amount of ear th s l i d down the slopes a t the time of the shock. This caving of the banks was due t o t he nature of the s o i l , the proximity t o t he fault-zone, and the disturbance o f natu- r a l slopes due t o the r a i l r oad t e r r ace near t he top.

In places t h i s slope toward t he ocean was brought about t o t he angle of the repose o f t h i s material and t he roadbed was en t i r e l y destroyed fo r a distance of 3 miles.

C 1906 Lawson and others, Near Mussel Rock pa r t of the roadbed s l i d f a r about 500 f ee t and 1908, on the h i l l s i d e above the road there was a long crack which was the p. 250. beginning of a s l i d e t ha t might have taken a la rge pa r t of the h i l l .

C 1958 Coffman, 1058. December 11. * * A minor landslide occurred on S t a t e High- 1973, way 1, west of Daly City. Magnitude 4.7. p. 179.

A 1957 Coffman, 1957. March 22 and 23. r * * Sta t e Highway 1, near Mussel Rock, 1973, was blocked by landslides; highway pavement was cracked extensively. p. 178. * t * a la rge reinforced concrete reservoi r cracked.

133 0 B 1906 Lauson and others, There were several la rge landslides on both the southwelt and 1908, northeast s ides o f the [l~ood's] gulch, and a t the ocean t he amount p. 250. of d i r t tha t had f a l l en was very large.

A 1906 Lawsan and others, On April 25, t he wr i t e r was on the edge o f the c l i f f s near Woad's 1908, Gulch. About 3 P.M. of t ha t day there was a shock with an in ten- p. 250. s i t y estimated t o be b e t ~ e e n V I and VII. At t ha t time t he c l i f f s

shook l i ke 50 much ge la t ine , and it was necessary t o hold on t o prevent f a l l i ng . On the north s ide of t he canyon, hundreds of tons of ear th f e l l even with t h i s l i g h t shock.


TABLE 6.Specif ic descriptions of ground failures in the Sun Francisco Buy counties regian--Continued

Loca- Fig- Fa i l - Aceu- Year of Reference t ion ure ure ra- earth- No. No. type cy quake

Quotation

Along t he top o f t he c l i f f s la rge cracks were formed t o a distance of severa l hundred f e e t 'from the edge. Many of these cracks were a foot o r even as much as 3 fee t i n width, and small scarps were often present , 4 or 5 f e e t high and 20 o r 30 yards long. The general tendency was f o r everything t o s l i d e i n t o the ocean, but t h i s was not always t rue . Miniature scarps o f more than 6 f e e t were seen with a downthrow upon the nor theas t o r inland side. The Merced beds, as a whole, were badly shaken, and bmke up a l l along the coast sec- t ion .

C 1906 Townley and Allen, 1906 April 25. 3:15 p.m. t * r Landslides along t he c l i f f s on the 1939, coast. p. 135.

[;1 B 1957 Bonil la , 1959 p. 34.

x B 1957 Bonilla, 1959,

Landslides occurred pr inc ipa l ly i n two places: along the sea c l i f f between Mussel Rock and Alemany Boulevard, and along t he shores of Lake Mereed. [See loc. 232.1

Cracks r e su l t i ng from lurching or set t lement o f a r t i f i c i a l f i l l occurred p r i nc ipa l l y along the highways but same occurred i n r e s i - den t i a l s t r e e t s and i n stony a r t i f i c i a l embankments on t he west shore o f Lake Merced. Most of the cracks along the highways were on the downhill s i de , were s t r a i gh t , and e i t h e r pa r a l l e l ed t he cen- t e r l i ne o r trended diagonally toward it . Some, however, were arcuate i n plan. In two places i n Westlake Palisades cracks were associated with small set t lements o f the s t r e e t , sidewalk, and lawns. Small ve r t i c a l movements occurred along some o f these cracks and only horizontal separat ion i n others. Cracks due t o lurching o r set t lement o f f i l l s were seen along the coast h i hway north of Mussel Rock; along Chinese Cemetery Road [lac. 134??; along Juni- per0 Ser ra Boulevard a t the i n t e r s ec t i on with t he cemetery road; in Westlake; and southeast o f the i n t e r s ec t i on o f Skyline Boule- vard and Vlestmoor Avenue. Cracks from landsliding occurred near the tops o f t he scarps of

o ld or new landslides. These cracks were t yp i ca l l y arcuate i n plan, c o m n l y showed small ve r t i c a l movements, and i n most places were on the downhill s ide o f highways. This type of crack was prominent along the coast highway and along the cemetery road. Along several of the northeast- trending s t r e e t s and one northwest-

t rending s t r e e t i n Westlake Palisades the sidewalks and pavement were arched. The arching may have been caused by compression resu l t i ng d i r ec t l y from earthquake waves o r by some secondary e f f ec t , such as downslope mvement of t he pavement and sidewalks. t * * Another unusual type of crack was observed i n t he shoulder of t he

coast highway j u s t south of Woods Gulch. Here t he ground was ir- regular ly fragmented as though an explosion had been set o f f beneath it (photo 1).

C 1906 Lawson and o thers , On the ea s t edge of the h i l l s west o f the Chinese Cemetery and 9- 1908, mile house, a l i n e o f cracks extends f o r a distance of about 1,000 p. 250. yards. These cracks are more than a foo t wide in places , and there

is an apparent downthrow on t he northeast ; i n one place there is a long l i ne o f crusht ear th , such as occurs along the main fault- l ine. Inspection showed t h a t these cracks were caused by a s l i g h t land- s l ide . The l i n e o f crumbled ear th was due t o the ea r t h above it on the h i l l s i d e s l i d ing s l i g h t l y , and t he c rmb l ing represented a l i n e o f buckling of t he c rus t . These cracks are upon the top of a h i l l , a t an elevation of about

400 fee t ; t h e i r general d i r ec t i on i s about N. 40' W. , and p a r a l l e l t o the San Andreas f a u l t , and t he l i n e of h i l l s here has the same general trend.

TABLES 5-9

TABLE 6 . S p e c i f i c descriptions of ground failures in the San Francisco Bay counties region-Continued


135 25 B 1906 Lawson and o thers , Mount OZivet Cemetery (A. C. Lawson). -- Perhaps the best i l l u s t r a - 1908, t i on of an earth-flow caused by a sudden accession of water t o the p. 392, 393 and 394. incoherent materials of a slope, i n consequence o f t he earthquake

shock, is t h a t which occurred i n the upper pa r t of Mount Oliver Cemetery, near Colrna, 9 miles south of San Francisco. The l oca l i t y i s a t the base of the San Bruno scarp, and about 2.75 miles northeast Of the San Andreas f a u l t a t Mussel Rock. The s teep slope of t he scarp i s underlain by hard sandstone of the Franciscan s e r i e s , with but a t h in veneer of s o i l , o r none a t a l l . At the base o f t he scarp i s the gent le slope o f Merced Valley, underlain here by Ple is - tocene and recent sands. The sands, p a r t l y eolian, lap up on the lower flanks of the scarp, and mantle t he t r a ce of the auxi l ia ry f a u l t which follows i t s base. The sands thus vary i n thickness from a f ea the r edge t o an unknown thickness, which it is believed may be as much as a few hundred f e e t a t no grea t distance from the base of the scarp. r e t A t t h e moment of the earthquake there was a sudden outgush o f sand and water a t a point a t the upper end o f t he cemetery, close t o the base of the scarp and qu i t e near, i f not immediately upon, the l i ne of t he buried fau l t - t race . This stream o f sand and water, admixed with the loam o f the slope, flowed rapidly down the course o f a shallow arroyo on a grade of about 1:25 with a depth of from 1 3 f ee t i n its upper p a r t t o about 3 f e e t i n its lower. The f m n t o f the stream s top t abruptly a t a pa in t j u s t beyond t he roadway about ha l f a mile from the origin. The flow was s o rap id t h a t i t car r ied away many small t r e e s ; a wind-mill was wrecked and the heavy concrete blocks which served for i t s foundation were swept down, with o ther d6bris. One of the pumping s t a - t i ons o f the cemetery was demolished by it, and 2 horses weie ear- r i ed off t h e i r f e e t , and were ex t r ica ted afterwards with d i f f i cu l t y . (See p l a t e s 130A, B and 131A.) According t o Mr. M. Jensen, the superintendent o f the cemetery, t he

e n t i r e flow had been accomplished within 3 minutes from the time of the shock, and he was a t its source within 20 minutes a f t e r it occurred. The height of the flow within a few hundred f ee t of i t s source was a t t e s t ed by the mud upon the trunks of some eucalyptus t r e e s near i ts margin. This mud extended up t o 13 fee t above the bottom of the arroyo. This, however, doubtless ind ica tes the height of the f ront of the stream as it pas t t h i s poin t . As t he flow advanced, its surface near i t s source rap id ly dmp t ; and by the time the f ront had reached the roadway the stream was probably no deeper a t its source than a t i ts terminus. Indeed, it seems t o have been somewhat l e s s , as there was a marked tendency for the sand t o p i l e up a t the f ront by reason o f the negative acce lera t ion a t the f m n t due t o loss of water. After the moving mass had come t o r e s t and p a r t i a l l y dr ied out , i t was found t h a t i t had l e f t a s t r e ak o f muddy sand on the bottom of t he arroyo averaging 100 fee t wide and about 3 f e e t thick. Taking t he length of the flow as 900 yards, t h i s gives the t o t a l volume o f t he compacted wet sand as 89,100 cubic yards. The cavity i n the slope caused by the evacua- t i on of t h i s sand and loam was not measured, but was estimated t o have a width of 150 yards, a length of 300 yards i n the d i rec t ion of t he flow, and an average depth o f 2 yards. On t h i s est imate, i t s volume would be about 90,000 cubic yards, which agrees qu i t e closely with t he estimated volume of the material e jec ted . * r r There was no disturbance o f the s o i l on e i t h e r s ide of the

cavity, even i n i t s i m e d i a t e v i c in i t y . On the shoulder t o t he southeast , where t he t r a ce o f the auxi l ia ry f a u l t passes over p rac t i c a l l y bare rock, no evidence of movement was detected on c r i t i c a l examination.

p l a t e 130A p l a t e 1308 p l a t e 131A


TABLE 6.Specific descriptions of ground failures in the San Francisco Bay counties regioiz-Continued

Loca- Fig- Pa i l - Accu- Year of Reference Quotation t i on ure ure ra- earth- NO. No. type cy quake

B 1906 Lawson and others, Northeast of Mount Olivet Cemetery there was an earth-flow i n the 1908, sandy s o i l a t t he base of the San Bruno Mountains. The angle a t p. 249 and 250. which the materials s l i d was hardly more than 10 degrees. The sand

and water forming t h i s s l i d e came out of a hole several hundred fee t long and 150 f ee t wide, flowed down the h i l l severa l hundred yards toward t h e cemetery, c a r r i ed away a p i l e o f lwnber, and knocked the power-house from i t s foundations. The f ront of t he mud- flow p i l ed up i n a bank when it reached t he nearly leve l ground, and danuned up the mass behind it. The ear th was harder severa l weeks l a t e r than it must have been a t t h e time of the flow, but it was still slushy and there iras still a l i t t l e water flowing along the path of the earth-flow, coming from a small spring where t he s l i d e originated.

TABLES S 9

TABLE 6 .Spec i f i c descriptions of ground failures in the Son Francisco Bay counties region-Continued

San F ' c i s c o Bay, Santa CZma VaZZey, and east bay hiZZs

Loca- Fig- Fail- Accu- Year of Reference t i on ure ure ra- earth- NO. No. type cy quake

Quotation

136 A 1906 Lawson and o thers , 1908, + p. 249,

x p l a t e 96A.

A 1906 Lawson and o thers , 1908, p. 243.

+

A 1906 Lawson and others, 1908, p. 249.

B 1906, Lawson and others, 1908,

0 p. 250.

B 1906 Lawson and others, @ 1908,

p. 249.

I n f ront of the Holy Cross railway s t a t i o n (p la te 96A) the t racks of t he main l i n e of t he Southern Pac i f ic were s l i g h t l y bent , but t he l i g h t e r r a i l s of a s i de t rack near by were much more disturbed. Around the s t a t i o n t he ground had s e t t l e d and there were a number of cracks, from 4 t o 6 inches wide, but these were probably due t o t he fac t t ha t t h i s ground had been f i l l e d i n t o get the required grade fo r t racks and t he s t a t i on .

Effect on certain street ra ihays (T. Mallally).-- There does no t seem t o have been any ac tua l shortening of the length of the s t r e e t railways of the United Railroads of San Francisco; but the r a i l s i n one location t rave led about 3 f e e t i n a nor ther ly [southerly?] direction. This location w a s i n the va l ley and was marsh land, beginning a t a point about 100 yards nor th of Holy Cross Cemetery, where the r a i l s par ted , and ending about 1,000 yards nor th [south?] of Holy Cross, where the r a i l s buckled up i n t he a i r . We had t o cut out about 3 f ee t a t t h i s poin t , and add 3 f ee t where it parted a t the o ther end. Of course there w a s a decided movement of the r a i l s a l l along, i n a l a t e r a l d i r ec t i on , which l e f t the t racks out of alinement, but was not enough t o prevent operation of cars. This condition would i nd i ca t e t ha t the f i l l i n the marsh land moved

i n a nor ther ly [southerly?] d i rec t ion about 3 f ee t , but tha t the actual d i s tance along our l i ne has not been appreciably changed.

One hundred fee t west of the Southern Pac i f ic Railroad t rack i s the e l e c t r i c l i n e of the United Railroads between San Mateo and San Francisco. This roadbed was a lso f i l l e d i n considerably fo r the required grade, and w a s not as well s e t t l e d as the Southern Pac i f ic t racks , 50 it suffered more severely. West of the Holy Cross Cemetery, the r a i l s were d i s to r t ed and pulled apar t 3 or 4 inches a t t he j o in t s , due mainly t o the dropping of t he roadbed. Poles were out of t r ue , but no wires were seen broken from tension o r the swaying of t he poles.

On the west bank of a creek, near and p a r a l l e l t o the l i ne of the r a i l r oad southwest o f Holy Cross Cemetery, there was a crack several hundred f e e t long. This was along t he bank near t he creek bed and was an inc ip ien t landslide.

North o f Holy Cross S ta t ion , by a l i t t l e lake west o f the cemetery, there was a la rge landslide along the roadbed of the Southern Pac i f ic Railway. For about 300 f ee t the bed caved and i n one place the west t rack was l e f t suspended i n t he a i r . West of the r a i l r oad there were l a rge cracks i n the newly f i l l e d grounds of the Woodlawn Cemetery.

C 1906 Lawson and o thers , The t rack of the e l e c t r i c tramway l i ne , j u s t south of Baden, shows 1908, evidence of intense disturbance. (See P la te 970.) The roadbed p. 247, which was b u i l t up nearly a l l the way here was cracked pa r a l l e l t o p l a t e 970. the r a i l s . One crack varied from 2 inches t o a foot i n width, and

0 extended about 1,000 f ee t along the f i l l e d - i n xoadbed. For t h i s distance the double t racks were twisted back and for th i n a aig-zag fashion, and up and down t o some extent . One r a i l was bent 2 fee t hor i ionte l ly and 10 inches ve r t i c a l l y . Not a s i ng l e r a i l i n t h i s 1,000 f ee t remained s t r a i gh t o r i n place, but i n no case were the r a i l s detached from the t i e s . Most of the poles supporting the e l e c t r i c wires were thrown out o f l i ne . The t i e s were shoved back and fo r t h and from s ide t o s ide , leaving dean, bare placer where they had s l i d about. [See a l so loc. 141.1 The t racks of the Southern Pac i f ic Railway l i ne , which are p a r a l l e l

t o the e l e c t r i c road i n the v i c i n i t y of Baden Sta t ion , were s l i g h t l y disturbed but not so badly t ha t t r a i n s could not run over them. The Southern Pac i f ic roadbed is much b e t t e r ba l las ted than the e l e c t r i c


TABLE 6 .Spec i f i c descriptions of ground failures in the San Francisco Bay counties region-Continued

San Francisco Bay, Santa C l a r a VaLLey, and east bay hi2Z.s--Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on "re ure ra- earth- No. No. type cy quake

Quotation

l ine , because it is a l d e r and has become more f irmly packed, which i s t he reason t h a t it was not disturbed l i ke t ha t o f t h e e l e c t r i c l i ne . This disturbed por t ion of t he e l e c t r i c l i ne continues about 200 f e e t north of a road by the Baden Sta t ion , u n t i l a cu t i s reached where f i l l i n g up was no longer necessary. The cracks were thus con- f ined t o t he f i l l e d ground.

B 1906 Lawson and o thers , The e l ec t r i c - ca r l i ne t h a t runs t o South San Francisco turns a 1908, r i gh t angle a t Baden, from northwest t o northeast . The r a i l s north- p. 248. west and those northeast o f t he turn were both badly bent . On the

northeast branch the r a i l s were bent i n to a U-shape, t he Sase o f t he U being t o t he northwest with a s ide t h ru s t o f about 2.5 fee t . The r a i l s on the northwest end of the l i n e were bent i n to a V, with t he base o f the V painting northeast , the l a t e r a l displacement being about 1.5 fee t . These are about 60-lb. r a i l s , and a t t he V-shaped bend mentioned t he r a i l s were broken i n three places.

C 1906 Duryea and o thers , Of the three , long, r iveted-iron, pipe l i n e s leading from storage 1907, reservoi rs i n to San Franicsco, the middle one, 36 in . i n diameter, p. 252. leading from San Andreas Reservoir, was f rac tured a t one point only.

This was a t Baden, where t he pipe crossed a piece of marsh land on a wooden t r e s t l e .


1906 Gilbert , Humphrey, Sewell, and Soule, 1907, p. 18.



1906 Ouryea and others, 1907, p. 252.

Ju s t e a s t o f the s t a t i on a t Baden, where a creek crosses the county road, there were cracks i n the f i l l e d s o i l * * . Near Baden t he l i ne had been telescoped 42 inches, shearing o f f

an 8-inch gate valve. The [University Mound] reservoi r i t s e l f was undamaged, yet its three days' supply was rendered useless by the breaks i n the cast- iron d i s t r i bu t i ng mains. [See a l so loc. 140.1

North of San Bruno Point, a t the Southern Pac i f i c tunnel along t he bay shore cut-off, no damage was done, except for t he s l i d ing and s e t t l i n g o f the dkbris i n t he newly f i l l e d area.

The buckling of the t racks of t he South San Francisco car l i ne between t he town [South San Francisco] and San Bruno Point * * * i s s igni f icant o f t he cont ras t i n the i n t ens i t y of t he shock a t the two places. The r a i l s are bent and broken i n a number of p laces , where the t r a ck crosses the marsh between the two places. The difference of i n t ens i t y i s s t r i k i n g when it is taken i n to consid- e ra t ion how close they are together.

One fea ture o f t he destruction of t he bridge and pipe across the San Bruno marsh was t h a t some o f the p ipe was thrown t o the west and some t o t he ea s t as rnuch as four o r f i ve fee t . * * * We re-established by carefu l survey, t he s t r a i g h t l i ne and

grade o f pipe, and found t h a t ne i t he r t he o r i g ina l s t r a i gh t l i n e of t he p i l e s nor the grade o f t h e i r tops had been disturbed by the earthquake. . . * [The break i n t he 44-in. Crystal Springs p ipe l ine] was the most extensive which occurred a t any point about the Bay, save those imnediately on t he f a u l t l i n e * * * . This was a t t he crossing of the San Bruno Marsh, where, for a d is tance of about 2 000 f t . , the pipe was supported upon t r e s t l e bents r e s t i ng on a p i l e foundation. The pipe was pulled apar t a t a number of places, and near ly a l l of it was thrown en t i r e l y o f f the supports on e i t h e r s ide .

TABLES 5-9

TABLE 6.Specific descriptions of ground failures in the Son Francisco Bay counties region-Continued

Srm h n c i s c o Bay, Santa Clara ValLe#, and east bay hills--Continued

'\

Fig- Fail- Accu- Year of Reference Quotation tionl "re "re ra- earth- NO. : NO. type cy quake

A 1906 Gilbert , Humphrey, In company with Herman Schussler, chief engineer o f . t h e Spring Valley Sewell, and Soul& Water Campany, the wr i t e r made a de ta i led examination of t he pr inc ipa l 1907, conduits and reservoirs . On t he San Bruno marsh the 44-inch l i n e t o p. 18. the University Mound reservoir had been thrown o f f t he t r e s t l e f o r a

distance of 1,300 f ee t ; and, while the pipe was r e ad i l y repaired, the t r e s t l e had t o be r ebu i l t , as many of the timbers had ro t ted .

A 1906 Derleth, The Crystal Springs conduit * * i s ruptured i n a number of places, 1906b, but mainly where it crosses the marshes. The worst destruction has p. 551. occurred i n a distance o f about 1,600 f t . , where the pipe crosses. a

marsh between San Bruno and South San Francisco. In t h i s place the pipe r e s t s upon a wooden f loor , supported by p i l e bents. These p i l e s on the average penetrate the mud t o a depth of about 40 f t . . * t h e pipe was a l t e rna t e ly thrown from one s ide t o t he o ther of the t r e s t l e f loor and its box covering was generally smashed.

A 1906 Lawson and others, From South San Francisco t o San Bruno, there is a l i ne of b ig s t e e l 1908, water-mains, supported on a t r e s t l e frame, where it crosses the p. 248. marsh. This l i n e d id not break, but was bent and twisted i n t o S-

shaped figures.

C 1906 S m Jose Me?-, San Bruno. The approaches t o the bridges between San Bruno and M 1906b. South City were sunken, making the bridges d i f f i c u l t of passage.

141 26 B 1906 Lawson and o thers , 1908, p. 247.

M p l a t e 9 7 ~ Q

21( C 1906 Lawson and others, 1908, p. 251.

C 1906 The Chicago Record-Herald, 1906a.

x

Near San Bruno, where the county road crosses,a small strewn, there were numerous cracks i n the ground from 3 t o 10 inches wide, p a r a l l e l t o t he l i ne of t he road, which is N. 25' IV. The road a t t h i s place was b u i l t 8 fee t above the mud f l a t s , so t h a t these cracks are accounted fo r by t he s e t t l i n g of t he f i l l . t * * Pla te 97C i l l u s - t r a t e s the e f fec t of the shock upon the t r a ck of t he e l e c t r i c r a i l - way an the marsh west of San Brmo.

Similar things [settlement] happened t o newly f i l l e d roadbeds along the west edge o f the Santa Clara Valley, near Baden and San Bruno.

Train is Shaken Up. I was on a Southern Pac i f i c t r a i n twenty miles from San Francisco when the shock came. * * * Parther on two grea t f i s su r e s appeared on each s i de of t he t rack where t he ear th had opened. A l i t t l e f u r t he r we saw t h a t the Santa Fe t racks , next t o ours, had sunk out of s i gh t where there was a deep f i l l . [The t r a i n continued t o San Francisco.]

142 C 1906 Lawson and others, At San Mateo Point, which i s on the shore o f San Francisco Bay, 1908, e a s t o f the t o m * r * a l l uv i a l f l a t s around the point showed some

n p. 246. small cracks, and there was a s l i g h t sinking of the ground near the bay.

B 1906 San Francisco Bay 11. Voting on Permit Application No. 9-75. P.pplication of the City Conservation and of San Mateo t o rebui ld an ex i s t i ng dike * * * . The dike i s located Development along a mile s t r e t ch of the Bay shoreline between Coyote Point Comission, Regional Park and San Mateo Creek, i n the City o f San Mateo, San

~ a t e o County. Robert M. Davidsan [should be Robert G. Bezzant], Director of Public

Works for t he City o f San Mateo, s m a r i z e d the applicat ion and exhib i t s . He s a id the dike was constructed before t he turn of the century, suffered a f a i l u r e i n the 1906 earthquake, was r ebu i l t about 1911, has been ra i sed a few times as it s e t t l e d i n t o the mud, and a f t e r World War I1 ce r t a i n sec t ions were replaced t o pro tec t housing behind the dike. [The minutes of the Board of Trustees of the City of S m Mateo between ea. f a l l 1910 and April 17, 1911, confirm the


TABLE 6 .Spee i f i e descriptions of ground failures in the San Francisco Bay counties region--Continued

Smz Frrmcisco Bay, S m t a CZaro Valley, and east bay hills--Continued

Laca- Fig- Fa i l - Accu- Yoar of Reference t ion ure ure ra- earth- No. No. type cy quake

Quotation

construction of dikes f o r mosquito abatement, 3,150 fee t long between Burlingame Avenue and Coyote Point and 7,000 fee t long from Coyote Point south t o San Mateo Creek. However, these minutes do not men- t i on reexis t ing dikes and hence do not confirm a dike f a i l u r e i n 1906.7

143 B 1906 Lawson and o thers , (F. Lane.)--South of Menlo Park and e a s t of the Meyer Place on the 1908, west s ide of San Francisquito Creek, a crack about 1.5 inches wide p. 259. ran for 20 f ee t along the edge o f the county road p a r a l l e l t o and

j u s t above t he creek, showing a half- inch ve r t i c a l displacement, the lower s ide ly ing next t o the creek. This crack appears t o be due t o the s t a r t i n g [s ic ] of the f i l l e d ground of which t he road i s pa r t l y made. * * * Water-pipes along t he road leading from the

:+ reservoi r toward Menlo Park had been pulled apart .

C 1906 Hyde, PIPES DESTROYED BY UNEQUAL SETTLEMENT.--Wherever f i l l e d ground 1906c, existed, set t lement i n grea ter o r l e s s degree took place as t he p. 767. r e s u l t of the temblor. +

Southward, i n t he v i c i n i t y of Pala Alto, where t he e f f ec t s of the earthquake were very pronounced, it is in t e r e s t i ng t o observe t h a t the long 12-in. east- iron pipe, known as the Searsv i l le l i ne , supplying the Leland Stanford, J r . , University, was broken i n three places and i n addit ion received many smaller cracks, p r i nc ipa l l y along the bottom.

144 B 1906 Schussler, Neither the Sunol f i l t e r beds, on the Alameda Creek System, nor 1906, the Sunol Aqueduct and 36-inch p ipe l ine , on the e a s t s ide of the p. 32. bay, nor the four submarine [under San Francisco Bay] pipe l i ne s

were injured; only a s l i p - j o in t , on one of t he two 16-inch shore connections, was pul led apart severa l inches, on the ea s t s ide of the bay t t r .

A 1906 Gilbert , Humphrey, (See the maps, Pls. L V I and LVII.) Some subaqueous pipe l i n e s Sewell, and Soul& crossing the bay seem not t o have been injured. 1907, p. 116.

145 11] C 1906 Lawson and others, People reported new holes formed i n the slough near Caoley's 1908, Landing, but t h e i r statements were not ver i f ied . p. 259.

146 A 1906 Lawson and others, In one case a wind-mill ( a t 6, map No. 221, which had been i n use 'a 1908, for years t o pump water from the well , was no longer found necessary,

p. 260. but the a r t e s i an water was muddy.

147 B 1906 Lawson and others, A t the Yniga Ranch, 3 miles northeast of Mountain View Sta t ion , 'a 1908, there was an a r t e s i an well which had, before the shock, flowed

p. 408 and s l i g h t l y o r not a t a l l , and a wind-mill was used t o r a i s e t he water. x p. 261. After the shock, it was found t h a t the casing had been shoved up 2 f e e t , damaging the pmp. The flow of water was increased, and black sand was brought up. Another well a t t h i s ranch was unaffected. Along t he Jagel Landing road, 2 a r t e s i an wells had increased pressure a f t e r the shock. An old a r t e s i an well f i l l e d with stones had begun t o flow for the f i r s t time i n several years.

148 C 1906 Sal inas Daily Indez, On Alviso slough two rows of t r e e s i n an orchard had par ted of f 1906b. and s l i d i n t o the slough.

TABLES L 9

TABLE @.-Specific descriptwm of ground failures in the Sun Francisco Bay counties region-Continued

Sm Fmncisco Bay , Smta Clam? Vattey, m d east b q hilts--Continued

Loca- Fig- Fail- Accu- Year of Referenee Quotation t i on "re ure ra- earth- No. No. type ey quake

@ C 1906 Taber, 1906,

I p. 315; a l so i n

0 Jordan, 1907, p. 279.

C 1906 Ransome, 1906, p. 294.

A 1906 Weatherbe, 1906, p. 402.

O

27A O C 1906 Lawson and others, 1908, p. 282.

B 1906 Lawson and others, + 1908,

p. 281, p l a t e 1408.

0 278 1

A well near Alviso, a t the head of t he bay, formerly required a wind-mill t o pump the water. At the time of the earthquake the casing was driven 2 fee t out of the ground, wrecking t he pump, and s ince t ha t time the well has been flowing under a heavy pressure. In some of the lowlands small cracks were formed, out of which water issued, bringing up mud and sand.

[Railroad grade subsidence of severa l fee t ] is reported from Alviso, a town a t the south end of San Francisco Bay.

* * * some r a t h e r remarkable demonstrations o f t he earthquake have occurred along the levee paths following the Coyote r i v e r north from the bridge on the road from Milpitas t o Alviso. t * * A t the l o c a l i t y mentioned l a rge f i s su r e s , as much as e ight f e e t wide and of near ly equal depth, have been opened and as p a r t i a l f i l l i n g ensued immedi- a t e l y , they must have been of much grea ter depth when f i r s t formed. In some places the road has been completely p r ec ip i t a t ed i n t o the creek and a t a point about ha l f a mile below the bridge both the banks and the bed of t he stream, including a heavy growth o f willows, have been cut by a s e r i e s of p a r a l l e l cracks and the t r e e s and banks thrown in to the stream, thus forming a p a r t i a l dam.

A l l of these cracks are roughly p a r a l l e l with the stream * * . Simultaneously with the above phenomena, dozens of small geysers or spouting c r a t e r s were formed along t he creek and i n t he adjacent f ie lds . The mouths o f these varied i n diameter from three inches t o about 15 in . , though the ac tua l o r i f i c e s probably do not exceed four o r f i ve inches i n diameter. Mud and water were spouted t o a height of over twenty f ee t , and continued t o flow fo r several days. On some of the miniature c r a t e r s incrus ta t ions of s a l t were depasit- ed. The bridge above-mentioned was sh i f t ed on its concrete supports, t h e two ends moving i n opposite d i rec t ions , and throughout the same 1ocali.ty rows o f t r e e s i n the orchards are s a id t o have been twisted and staggered out of shape.

Cracks l i ke those which were observed i n the ground on the Milpitas-Alvisa road reappeared on both s ides of the Coyote River a t i n t e rva l s a l l the way t o San Jose. Altho they occur i n a general north-south d i rec t ion , it seems probable t ha t t h e i r o r i g in was due t o the unstable condit ion of the a l l uv i a l deposits which underl ie the valley.

From 1,500 t o 2,000 fee t west of the bridge over Coyote Creek, cracks cross the road i n front o f the Boot raneh-house, and several of them occur i n the road leading t o t h a t house. (P la te 1408.) Some of these cracks are about 6 inches wide and have a general bearing of N. 43' W. Immediately a f t e r the earthquake, water flowed fmm some of them and brought up sand, which was heapt up about 6 inches high. The water ceased t o flow a f t e r the second day. Near the dwelling house on t he Boot place, the ground s e t t l e d 11

inches on t he ea s t s ide of the crack. The f i s su r e s pas t under the corner of t he dwelling house and the building was p a r t l y thrown from its foundation. The c e l l a r beneath it was f i l l e d with water t o a depth of from 2 t o 3 fee t . There is a capped a r t e s i an well i n the yard of t h i s house, and about t h i s well i s a pool of water 12 feet across. The west s ide of the pool was l i f t e d 1 foot higher than the east s ide , and f i s h were thrown out o f the pool. A hundred f ee t e a s t the f i ssures pas t under t he barn, and t he ground s e t t l e d on t he west s ide . Water flowed from cracks i n the yard and p i l e d up sand 6 inches high on both sides.



S m Francisco Bay, S a t a Clara Vatleg, mzd east bay hills--Continued

Laca- Fig- Fail- Accu- Year of Reference t i on ure ure ra- earth- No. NO. type cy quake

Quotation

p l a t e 140A

p l a t e 143A

People l iv ing near Coyote Creek s t a t e t ha t the water rose between 2 and 3 f e e t immediately a f t e r t he earthquake; and up t o April 26 the water i n t h i s stream had not returned t o its normal level . A t the brzdge over Coyote Creek, an the Alvisa-hlilpitas road, the concrete abutments were t h ru s t inward toward each o the r about 3 fee t . A p i l e driven i n the middle of the stream, irhich had been cut off below the water-level, was l i f t e d about 2 f e e t and noir r i s e s above the water. About 150 f e e t nor th of t h i s bridge t he banks of t he stream cracked,

the f i ssures running p a r a l l e l with the channel and the land on the creek s ide s l i d ing toward t he stream. (P la te 140A.) West of t h e stream, i n an adjoining f i e l d , water r i s i n g t h ru cracks b u i l t up many c r a t e r l e t s o f sand. (P la te 14312.) Residents of the v i c in i t y s t a t e t ha t t he water rose 3 or 4 inches above the tops o f these c r a t e r l e t s while they were being formed, and t ha t i t ceased t o flow toward the end of the second day a f t e r the earthquake.

In the road running northward along the west s i de of Coyote Creek from the bridge, many la rge cracks opened. Five hundred f e e t nor th of the bridge the cracks were 2.5 f e e t wide and 3 f ee t deep when the place was v i s i t ed Apr i l 26. Far ther north the cracks were very abundant, m s t l y p a r a l l e l with the road, and some were 4 f ee t deep and 3 fee t wide. A quar te r o f a mile north o f t h e bridge, the whole road was shoved eastward i n t o the channel of the creek, and with it a la rge number of willows and cottonwood t r e e s t ha t grew along the banks. Just south of t h i s place the road was broken up badly fo r a distance of 300 f ee t . One a f t h e l a rge s t cracks i n t he road was 5 fee t wide, 6 f e e t deep, and more than 100 f ee t i n length. The bearing of the f i s su r e s a t t h i s place was N. 23O W. For the mast pa r t the pr inc ipa l fea tures were approximately p a r a l l e l with Coyote Creek.

C 1868 Lawson and others, Where the Milpitas road crosses Coyote River, t he banks were shaken 1908, together and the river-bed f i l l e d up. p. 446.

C 1868 Lawson and others, Milpitas.--Along Coyote Creek the ground was cracked from Boot's 1908, ranch t o the San Francisco Bay, t he cracks being on the bay s ide

0 p. 444. and following the winding of the creek. As i n 1906 much water was e jec ted from the cracks, and Coyote Creek rose. (W. Bellou.)

B 1906 Lawson and others, Of the two bridges over Coyote Creek, the northern one suffered + 1908, some damage by displacement o f end supports. I t was unsafe t o p. 280. t r ave l over a t the time o f t he v i s i t . The southern bridge [loc.

1541 was found i n t a c t , the end supports showing signs of but small movement.

0 C 1906 Carey, Near Milpitas along the Coyote Creek a r t e s i an water gushed out of 1906, cracks and hales i n the ground, making temporary fountains several p. 297. fee t high, bringing up silt and forming cones about t he ou t l e t , as

shown i n photograph. Similar outpourings of water are reported from the Salinas valley. In some cases a r t e s i an wells stopped flowing, but i n general the water l eve l w a s ra i sed , so t h a t many ordinary wells overflowed. The water i n most cases was more o r l e s s muddy.

150 B 1906 Lawson and others, At Mrs. North Whitcomb's ranch, on the south s i de of the Alviso- 1908, Milpitas road, between Coyote Creek and Milpitas, the prune orchard

4 p. 281. was cracked and t he ground sh i f ted a t several places. The ranch- house, o f concrete with a wooden upper s tory , was cracked across

bt the northwest comer and s e t t l e d s l i g h t l y on t he northwest side. In the back yard were f i s su r e s 1 foot wide, running about N. 13a W. , with a dawnthrow o f 1 foot on the e a s t s ide. Some o f t he prune t r e e s i n the orchard are 2 f e e t ou t of alignment, and some as much as 6 feet . The l a t e r a l displacement here shows a r e l a t i v e mvernent

0 of the south s i de toward the ea s t . Considerable sand was brought up by water flowing fmin t he cracks i n t h i s orchard.

TABLES 5-9

TABLE 6 .Spec i f i c descriptions of ground failures in the San Francisco Bay counties region-Continued

S m Fmncisco B a y , S m t a C h VaZZey, and east bay hiZZs--Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t ion "re "re ra- earth- No. No. type cy quake

151 0 C 1868 Lawson and others, Cracks i n the v i c in i t y o f Milpitas flowed a r t e s i an water f o r 48 1908, hours a f t e r the shock. (Mr. Durkee.) p. 444.

C 1906 Jordan, i ~ i c t u r e caption] s l u rp i n so f t Ground, ~ i l p i t a s . 1907,

C 1906 Smr Jose HeraZd, The d i s t r i c t between Milpitas and Alviso is seamed with immense 0 1906b. f i s s u k s from which water i s pouring. The country i s being rapidly

inundated. The road between Milpitas and Alviso i s beneath water CP i n many p laces , making passage impossible. The bridge over the

I creek i s down. Sections of land varying fmm small p l o t s t o e n t i r e f i e l d s have sunk t o depths o f s i x inches t o f i ve fee t .

152 C 1906 Lawsan and others, MiZpitos-San Jose Road (G. F. Zoffman).--About 0.5 mile south of 1908, Milpitas, on the Milpitas-San Jose road, cracks were formed acmss p. 282. the road. They did not , however, appear t o have any de f i n i t e direc-

t ion , and were so small t ha t no l a t e r a l movement was discernible.

C 1906 The Evening Post, The roads s k i r t i n g the bay were s l i g h t l y in jured i n places by 1906a. f i ssures , but no serious f a u l t i n s o f the underlyinr rock was ob- - . -

served. * * r

Fmm San Jose t o Alviso the road i s lowered i n places by the shocks, and the front of t he p r i nc ipa l ho te l a t Alvisa has sunk a t l e a s t ten feet .

153 0 C 1868 Lawson and others, I was t o l d a t the time t h a t the water spurted up i n the s t r e e t s of 1908, San Jose, and out i n the road between Milpitas and San Jose, t o t he p. 444. height of several fee t .

154 A 1906 Lairson and others, On the north s ide of t he bridge which crosses Coyote River, on the 1908, San Jose-Milpitas road, some cracks were found but they were evi-

0 p. 282. dently caused by the s l i d ing o f the banks. The bridge was not damaged.

155 B 1906 Lawson and others, (M. Connel1.)--On the farm of Mr. Fox, 3 miles nor th o f San Jose, @ 1908, t h e water pipe of an a r t e s i an well was broken o f f 60 f e e t below the + p. 286. surface and car r ied by the heave of the land i n a northwesterly

d i rec t ion 4 f e e t from i t s or ig ina l posit ion.

156 c 1906 Lawson and others, AZm Rock Rood (G. F. Zoffman).-- + * * No cracks were found 1908, between Coyote Creek and the mountains r * * . p. 282.

157 C 1906 Jordan, San Jos;'s water works, l i k e t h a t o f Santa Rosa, was not in jured; 1907, its sewers a l so were l e f t i n t a c t , showing t h a t there was no unequal p. 188. displacement of the ground.

C 1906 Lawson and others, (E. C. Jones.)--There was only one broken gas main i n San Jose, 1908, caused by t he high wall o f t he building f a l l i n g over; the bricks p. 285. penetrated t h ru the so f t ear th t o the main and broke it.

158 C 1906 Lawson and others, Water and mud i n many instances are reported as having spurted @ 1908, from the a r t e s i an wells , but i n a few days they resumed t h e i r normal

0. 284. condition. * * * Data.were obtained of the d i rec t ions i n which the chimneys f e l l

thmout t he town. After the da t a were col lec ted and tabulated as shown below [2710 chimneys], it became evident t ha t c h i k e y s usua l ly f e l l with the s l a n t of the roofs.


TABLE G.Spee i@ descriptions of ground failures in the San Francisco Bay counties region-Continued

Srm Francisco Bay, Srmta Clara Valley, mzd east bay hills--Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t ion "re "re ra- earth- No. No. type cy quake

~ ~

1865. October 8. The streams a t McCartysville and Los Gatos have r i s en grea t ly since t he earthquake, tapping t he sources of the a r t e s i an wells i n the Santa Clara Valley, many of which have ceased t o run since the earthquake.

159 B 1906 Law~on and others, J w t northwest of the 12-mile house, where the county road crosses • 1908, t o t he Fisher ranch, there were cracks from 2 t o 6 inches wide i n

p. 286. the coarse gravelly bottom of the Coyote River. There was evidence of water having been e jec ted from these cracks, as there were heaps

0 of clean, f i ne material surrounding small o r i f i c e s . I t was s a id a t the ranch-home t h a t muddy water came out of these openings following the shock.

160 C 1906 Lawson and o thers , Along the road down Penetencia Creek, a considerable amount of 1908, dcbris had s l i d i n to the road, i n many places obstructing a l l t r a v e l p. 283. except f o r pedestr ians; but no evidence o f cracks could be found.

161 C 1906 Lawson and others, Between t h i s place [Calaveras Valley] and t he head of Alum Rock • 1908, Canyon, the res idents s t a t ed t ha t cracks appeared across the road

p. 282. i n severa l places; but a l t ho t h i s was i n the proximity of the Calaveras Valley fau l t - l ine , which passes t h ru t h i s region, it was not possible t o ver i fy t h e i r statements.

162 C 1906 Ouryea and others, Between Niles and San Jos6, on the Southern Pac i f ic , there was a t + 1907, one point a displacement of 3 f t . horizontal , but the v e r t i c a l dis- p. 258. placement was only 6 in .

163 C 1868 Lawson and others, On the mountain above the old Mission, j u s t above a place ca l l ed 1908, Peacock Springs, a great crack i n the ear th appeared, which lookt p. 444. as i f t he lower p a r t o f the mountain had parted and s l i p t down.

Many times I have cros t the bridge which was b u i l t over the crack, and s t op t and t h r o w rocks down t o see i f I could t e l l how deep it was. (Mrs. N. Ainsworth.)

164 B 1906 Lawson and others, According t o the track-boss, t he r a i l r oad t rack suffered no d is - 1908, placements anywhere between Niles and Irvington. p. 304.

165 A 1906 Lawson and others, While at Niles, a v i s i t was made t o one o f the new tunnels of the 1908, Western Pac i f ic Railway, which i s about 1 mile e a s t of Niles i n the p. 306. Niles Canyon. The tunnel had penetrated about 130 f ee t i n t o the

h i l l s i d e , but had not yet passed t h ru anything but a sandy clay During the previous winter the walls a t the po r t a l , and a l so on the inside, had stood without timbering. Since the earthquake i t had been impossible t o break out more than 4 fee t of ground ahead of the timber sets without caving taking place. There had been an apparent movement i n t he s o i l which had removed i t s consistency and made i t incoherent. The amount of water present i n the tunnel was perceptibly changed. The foreman s a id t h a t there was more water s ince the shock than there had been even i n the wet tes t pa r t of the winter.

C 1933 Coffman, 1933. M a y 16. Niles Canyon * * * Landslide * * 1973, p. 169.

TABLES 5-9 117

TABLE G.-Speci/ic descriptions of ground failures in the San Francisco Bay counties region-Continued

San Frnncisco Bay, Santa C k a Vattey, m d east bay hit&--Continued

Loca- Fig- Fa i l - Accu- Year o f Reference Quotation t i a n "re ure ra- earth- No. No. type cy quake

166 B 1906 Lawson and others, A t t h e Alviso ranch, a l i t t l e over .a ,mi le north o f t he t o m 1908, [~ivermore], the top of a small h i l l was broken up a t t he time of p. 309, t he earthquake. The breaking of the ground did not cons is t of f i s su r - p l a t e 141A. ing along a l ine , but was i n t he nature o f an up l i f t of a l imited area.

There were 3 f a i r l y well marked concentric r ings where the ground had broken, t he ins ide r i ng i n each case being forced higher than t he outside r ing. The ef fec t was s imi l a r t o t h a t obtained by placing three p l a t e s of different s i z e s within each other.

* M r . S t i l l repor t s t h a t where the ground was deformed i n con- c en t r i c r idges, as described by M r . Matthes and Mr. Crandall, there was an a lka l i ne spring years ago. so so new hat s im i l a r phenomenon was seen on Cahi l l ' s r idge [locs. 116, 120) i n San Mateo County.]

1906 Lawson and o thers , 1908, p. 308, P l a t e 141A.


1861 Holden, 1898, p. 58.

1861 Coffman, 1973, p. 157.


1906 OokZmd Tribune, 1906a.

An i n t e r e s t i ng feature appears 0.25 mile north o f Meyn's ranch, west of the road leading north from Livermore, about 2 miles north of t h a t place. I t i s on the s u m i t of a smoothly rounded h i l l , s loping gently down t a an even, peaty meadow t raversed by t he a rmyo of Cayetana Creek. * * + The summit of the h i l l i n question was found crowned by a s e r i e s of concentric deformations, r i s i n g stepwise above one another. A number of nearly concentric cracks were found extending northward i n to a s o r t of panhandle, along each of which an upward movement of t he s o i l had apparently taken place. The u p l i f t along the 2 pr inc i - pa l cracks was found t o be 19 and 16 inches, respectively. Along the minor cracks the ve r t i c a l displacement amomred t o an inch o r txro only. The surface o f each s t ep o r bench was found t o slope inward, and i n some places the edge even appeared t o have curled inward.

S a t 4 R i t a , 3 miles e a s t of Dublin (F. E. Matthe$).--A small, f l a t levee along t he ea s t bank o f Tassajara Creek, immediately north of the main road, showed several somewhat c rescent ic cracks along which the gmund had s l i p t down and toward t he creek from 1 t o 3 inches. These cracks extended f a r t he r south, according t o loca l s e t t l e r s , and cros t the road; but t h i s was no longer t raceable a t the time of the v i s i t .

1861. Ju ly 4?; 16h. I l m . r- * * i n t he San Ramon Valley * * * . It opened a la rge f i s su r e i n the ear th , and a ne* spr ing of water.

1861. Juty 3. Contra Costa and Alameda Counties. Severe r r * In San Ramon Valley a f i s su r e opened, and a new spring of water appeared.

The t rack suffered a s l i g h t s h i f t i n g i n several places north of t he v i l l age [Newark]. Cracks opened i n the ground i n the v i c in i t y of 2 small watercourses, but on a l e s s extensive sca le than tha t noted a t Alvarada [loc. 1701. Some o f them cros t the r a i l r oad track. In every case they emitted t he same blu ish sand [with t he water) tha t had been found near the Alameda Sugar Mill. In one place, 1.5 miles northeast of the v i l l age , considerable water was still l e f t standing i n shallow ponds. According t o neighboring ranchmen, these ponds had not existed p r i o r t o the earthquake.

Newark, April 18.--About a mile nor th of t h i s t o m a f i s su r e was opened by t he earthquake. This f i s su r e i s about a mile and a ha l f i n length and from e ight t o twelve inches i n width. From the f i s s u r e quant i t ies of water are being emitted, although the

land is i n what might be termed a dry d i s t r i c t .


TABLE 6 .Spec i f i e descriptions of ground failures in the Son Francisco Bay counties region-Continued

Son haneisco Bay, Smta C h Vottey, and east boy hitts--Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on "re ure ra- earth- No. NO. type cy quake

Quotation

0 C 1906 The BuZZetin, F i s s u ? ~ ~ l i ~ a t ~ d by earthquake near Newark becomes running water, and pipe we115 become gushers spout ing twelve f ee t . One of the m s t pecul ia r freaks of t he great temblor of l a s t Wednesday

m r n i n e i s a f i s su r e in t he ear th a shor t d i s tance from Newark. several ~~ ~

f e e t wrde and about a mile and a h a l f l o n e . running with an excellent -. - qual i ty of water. This r iver was first noted by t he crew of one of t he Southern Pac i f i c

Company's t r a i n s coming up fmm San Jose, and inves t iga t ion discloses t h a t many of t he o ld pipe wells i n the v i c in i t y have suddenly gushed for th , i n some instances t he water spouting from e ight to , twelve f e e t i n to the a i r .

1906 Lairson and others, The [Alameda Sugar] m i l l s tands on f l a t , a l l u v i a l ground 100 f ee t 1908, north o f Alameda Creek. Along t he banks of the l a t t e r a large number p. 305. of cracks extend, roughly pa r a l l e l with the stream. Considerable

masses next t o the stream-bed slumped toward the same, leaving gaping cracks 1 t o 2 f e e t wide, and carrying with them small outlying buildings, notably t he f ire-engine house, which moved bodily, concrete foundation and a l l , 2 f e e t south toward the creek. A small r a i l r oad t r e s t l e southwest of the m i l l moved 4 inches south on both of its abutments, pmbably owing t o slumping o f loose ground on the north s ide of the creek. A 2-inch water-pipe, l a i d under the ground some 60 fee t north of t he creek and almost p a r a l l e l with the same, shoivs indications of having been submitted f i r s t t o tension, causing rup- t u r e a t one of the j o in t s , then t o sudden compression, causing it t o be jamned together with violence.

Cracks i n the ground may be found as f a r as 250 f e e t from the creek. They were near ly a l l closed a t the time of t he v i s i t (May 7) , but were ea s i l y t raced by t he s t reaks of bluish-gray sand which has issued from them, toge ther with considerable quan t i t i e s o f water. According t o t he Chinese cook o f the superintendent, t he cracks nearest t o h i s dwelling opened and closed severa l times i n succession during the quake; and la rge volmes of aud-laden water gushed from them, splashing up some 10 f e e t i n the a i r a t each closing. A l a rge crack o f t h i s kind opened under t he northwest comer of the dwelling and t he superintendent est imates t h a t f u l l y 500 gallons o f water gushed from it, the flow continuing with decreasing volume fo r about an hour. The fence i n f ront o f the house shows t h a t t he ground there has been r a i s ed i n to a low hump. The sewer pipe leading west t o the creek was detached from the house by a space o f 22 inches. * * *

In t he roadway south o f t he m i l l , water oozed out i n a number o f places, without the production of v i s i b l e cracks. The water pipes and hydrants i n t h i s v i c in i t y were crusht i n several places.

* * A few cracks opened across t h e s t r e e t s [of Alvarado], but these had been f i l l e d on t he date of the v i s i t .

0 C 1868 Lawson and o thers , ALuarado. * * The ground opened i n several places and water issued. 1908, p. 443.

B 1906 Duryea and others, A t Alvarado, near the pmping s t a t i on , t he 30-in. r iveted-iron force 1907, main conducting t he water t o Oakland crosses the Alameda Creek on a p. 254. shor t bridge. + * i In t h i s pipe was placed a 24-in. s top-gate r e s t -

ing an a concrete foundation. The p i l e s under the pipe were not deeply M placed; and the shake opemted t o s e t t l e them i r r egu l a r l y , some going

down as much as 6 in .

ALVARADO FORCE MAIN.-- * + r The earthquake threw t h i s pipe out o f alignment i n to a decidedly sinuous location fo r a distance of about one-half mile. The flanges o f the ga te valve were broken by t he unequal set t lement of t he t r e s t l e s carrying t he pipe and t he concrete p i e r on which t he valve res t s .

TABLES 5-9

TABLE 6 . S p e c i f i c descriptions ofground failures in the San Francisco Bay counties region-Continued

Sun Francisco Bay, Srmta ' ~ t a r a Vattey, and east bay hilts--Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t i a n "re "re ra- earth- NO. No. type cy quake

B 1906 Derleth, The Alvarada force main, a r ive ted pipe, was wrenched i n two places. 1906a, Three hundred f e e t from the pumps t he pipe snapped, and a quarter p. 503. of a mile fur ther on toward t he c i t y , i n which d is tance t he pipe l i e s

upon p i l ing , the f lange of a la rge ga te valve was broken by the M s e t t l i n g of the p i l e s .

B 1906 Duryea and others, I A ~ the pumping s ta t ion] on t he marsh land near t he Bay shore, one 1907,

X mile west of Alvarado. + *

p. 249 and * - * the foundation s e t t l e d about 2 f t . , breaking a l l the pipe p. 250. connections. During the quake t he channel of the creek disappeared,

i t s bottom being ra i sed t o the general level of the adjoining land.

171 0 B 1868 Lawson and others, The ground opened from 6 inches t o 2 f e e t , and water with sand was 1908, ejected t o a height of from 1 t o 3 f e e t . North o f the v i l l age p. 443. [~ayward] a r idge o f ground 3 f ee t wide was ra i sed 2 f ee t . * *

On the h i l l s there were several new springs.

0 B 1868 LawSon and o thers , The crack below Hapards Hotel was 12 inches wide. I t ejected

1908, water and white sand. A fence which t raversed a h i l l from north t o p. 442. south was m o s t by t he crack, and had t he ends o f the boards loosened

from the posts . Gradually these boards l a p t over one another, u n t i l within a couple of weeks they overlapt several inches, the progress of t he overlapping being noted from time t o time by a pencil mark. The "cap" board of the fence was a lso a rcht up i n consequence of t h i s movement. Large waves were s e t up i n the s o i l . The house'was moved southward, while a neighbor's was t i p t northward. (D. S. Malley.)

0 C 1868 Lawson and o thers , On B S t r ee t the ground opened about 2 inches, and water and sand 1908, were forced from the opening. Some springs were closed, while others p. 442. were opened o r made t o flow more f ree ly .

C 1868 Lawson and o thers , I n the v i c i n i t y o f Hapards it i s reported t h a t there were two 1908, branch cracks fmm the main one [fault?] , t rending o f f i n to the h i l l s .

0 p. 435. Water and sand were ejected from the crack i n one place.

172 U C 1838 Wood, Allen, 1838, l a t e i n June. * VIII a t l e a s t . * * * Landslide a t San and Heck, Leandro. 1939, p. 3.

C 1868 Halley, 1876, p. 263.

El 0

B 1868 Halley, 1876, p. 267.

The bed o f the San Leandro creek, which had been dry fo r severa l months, i s now coursed by a stream of water s i n f e e t wide and one foot deep. Back o f San Leandro, i n the mountains, there are numerous f i s su r e s i n the ear th , fram which came clouds of dust , and fram some have come great volumes o f water which flows i n to t he San Leandra Creek.

A Mr. Davis, who res ides on a farm near Sa" Leandro, informs t he But te t in t ha t t he workmen on h i s farm a t the time the shock occurred, observed t h a t t he ground was disturbed and thrown about with a rap id and violent ro ta ry motion, which continued several seconds. A creek running through the farm, and which was nearly dry, rose i n s t an t l y t o the depth of about three f ee t , and severa l deep gulches were famed i n the p la in .

173 X B 1906 Lawson and others, * * * a t M i l l s College * * * In the made ground there was a drop 1908, p. 304. o f from 1 foot t o several f e e t .

C 1906 AZmneda Daity Argus, [At Alameda] * * * damaged t racks i n t he marsh. 1906. One of t he new t racks of t he Oakland Traction Company across Webster

S t . sunk about four f e e t and t he r a i l s are twisted, blocking t r a f f i c .


TABLE 6 ,Spee i f i c descriptions of ground foilures in the San Francisco Bay counties region-Continued

San RvlnciscD Bay, Smta Clara Valley, and east bay hills--Continued

Loea- Fig- Fail- Accu- Year of Reference Quotation t i on ute "re ra- earth- NO. No. type cy quake

174 c 1906 Derleth, The [water] d i s t r ibu t ion system o f East Oakland seems t o be prac- 1906a, t i c a l l y unaffected, but i n West Oakland, upon f i l l e d ground, some p. 503. o f t he smaller pipes and some of t he serv ice connections have been

broken, but the damage i s , r e l a t i v e l y speaking, s l i g h t .

C 1906 Almnedn Daity Argus, Bay Faxm Island shows many crevices and cracks on t he surface. 1906.

C 1906 The Evening Post, Railroads are inac t ive , and wires are useless. Railroad t racks 1906b. across the marsh are twisted. . * . More than 600 feet of the

I t rack of t he Oakland Trans i t Comapny sank nearly four f e e t .

B 1906 Duryea and others, One 12-in. cast- iron pipe near t he water f ront i n East Oakland was 1907, drawn apar t a t the j o in t , and one o r two breakages occurred on a p. 254. long l i n e of 8-in. pipe leading t o the Southern Pac i f i c Railroad

Broad-Gauge Pier .

B 1868 Holden, 1868. October 21; I X . Oakland. * * * The draw of t he ra i l road 6 1898, bridge was thrown twelve inches out o f l i ne .

p. 76 and 77.

B 1906 Oakland Enquire?, The mgnes i t e works a t t he foot of Ninth avenue i n East Oakland have X 1906. sunk several f e e t and now t he ground on which they stood i s under

water. The sinking i s probably due t o the v io len t earthquake of Wednesday morning. The land on which the works stand i s very unsub- s t a n t i a l , being simply b u i l t up by the process o f dredging.

A 1906 Derleth, 19068, p. 503.

1( A 1906 Lawson and o thers , 1908, p. 302.

A 1906 Oakland TAbune, 1906b.

[Picture caption] Frame s t r uc tu r e which was cracked and wrenched and which sank for several f e e t i n to the yawning ground.

The drawbridge on the l i ne of the S. F. and 0. R. R. was thmwn out of place about e ight inches, and as the locomotive and near ly a l l t h e cars were a t San Antonio, no t r a i n l e f t Oakland a t 8 o'clock.

The earthquake d id not produce, r e l a t i v e l y speaking, much destruc- t i on t o these [Oakland, Alameda, and Berkeley water systems] works. Breaks i n the pipe l i ne s invar iab ly were found upan s o f t ground, o r where the pipe l i ne s passed from so f t and y ie ld ing t o more r i g i d foundation. * The 24-in. s t e e l pipe crossing the Twelfth S t . dam a t Lake Merri t t was a l so snapped from the s e t t l i n g of the f lood gates, but the 37 1/2-in. pipe running p a r a l l e l and s l i g h t l y t o the eas t , across the same s o f t foundation bed was only s l i g h t l y deformed.

On t he Twelfth S t r e e t dam, a cast- iron pipe was broken and displaced over a foot; while the high pressure s t e e l pipe pa r a l l e l i ng it was p rac t i c a l l y undisturbed.

Menaced by Water. The t i d e a t the time of the earthquake was a t i t s loivest, and a t the time o f wr i t ing it has turned and running i n t o Lake Merri t t . What w i l l happen when the lake is f i l l e d and t he back- ina of the water Dressures with e rea t force on t h i s oort ion of the darn i s something :hat can not beUforetold. The rock foundation of the dam a t t h i s point is cracked and broken

and gives ind ica t ions of giving away a t any time. REPAIRS DAMAGE Secretary Hanson of the Contra Costa Water Company

was ear lv on t he scene and with a force of men besan a t once t o - ~~ - ~ ~ -~~~ ~ ~~~-~ ~

r e ~ a i r the water main so t ha t the ~ e o e l e o f t he c i t y could have water . - fo; the pro tec t ion of t h e i r homes i n case o f f i r e . '

I t i s not expected t ha t water w i l l be turned on before t h i s afternoon The great main has sunken with the s t r e e t and broken i n two and parted

for the space of several inches and t he pipe w i l l have t o be uncovered and a new length put i n o r the pipe drawn together.

TABLES S 9 121

TABLE 6 . S p e c i f i c descriptions of ground failures in the San Francisco Bay counties region-Continued

San Francisco Bay, Santa C h a Valley, and e a s t bay hills--Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i o n "re ure ra- earth- No. No. type cy quake

Quotation

- -

Along the west shore of Lake Merri t t the bank has been cracked and broken and caved o f f i n to the lake, showing t he force o f the shake a t the water leve l .

176 C 1906 Ouryea and others, A 24-in. r ive ted pipe ly ing i n a s t r e e t leading acmss a t i d e marsh * M

1907, i n Oakland was pulled apar t 5 in. and displaced 8 i n . l a t e r a l l y by p. 254. the s e t t l i n g of the e n t i r e s t r e e t .

c 1906 Rickard, r r * t h e lower a l l uv i a l f l a t s o f Oakland and Berkeley were ser ious ly 1906a, disturbed * r . p. 271.

B 1868 wood, M.w., October 21, 1868. [Oakland] Port ions of t he wharves were car r ied 1883, away i n some instances, while walls were cracked i n almost every p. 665. house * * * .

177 A 1906 Bmnson, Southampton Shoals Lighthouse i n northern Sen Francisco Bay s i t s 1959, firmly on p i l e s t ha t were t i l t e d eleven degrees o f f ve r t i c a l during p. 185. the quake and never r ighted.

178 C 1906 Sat inas D d l y Indes, The Santa F e n s Condition. Santa Fe o f f i c i a l s repor t t ha t t h e i r l i ne 1906~ . a t Point Richmond had suffered grea t ly from the temblor. * * * A.

landslide choked tunnel No. 2 near Point Richmond but t h i s was cleared by 6 o'clock. * * * All water mains i n Richmond and Paint Richmond were broken.

B 1906 Lawson and others, 1908, p. 391, p l a t e 128A, p l a t e 1288.

Sun P a b b e m t h - s t q . - - A t t he time of the earthquake a landslide occurred on Mills ' ranch, which i s about 4 miles e a s t of San Pablo. The s l i d e i s i n t e r e s t i ng from the f ac t t ha t a previous geological mapping of the region indica ted t h a t t he point where i t occurred was on the l i ne of a f a u l t extending i n a nor ther ly and southerly direc- t i on through t he Sobrante H i l l s . The s l i d e was examined by Mr. E. S. Larsen, who describes it as f o l l o ~ s :

There are many other lands l ides i n t h i s v i c in i t y , showing t ha t the coiuitry i s subject t o such s l i de s . In t h i s pa r t i cu l a r case, one of the Castro bays informed me t h a t the main p a r t of t h i s s l i d e began during the winter ra ins , and had f a l l en a foot o r more during these ra ins . The balance of the f a l l occurred the morning of the earthquake. The s l i d e i s an t he ea s t s lope of a steep h i l l s i d e and extends from the top of the h i l l nearly t o the bottom, about 400 f e e t on the slope. The width i s about 1,500 f e e t . A t the northeast corner t he scarp is grea tes t , reaching perhaps 50 f ee t . I t gradually decreases, and is very s l i g h t for t he southwest 700 fee t . On t h i s southwest 700 f e e t t he only evidence of a s l i d e i s the crack near the top of the h i l l . The nor th 800 f ee t of ground shows every evidence of s l id ing . The dry ground i s much cracked, and these cracks extend up and down the h i l l near the scarp and along the h i l l where the gmund has been p i l ed up. I n some places there is a network o f cracks. On the south s ide of the main s l i d e the ground has p i l ed up about 10 feet . This extends along near ly a l l of t he south s ide , and t h i s tendency t o p i l e up t o the south i s shown i n o ther places. Moreover, the north s i de shows t h a t the ground has pulled away toward the south. The above shows t h a t the movement was not d i r ec t l y down the h i l l , but was mare t o the south. The formatiah is sandstones and sha les , with considerable so f t surface so i l .

The same s l i d e was subsequently v i s i t ed by M r . F. E. Matthes, and t he following descr ip t ive note i s by him. (See f igs . 68 and 69.) [See f igs. 68 and 69 a t end of tab les . ]


TABLE 6.Speeif ie descriptions of ground failures in the San Francisco Bay counties region-Continued

S m Francisco Boy, S a t a Clara VoZZey, mid east boy hitls--Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on ure ure a - earth- No. No. type cy quake

Quotation

The s l i p occurred ea s t o f a high r idge a t the southern end of the Sobrante H i l l s . It covers the northeast ha l f of an area whose te r raced nature i s ind ica t ive of a former lands l ide o f much l a rge r dimensions. The accompanying sketches show the general ou t l ines , and a cmss-sec t ion of the s l i de . I t w i l l be noticed t ha t the s l i d e does not extend a l l the way down the slope, i t s lower edges being f u l l y 100 fee t o r more above the bottom of the gulch. The lower slopes were not mater ia l ly changed, and but l i t t l e dgbris f e l l i n to the stream-bed. A steep scarp has been produced ea s t of the c r e s t of the r idge.

The dawnslip along t h i s scarp does not exceed 50 f ee t , and decreases both t o north and south. Along the north edge there has been a marked movement down and southward, the scarp there averaging 10 f ee t . Along t he south s ide , on the o the r hand, t he loosened mass had advanced over the o ld surface, presenting a bulging and cracked f ron t a l scarp some 6 f ee t high. I t appears from t h i s t h a t t he movement took place, not along the l i n e o f grea tes t dec l iv i ty , but in a d i rec t ion somewhat more southward, a5 ind ica ted by the arrow. The 2 hummocks probably ex is ted before the s l i p occurred, but judging by t h e i r grea t ly cracked and ren t sur faces , it seems l i k e l y t ha t t h e i r height has been s l i g h t l y increased. The main crack, which extends southward fmin the upper scarp, continues along the h i l l s i d e i n i r r egu l a r zig-zags f o r some 300 f ee t south o f t he s l ide . (See p l a t e 128A, 8.)

180 B 1906 Lawson and others, On a h i l l s i d e above Peach Tree Spring, on the west s ide of Mount 1908, Diablo and very near the contact of the Knoxville shales and t he p. 310. Franciscan, a crack opened i n the gmund about 30 f e e t long, i n a

north and south d i rec t ion , gaping 4.5 inches.

C 1965 Coffman, 1965. September 10. r * Minor racks l ides were observed a t Mount 1973, Diablo * . p. 182.

181 A 1906 Satinos DaiZy IndexX The b ig bridge a t Middle River between Point Richmond and Stockton + 1906~. sank three f ee t and was shoved out o f l i ne .

182 B 1906 #m York l%lbune, Stocton, Cal., April 18, -- * + The Santa Fe bridge, over the x 1906. San Joaquin River, s e t t l e d several inches. [See a l so loc. 254.1

B 1906 The Evening Post, Santa Fe Bridge Over the San Joaquin Se t t l e s . Stocton, Cal.,

X 1906d. April 18.- A sharp earthquake shock was f e l t here a t 5:15 o'cloek

t h i ~ mrning. The Santa Fe bridge over t he San Joaquin River s e t t l e d several inches.

C 1906 Lawson and others, At Point Reyes Light-house * * * . One of the light-house keepers 1908, s t a t e d t ha t a f t e r the shock he laokt from the window o f h i s mom, p. 195. which connnanded a port ion of the sea near the beach, and saw t h e

water "boiling," but there was no change of the nature of a wave.

184 C 1906 Lawson and others, About 6 miles f a r t he r south, a t the head of Pine Gulch Creek, another 1908, mad crosses the range, and i n following t h i s a group of cracks was p. 75. seen. A shor t distance west of the divide, and about a mile i n a

d i r e c t l i ne fmm the fau l t - t race , is a fault-sag trending northwest- southeast. On each s ide of i t a crack was seen, the eas te rn crack being the wider and showing a small throw t o the southwest. This crack was t raced for about 0.75 mile and found t o curve t h ru an arc of near ly 90' from southeast t o southwest. A t i t s southwest end, o r a t

TABLES 5-9 123 TABLE 6 .Spec i f i c descriptions of ground failures in the Son Francisco Bay counties region-Continued

San Fmneisco Bay, Santa C h o VaZtey, and east bay hitts--Continued

Laca- Fig- Fail- Accu- Year of Reference Quotation t i o n ure "re ra- earth- No. NO. type cy quake

l e a s t the southwestern l i m i t o f t racing, it i s on a r idge, and it there expands in to , o r e l s e is replaced by, a group of cracks diverging fan-wise. On each member of the group fau l t ing took place, the dawnthrow being toward t he northwest except i n t he case of two apparently shor t cracks with downthrow t o the southeast . On four of these cracks t he throw was grea ter than 1 foot , and a t one place it was about 5 fee t . Each crack was associated with a preexis ten t bluff o r scarp, ind ica t ing tha t e a r l i c r mavements have occurred a t t h e . . same place. The f i e l d i n which the pr inc ipa l phenomena occur i s cu l t iva ted with the exception of the s teeper scarps, whose faces

p l a t e 52A r e t a i n a bushy gmwth. (See p l a t e s 52A and 53A.) p l a t e 53A A t r a c t lying between t h i s l o c a l i t y and t he coas t , and extending

Several miles i n each d i r ec t i on , exhib i t s a pecul ia r topography i n t e r - mediate i n type between t ha t of the R i f t and t h a t commonly associated with landslides. Near the coast are a number of basins with ponds o r lakes o f much l a rge r s i z e than those along the R i f t , and i n asso- c ia t ion with these are seen a number o f sags s imi la r t o the f a u l t sags of the Ri f t . On several l i ne s which were thought from the physiography t o represent part ings between d is loca ted blocks, earthquake cracks were seen, and on one o f these near the coast there was a ve r t i c a l displacement o f 3 f e e t , the downthrow being t o the southwest.

B 1906 Schlocker and Vert ical movement of as much as 5 f e e t , which Gilbert ( in Lawson and Bonilla, others, 1908, p. 75) ascribed t o fau l t ing , occurred a t l o c a l i t y 3 south 1963, of Mud Lake. The authors accompanied by Alan Galloway and Don Tocher, p. 31. were able t o pos i t ive ly i den t i f y l oca l i t y 3 as the one t ha t Gilbert

described (op. c i t . , 1908, p. 75). This movement was probably caused by lands l id ing r a t h e r than fau l t ing . Very l a rge landslides are pmmi- nent j u s t west of the l oca l i t y , and study of a e r i a l photographs revea ls t ha t an i r r egu l a r scarp formed by a lands l ide joins the f rac tures described by Gilbert (1908). Moreover, the stream valley down h i l l from the s i t e has been blocked by the landslide movement, causing ponding of the va l ley and deposit ion of sediments.

185 C 1906 Lawson and others, Seven Lakes.-- r t There were a few landslides, and a number of 1908, cracks already mentioned (page 75) [loc. 2621 t e s t i f i e d t o movements p. 195. of large blocks of ground: but I think there were due t o a pecul ia r ly

s ens i t i ve condition of the country ra ther than t o the violence of the shock.

186 B 1906 Lawson and others, Daniel Bondietti l i v e s 3.5 miles north fmm the head of the [Bolinas] 1908, lagoon, and h i s buildings are about 20 rods e a s t of the main crack.

0 p. 192. His house was sh i f t ed 3 fee t toward the f a u l t and h i s barn moved i n the same di rec t ion .

187 B 1906 Lawson and others, Back of the S tee le place, near the north end of t he [ ~ o i i n a s ] 1908, lagoon, the h i l l s i d e s t a r t e d [ s ic ] eastward toward the lagoon, p. 198. bulged upward, and cracked i n t o several f i s su r e s from 30 t o 100 feet

long and fmm 5 t o 18 inches wide. * r r The two b lu f f s along t he stage road from the head of the lagoon t o the town a lso broke and f e l l from 40 t o 60 f ee t , completely blocking t he s tage road along t he lagoon beach.

C 1906 Lawson and others, [picture caption] Cracks made by earthquake i n t i d a l mud near head 1908, of Bolinas Lagoon. G.K.G.

55 p l a t e 498.

C 1906 Lawson and others, [picture caption] Earthquake cracks i n Bolinas a t edge of an earth- 1908, quake sag. G.K.G.

56 p l a t e 528.


TABLE 6.Specific descriptions of ground failures in the Son Francisco Bay counties region-Continued

srm hwzcisco Bay, Smta Clara valley, and eost bay hitts--Continued

Loca- Fig- Fa i l - Accu- Year of Reference t ion "re ure ra- earth- No. No. t r pe cy quake

Quotation

1906 Gilbert , G. K., [Picture caption] Gilbert co l lec t ion n2895. Cal i forn ia earthquake. (from USGS Library &use one mile northwest o f Bolinas. Stands on a l l u v i a l fan of Archives). Bolinas Creek. Was mved southward on fan. In t he foreground is a

secondaly crack. Marin County, California. n.d.

1906 Lawson and others, The great ocean b lu f f s along the south and west o f the entrance t o Bolinas Lagoon, some 165 f ee t high, crumbled and f e l l , crashing down upon the ocean beach and reducing t he alope of t he bluff t o ha l f i t s former angle.

1906 Lawsan and others, On the s ea - c l i f f s on the north s i de of Bolinas Bay and west of the 1908, town of Bolinas, there was a very general c r a b l i n g and f a l l of the p. 387. s ea - c l i f f upon the beach.

1906 Weatherbe, 1906, p. 402.

* * * the mouth o f BolinaS bay * * * the high c l i f f s -- about 150 f t . -- a t the end of the peninsula have crumbled and f a l l en down, carrying small t r e e s with them.

1906 Lawson and o thers , Along t he main s t r e e t of Bolinas stand mast of t he houses * * r . 1908, Of these about two-thirds were heaved, s l i d , t i p t , and sha t te red i n t o p. 198. uninhabitable condition. * t * Along t he bay shore were 7 buildings.

Of these 6 went over o r dorvn. At the Plagg S t a f f Inn the t ipping of the house has thrown it so f a r e a s t i n t o the bay t h a t one may s i t along the upper edge o f the pa r l o r f l oo r and f i s h i n 4 fee t o f water along the opposite edge of the same room.

1906 Neatherbe, At the v i l l age o f Bolinas, t he s o i l has sl ipped down ea s t e r l y toward 1906, the lagoon and on the ea s t s ide of the road, which runs north and p. 402. south, the buildings are en t i r e l y demolished, while those f a r t h e r up

the h i l l on the west s ide are n o t . s o badly affected.

1906 Lawson and others, On the s teep southern face of Mount Tamalpais a number o f rocks were 1908, loosened and r o l l e d down the slope, some o f them being la rge enough p. 77. t o cut swaths t h r u the th icke t which were v i s i b l e f o r months afterward.

1906 Lawson and others, At t he bui ld ing occupied by M r . George D. Shearer, 306-310 Fourth 1908, S t r ee t , an level land near the depot, there is a crack running north p. 207. and south * * * .

1906 Lawson and others, A crack one block long, north and south, i n low land near the s t a t i on 1908, i s reported. p. 207.

1906 Lawson and others, A crack was formed i n the ground 100 fee t long, running north and 1908, south. The grea tes t damage was ha l f a block north o f t he depot. p. 208.

1906 Lawson and others, At Scheutien Park, 1.5 miles east-southeast of San Rafael, on land 1908, 7 fee t above sea-level * * water-pipes were broken, and there were p. 208. many small f i s su r e s i n the neighboring ground, running north and south.

1906 Let te r by William [William Hancock was l i v ing i n Sausa l i to and working i n San Francisco Wancock, 1906 After the earthquake he went down t o the fe r ry i n Sausali to.] earthquake collee- The asphalt pavement i n f ront of the f e r ry was a l l broken up and in t ion ; California one place sunk down, and the sea frontage looked as though it was His tor ica l Society about t o f a l l i n to t he water; long l i ne s of cracks p a r a l l e l t o t he Library, San sea edge. Francisco.

TABLES 6 9

TABLE 7 .Spec i f i e descriptions of ground failures in San Francisco City and County

Location number i s assigned t o each reported ground-failure s i t e . Corresponding numbers are found on p l a t e 3. Figure number r e f e r s t o f igure i n t h i s repor t showing damage described under "Quotation" column. Fa i lure type i s indicated by the following symbols. Corresponding symbols are found on p l a t e 3.

Hi l l s ide landslides including ro ta t iona l slumps, 0 Sand bo i l s block g l ides , debris avalanches, and rockfa l l s

Absence of ground f a i l u r e noted 0 Streambank landslides including ro ta t iona l slumps

and s o i l f a l l s Miscellaneous e f f ec t s

+ Lateral spread X Cracks i n s t r e e t s and p ipe l ine breaks

X Gmund settlement 0 Arrows showing extent o f area affected. Symbol shows f a i l u r e type

Gmund cracks not c l e a r l y associated with land- s l i de s , l a t e r a l spreads, set t lement o r primary f a u l t movements

Accuracy with which f a i l u r e s i r e s can be located i s given as fallows: A, a s i t e t ha t can be accurately relocated; 8, a s i t e t ha t can be relocated t o within a few kilometers and probably could be located more accurately with fu r t he r inves- t iga t ion; C, a s i t e where the information i s insuf f ic ien t t o allow prec ise location.

P la te numbers i n the "Reference" column r e f e r t o p l a t e s i n t he o r i g ina l murce material .

Laca- Fig- Fa i l - Accu- Year of Reference Quotation t i on "re ure =a- earth- No. No. type ey quake

193 31 X C 1906 Lawson and others, [foot of Market ground f a i l u r e zone] In spots the s t r e e t s sank 1908, bodily, cer ta in ly as much as 2 f ee t , probably more. Accompanying p. 233. t h i s depression, concrete basement f loors were broken and arched,

as i f t o compensate f o r it. The surface of the ground was deformed i n t o waves and small open f i s su r e s were formed, espec ia l ly close t o the wharves. Buildings on the water s ide , along East S t r ee t , + generally slumped seaward, i n some cases as much as 2 f ee t . The damage was grea tes t close t o the water 's edge, growing l e s s as t he so l i d land was approached, gradually a t f i r s t , then more rapidly. These ohenamena seem t o sueeest t h a t the materials used i n f i l l i n g

UP A 1906 Hyde, 1906b, p. 739.

+ A 1906 Jordan, 1907, p. 125.

+ A 1906 Derleth, 1906b, p. 553.

C 1906 Jordan, 1907, p. 98.

. ~~~~

~~ - -" were shaken toge ther so as t o occupy l e s s space with the accompanying development of waves, f i s su r e s , and s t r uc tu r a l damage.

[Picture caption] The f i r s t p i c tu r e shows t he d i s t o r t i on of car tracks and the l i n e of the l oca l f au l r i n East S t . a t its junction with Pac i f i c S t . , along the water f ront . This t e r r i t o r y i s within the a r e a o f made land on the marshes of the o ld harbor front .

[Picture caption] Fig. 12--Rupture of Car Tracks and Pavement on East S t ree t , Corner of Pac i f i c S t ree t .

Fig. 14 shows destruction of car r a i l s and s t r e e t surface, corner East and Pac i f i c S ts . , near the Ferry Building.

I t i s a general observation t h a t the earthquake waves t ransmitted by the s o f t e r and l e s s coherent materials and formations appeared t o be much more des t ruc t ive than waves which traversed t he hard and more e l a s t i c rocks and o ther sound deposits . The bil loir- l ike e f f ec t s t h a t appeared i n the s t r e e t s o f San Francisco near the Ferry house are most excellent examples of deformations i n so f t , incoherent materials. The s l i d ing and r o l l i n g e f f ec t s observed on some of the sand dunes and espec ia l ly along the h i l l s i d e a t the nor them end of Van Ness Avenue may be c i t ed as a l l i e d phenomena. [ loc. 2211


TABLE 7 .Spee i f i e descriptions of gmund failures in San Francisco City and County-Continued -- -

Loca- Fig- Fa i l - Accu- Year of Reference t ion ure ure ra- earth- No. No. type cy quake

A 1906 Lawson and o thers , 1908, p. 143.

C 1906 S e a t t l e Post- IfiteZZigencer, 1906b.

A 1906 Hall, 1906, p. 32.

Quotation

Edi tor ' s note: A p a r t of the following quoted t ab l e was deleted, as it toas not per t inent t o the discussion.

TabZe 6.--Elevations of bench-marks before and a f t e r the earthquake

LOCALITY BENCH-MARK

[Picture caption] EARTHQUAKE EFFECT. A f i s su r e on East S t r ee t near the water front . Note t he sett:ement of the s t r e e t surface as shown by the enposed curb a t the r i g h t hand s ide . I n t h i s l oca l i t y the ground was "made," o r a r t i f i c a l l y f i l l e d in.

Water Front Suffered Less. * * North of the f e r ry things were not SO good, but s t i l l they were b e t t e r than anyone enpected. Broadway wharf No. 1 was badly l i s t e d , and w i l l have t o be r e b u i l t , while Broadway No. 2 collapsed completely. The Union s t r e e t wharf was blown up by t he mi l i t a ry au tho r i t i e s t o save other property.

Here are, i n general terms, the leading f a c t s o f earthquake ef fec t within the area which we may designate as t he c i t y ' s pr inc ipa l so f t spot , even though it i s not the l a rge s t area of marsh and mud f l a t which has been f i l l e d over and b u i l t upon.

Beginning on the e a s t and west s t r e e t s a t the north l i m i t of the area of disturbance, we f ind the uppermost evidence on Pac i f ic s t r e e t a t about t he corner o f Front, then on Jackson s t r e e t a t about the i n t e r - sec t ion of Battery; next on Washington s t r e e t a t the in te rsec t ion of Battery; next on Clay near the in te rsec t ion o f Sansome; then on Sacramento, a l so a t t he in te rsec t ion of Sansome; on California it i s doubtful whether the disturbance a t Sansome is due t o general subsidence or only t o subsidence toward a foundation excavation; on Pine s t r e e t t he upper l i m i t o f pronounced s t r e e t disturbance is about 100 f ee t above Battery, on Market the l i ne i s very d i s t i n c t a t about the foot of Bush s t r e e t . On Mission a sharp l i ne o f subsidence across the s t r e e t about 100 f e e t before F i r s t , on Howard and i n the l i n e of Fremont t o the ea s t thereof t he l i n e is again p l a in ly marked by a crack and subsidence below it; and f i na l l y , on the l i n e of Folsom, about seventy f e e t below Beale, a l i n e o f subsidence i s very d i s t i n c t l y marked diagonally across t h e s t r e e t exactly a t t he location and i n the d i rec t ion of the foot of the old hard ground and edge of t he former mud f l a t . P l a t t i ng these poin ts on t he map it i s found t ha t they e i t h e r l i e within o r ou t l i ne very near ly t he l i m i t o f the former s o f t spot i n t he lower port ion o f the pr inc ipa l b u s i n e s s p a r t of t he c i ty . Below t h i s bounding l i ne the s t r e e t s are near ly a l l waved, there

being depressions of from s i x inches t o as much as four f e e t i n one

TABLES 5-9 127

TABLE 1 .Spec i f i c descriptions of ground failures in Sun Francisco City and County-Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t i on ure "re ra- earth- No. No. type cy quake

o r two places and two or three fee? a t qu i t e a number of points . While it cannot be s a id t ha t the whole s t r e e t area within t h i s zone has sunk, a considerable port ion of it has, and near the riater f ront most of it ha5 sunk from s i x t o twelve inches, with several areas of grea ter depression. Davis s t r e e t from Vallejo t o California s t r e e t , presents perhaps the

extreme case, there being d i s t i n c t depressions of from one t o three f ee t a t every s t r e e t c ross ine o r within everv block. but it i s

B 1906 Derleth, e 1906a,

p. 503.

apparent t h a i some of t h i s i; due t o s l i p o f the st;eet f i l l i n g i n to building foundation areas, consequent upon f a i l u r e of re ta in ing walls and poor foundations of the buildings themselves. The area of about eighty f ee t frontage which has sunk t o a maximum

of about eighteen inches i n f ronr of rhe Market-street Ferry bui ld ing and the depression of soinetrhat grea ter area and t o a maximum depth of about three f ee t , a t the northwest corner of the same building, are the extreme cases of subsidence along the main warerfront. Contrasted with t he very heavy masonry Ferry building founded on p i l e s and toll-

Crete, which has not sunk a t a l l , these subsidences w i l l i l l u s t r a t B the point t h a t it is only the so f t mud and loose f i l l i n g thereon which has been disturbed by t he earthquake. There are places on the norrh and south s t r e e t s where the whole s t r e e t appears t o have been t h r o w a few inches toward t he bay, and a t East street, which i s the waterfront s t r e e t , there is much evidence of s imi la r movement t o about s i x t o eighteen inches where the pavement has been shoved against wharves, p i e r s and o ther vater-front s t r uc tu r e s and caused t o buckle up.

S t r ee t and water-front railway r a i l s are i n a number of places buckled up s i x inches t o two f e e t o r are thrown as much a s . s i x inches out o f l i ne . Throughout the f i l l e d area above s t r e e t - co rne r . s i l t basins have been tr ipped out o f plwnb and bulged i n to sidewalk areas, and sewer manholes i n s t r e e t in te rsec t ions +re i n several places canted up, showing sewer disturbance beneath; while granire curbs f o r 100 f ee t or more i n length were t r ipped up by unequal movement o f s t r e e t pavements and t he underlying ground and thrown out bodily on t h e i r s ides upon the pavement or sidewalk. The Market-street Railway t rack , car r ied on a prism of concrete

founded on p i l e s f o r its length within t h i s urea, did not sink with the s t r e e t on each s ide of it and i s ye t nearly on i t s or ig ina l grsde except a t one point , where it has sunk apparently about four inches fo r several hundred f ee t . I t is noticeable t h a t s t r e e t s have sunk l e a s t o r not at a l l i n f ront

of the newer deep-piled foundations fo r adjacent buildings--Market s t r e e t i n f ront of t he Hotel Terminus and i n f ront o f the Buckley building, f o r instance--and t h i s ind ica tes t h a t a p a r t of t he s t r e e t movements i s due t o set t lements i n t o c e l l a r and foundation excavations on f a i l u r e of t h e i r r e t a i n ing walls .

A curious reve la t ion is noticed on the west s ide of Davis s t r e e t , between Broadway and Pac i f ic s t r e e t . Here i n 1857 was the water-front wharf. IVhen the s t r e e t was f i l l e d i n it is evident t h a t a l l the p i l e s were not removed. The s t r e e t pavement, which i s basa l t blocks, has sunk s ix inches o r more fo r the f u l l length of t he frontage, and t he posit ion of the p i l e heads fo r about ha l f the length i s marked by t h e i r punching the pavement up i n l i t t l e pyramids, and fo r the o ther ha l f length the pos i t ion oE the p i l e bents with caps on is shown by the pavement sinking on e i t h e r s ide of the caps, leaving r idges of paving blocks aver them. Evidences of o ld s t ruc tures beneath the surface and f i l l i n g are brought out i n a s imi la r way a t a number of points .

A l l of the made ground between the Market St . water f ront and the region of Montgomery S t . has been decidedly moved and deformed. Wave- l i k e e f f ec t s are c o m n along lower Market S t . and the water front . Wave-like depressions and c r e s t s amounting t o foui. and f i ve f ee t are found throughout t h i s region. The same observations can be made i n many other l o c a l i t i e s of the c i t y , where s o f t ground is met.


TABLE 7.Specific descriptions of ground failures in Son Francisco City and Connty-Continued

Loca- Fig- Fail- Aceu- Year of Reference t i on "re "re ra- earth- NO. NO. type cy quake

Quotation

The earthquake destruction was most marked on s o f t and sandy s o i l and upon made ground. The Ferry building, a t t he foot of Market St . i s decidedly damaged. I t s tower must be taken down. Bad cracks are found running hor izonta l ly between the windows on the second story. This building r e s t s upon excellent foundations, but it i s supported upon material which seems t o have acted l i ke a viscous f l u id . The building has been unharmed by f i r e , and with t he exception of t he tower can be repaired.

A 1906 Gilbert , Humphrey, The Union Ferry Building [on p i l e s ] (PI. X L V I , A), with the exception Sewell, and Soul6, of i t s high tower, was l i t t l e injured, and t he l eve l of i t s f loors was 1907, not perceptibly changed. A t t h e same time, the s t r e e t s a t i t s f ront , p. 135. which res ted simply on t he made s o i l , were m l l e d i n to waves 3 or

4 f e e t i n height.

U N I O N FERRY BUILDING. * * * The s t r e e t sur face a t the N. W. corner s e t t l e d Z ' , cracking the asphalt pavement and carrying down a la rge sec t ion of the sidewalk.

1906 Duryea and others, 1907, p. 319.

On Market S t r ee t , near the Ferry House, the cable t racks r e s t i ng upon p i l e s moved very l i t t l e i n comparison with the collapse of the s t r e e t surface an both s ides of the car tracks.

1906 Jordan, 1907, p. 123.

[Picture caption] Fig. l l - -S t ree t Surface i n Front of the Ferry Tower, Shoiring Undulations and Cracks i n t he Asphalt Pavement.

[Picture caption] Fig. 15.--Crack i n Pavement i n Front of Ferry Building. Figs. 14 and 15. Views o f S t r ee t Deformations, San Francisco Earthquake.


* * + t h e cable-car system on lower Market S t r ee t . On account of the constant tendency o f the whole d i s t r i c t t o subside from year t o year, as t he f i l l i n g material became more c lose ly compacted, these conduits were constructed upon p i l i n g t o secure permanence of grade. On both s ides o f them the s t r e e t sank i n places as much as 2 f e e t , and the pavement was broken, f i ssured , and thmwn i n t o waves. These t racks did not escape en t i r e l y , but f o r severa l days, before s t r e e t r epa i r s were made, they cons t i tu ted a narrow ra i sed path along the center of t he s t r e e t .

1906 Hyde, 1906b, p. 739.

The most important wave-like d i s t o r t i ons were observed on lower Market and Mission S t s . , and on East St . [loc. 1931 along the present water f ront .

1906 Rickard, 1906a, p. 271.

I n San Francisco the s t r e e t - ca r t racks-on Market s t r e e t re ta ined t h e i r alignment f a i r l y well , but the roadway was depressed f u l l y four fee t . . Market S t r ee t i s paved with cobbles; where there was an asphalt pavement i n the lower pa r t s of t he town below Montgomery s t r e e t , the roadway was buckled so as t o make t en t s , and i n o ther spots there were depressions several f e e t below the normal level .

[Picture caption] Mark of the Earthquake's force an East s t r e e t .

1906 Los Angetes DaiZy rimes, 1906a.

[Picture caption] The procession t o the San Francisco Ferry. Railroad t racks torn by earthquake.

1906 The Evening Post, 1906~ .

Down on the harbor f r on t , the e a r t h seems t o have sunk fmm s i n t o e ight inches, and great cracks appear i n the s t r e e t s . Car t racks were twis ted i n t o a l l shapes * t * .

TABLES E-9 129

TABLE 7.Speeif ic descriptions of ground failures in San Francisco City and County-Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t i on "re ure ra- earth- No. No. type cy quake

196 A 1906 Gilbert , Hmphrey, AETNA (YOUNG, OR COMMISSARY) BUILDING. The steel-frame s t r uc tu r e a t Sewell, and Soul$, the corner of Spear and Market s t r e e t s , + * r e s t s upon p i l e s , and 1907, suffered r e l a t i ve ly small damage from the earthquake. PI. XXV, A,

I P. 76, shows t he corner of the building and the subsidence o f the s t r e e t a t p l a t e 25A. t h i s point . * There was a vault under the Market s t r e e t sidewalk,

imed i a t e ly behind the wall a t the curb l i ne . The basement f l oo r in t h i s vault was of concrete and had s t o t a l thickness o f 7 o r 8 inches. The earthquake caused the ear th t o bulge up i n the port ion of t h e , basement under the sidewalk, rupturing the concrete f l oo r and turning it up on i ts edge, so t h a t \rhere.there had previously been a Clear headroom of 7 1/2 f ee t the highest point of the bulge was within 3 1/2 f ee t of the beams carrying the sidewalk.

A 1906 Gilbert , Hmphrey, The f ive-story AEtna Building * * * was b u i l t on p i l e s . r * * The Sewell, and Soulk, basement f loor , which was o f concrete 7 or 8 inches th ick , was pushed 1907, up under the sidewalk, reducing the headmom a t t h i s point from 8 p. 31 and 32. f e e t t o 3 112 f ee t , appmximately. This bulging was probably caused

by s e t t l i n g (PI. XXV, A), as the foundation p i l i n g did not extend under the sidewalk. [PI. 25A shows sidewalk did not subside; adjacent s t r e e t did.]

A 1906 Himelwright , YOUNG o r SELLER BUILDING. S.W. COT. Spear and Market S t ree ts . 1906, * * + Levels on t he water t ab l e show tha t the N. E. and S. W. corners

x p. 81 and 84. are 3" and 6" lower respec t ive ly than the N. W. corner. These f a c t s would indica te t h a t the foundations had moved su f f i c i en t l y t o tilt the e n t i r e building t o the ea s t . From marks on the curb o f the sidewalk, it i s a l so apparent t h a t the surface o f the ground s e t t l e d considerably around the N. E. corner.

A 1906 Lawson and others, 1908, p. 244.

A 1906 Lawson and o thers , n 1908,

p. 236.

B 1868 Huber, 1930, p. 266.

B 1868 Huber, 1930, p. 268.

[Picture caption] Surface of Market S t r ee t sunk by the earthquake f i ve f e e t below the curb leve l .

Appraiser's Bui2ding.-- * + The northwest corner i s 0.909 foot = 10.908 inches above the southwest corner. The nor theas t corner is 0.909 foot + 0.054 = 0.963 foot = 11.556 inches above the southwest corner. . The southeast corner is 0.080 foot = 0.96 inch above the southwest corner. The rod was held on top o f the water-table a t each of the four corners, and the s i gh t s were nearly equal i n length. The south s ide of the building is about 11.23 inches loirer than the north side. [Because no immediately pre-earthquake measurements are ava i l - able, i t is not cer ta in tha t a l l set t lement occurred during the earthquake. 1

Buildings erected upon good foundations withstood the ordeal well, even when the s t r e e t s around them were deprest and f issured. The Appraisers' Building furnishes a good i l l u s t r a t i o n of t h i s ; it i s subs tan t ia l ly b u i l t of br ick upon a p i l i n g foundation, a t the corner of lvashington and Sansame S t r ee t s , and s t i l l s tands without s i gn i f i - cant damage. The l eve l s of i t s foundation walls were not disturbed.

The shock was pr inc ipa l ly f e l t on "made ground" and the f l a t s where the foundation i s knaiqn t o be unre l iab le a t a l l times. Eastward of Montgomery S t r ee t , toward the Bay, there are a number of buildings injured, while some are u t t e r l y ruined. Along the old water l i ne of the Bay, running j u s t back o f Macondray's o ld place on the corner of Pine and Sansome S t r ee t s , and thence diagonally north-eastward toward the corner of Front and Jackson S t r ee t s , something l i ke a s l i d e occurred and buildings suffered severely from the s l ipp ing of the made- ground foundations on the old mud bottom of t he Bay. This e f f e c t i s more marked a t some points than others; a t the o ld Railroad Hotel on Clay S t r ee t , below Sansome, it i s more marked than elsewhere.

* * photographs of i * * the rear of the Railroad House, on Clay S t r ee t , between Battery and Front, as they appeared a f t e r the shock.


TABLE 7 .Spec i f i c descriptions of ground failares in San Francisco City and County-Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on ure urn ra- earth- No. No, type cy quake

Quotation

Lairson and others, 1908, p. 436.

On Pine S t r ee t , near Battely, the cobbles on the south s ide of the s t r e e t sank away from the curbstones t o t he depth of 1 foot i n some places; and the asphalt sidewalk on the north s ide was twisted and torn out o f a l l shape, and i t s connection with the curb-stone severed.


In many places t he made land s e t t l ed . A t t h e junction of Market and Front S t r ee t s , the ground sank fo r a foot or two, and there was evidence t ha t t he t i d e had r i s en i n the adjoining l o t a t the same t i n e , f o r a pond of water co l lec ted and remained u n t i l law t ide .


Himmelwright, 1906, p. 86 and 89.

A t the comer of F i r s t and Market S t r ee t s , the ground open'ed i n a f i s s u r e several inches wide. At o the r places t he ground opened and water was forced above the surface.

CROCKER ESTATE BUILDING. S. E. Cor. hlission and F i r s t S t r ee t s . * * * The l eve l s on the water t ab l e show t h a t the N. LV. corner and t he N. E . corner are 1/2" and 1 1/2" lower, respec t ive ly , than t he S. E. corner of t he building.


A t Fremont and Mission S t r ee t s the ground opened i n many places. The general course of damage i n the c i t y was along the i r r egu l a r l i ne of the "made land," o r low a l l uv i a l s o i l , where i t met t he hard o r rocky base beneath it. Along the l i ne of the o ld shore of Yerba Buena Cove, we found t he damage t o brick buildings much the la rges t .

The f loor of the Pac i f ic foundry was ra i sed about 2 fee t i n places. The center of Mission S t r ee t (opposite Fremont S t r ee t ) exposed an opening from 8 t o 10 inches wide; and openings of the ground were a lso p l a in ly t o be seen on Fremont S t r e e t , i n the same v i c in i t y . Outside o f the i m e d i a t e d i s t r i c t described above, damage t o the

r e s t of t he c i t y was very meager. r + t h e region of grea tes t ag i ta t ion was confined t o t he law port ions of t he c i t y , o r t he v i c i - n i t y of some old creek bed o r swamp.

Lawson and others, 1908, p. 437, p l a t e 146.

Huber, 1930, p. 267.

Himmelwright, 1906, p. 86.

Huber, 1930, p. 264.

The shop of Mr. Garrat t , brass folmder, near the corner of Mission and Fremont S t r ee t s , has been r a i s ed t o its o r ig ina l pos i t ion . I t was found t o have been lowered about e ight inches by t he recent earthquake.

SCOTT BUILDING. S. W. Cor. Fremont and Mission S t r ee t s . * * The S. W . corner of the building i s badly racked and cracked by t he earthquake.

Staddardts warehouse on Beale S t r e e t is sa id t o have been thrown out of place several inches as though it had been l i f t e d up and s e t down again, while the south s ide of the building appears t o have s e t t l e d considerably. After t he shack, the water rushed i n to the ce l l a r , or basement, but whether from a disarrangement of the water pipes, o r from any f i s su r e i n t he ear th which might have opened, was not known.

Louderback, 1947, p. 52.

Mr. Spear infamed me t ha t during t he earthquake of June, '38, before mentioned, a la rge sand-hi l l s tanding i n the v i c i n i t y of what i s now Frernont s t r e e t . between Howard and Folsam. and between which and the bay a t high t i h e there was a space of a b o k twenty f ee t , permitt ing a f ree passage along the shore t o Rincon Paint ( the coves of which were then much resor ted t o f o r picnics and mussel pa r t i e s ) , was moved bodily close t o t he water, so as t o obs t ruc t t he passage along the shore. After t h a t no one could pass there a t high t i d e , and we were compelled t o go amund back of the sand-hil l , and wade thmugh loose sand t o reach t h a t point , a much mre laborious walk.

The Fol je r [ s ic ] Building, on Howard S t r ee t , was of br ick ex t e r i o r and wood i n t e r i o r , and was l e f t s tanding a f t e r the earthquake, the f i r e not having reached it. As was generally the case i n buildings of any


TABLES 6 9 131

TABLE 7 .Spec i f i c descriptions of ground failures in San Franckco City and County-Continued

Loca- Fig- Fail- Accu- Year of , Reference Quotation t i on "re "re ra- earth- No. No. type cy quake

descript ion, the chimneys suffered and a small port ion o f the parapet wall, but othenuise the building was not damaged; and ye t , a t t h i s

2( very s i t e , the s t r e e t i n front of the building had s e t t l e d about 2 f t .

A 1906 Himmelwright, FOLGER BUILDING. S. W. Cor. Howard and Spear Streets . * * * The X 1906, s t r e e t leve l s e t t l e d about 2 f t . a t t he northeast corner of the

p. 28. building, but there are no earthquake cracks v i s i b l e i n the walls a t t h i s point .

The baseule bridge recent ly e rec ted by the Southern Pac i f ic Company across the San Francisco River, so-called, a t t he foot of Channel St . , near the water f ront , was ser ious ly crippled by t he set t lement, t o the extent of 4 i n . , o e a s t comer of the south abutment.

C 1906 Lawson and others, [south of Market zone.] kigh i n t e n s i t y was developed thruout a 1908, i small elongate d i s t r i c t having a width o f about two blocks, which p. 236, 237, extends from near the comer of Eighth and Mission S t r ee t s t o the and 238, v i c in i t y of Fourth and Brannan S t r ee t s ; from t h i s point t he boundaries map 17. are i r r egu l a r and very sinuous, leading t o the water-front a t about

the cmss ings of Third S t r ee t with Berry and Channel S t ree ts . A glance a t the geological Map, No. 17, shows t ha t the regular ly bounded port ion of t h i s d i s t r i c t corresponds very closely with the area of a former tide-marsh, drained and flooded by one o r two small t i d a l streams. The former shore l i n e of Mission Bay was j u s t north of Brannan St r ee t , between Fourth and F i f t h S t r ee t s , $0 t h a t the irregu- l a r seaward port ion o f the d i s t r i c t l i e s outs ide the o ld shore. This i s one of two l o c a l i t i e s i n t he c i t y , the o the r being-a "made"

land t r a c t along t he former course o f Mission Creek [loc. 2141, i n which des t ruc t ive e f f ec t s of great magnitude were conspicuously developed. Only i n very close proximity t o the f a u l t was grea ter violence manifested. For blocks the land surface, paved s t r e e t s , and building p lo t s a l ike , were thrown in to wave forms, trending ea s t and west about p a r a l l e l t o the length of the area. The amplitude and wave-length of these ear th bi l lows, and t he distances t o which they extend, are i nde f in i t e and i r r egu l a r . The f i s su r i ng and slumping, and the buckling of block and asphalt pavements i n t o l i t t l e an t i c l i ne s and synclines (arches and hollows), accompanied by small open cracks i n the ear th , characterize the land surface. This s lmp ing movement o r flow took place i n the d i rec t ion o f the length of the area, and its amount was grea tgs t near-the,center, o r channel, where the s t r e e t l ine5 were sh i f t ed eastward out of t h e i r former s t r a i gh t courses, by \ mounts varying from 3 t o 6 f e e t . A s a t i s f ac to ry photograph of t h i s phenomenon was noth,obtainable, owing t o the quick convergence of pa r a l l e l l ines i n perspective, b5t t o the observer i n the f i e l d it was a very s t r i k ing r e i i i l t o f ?.he shock. The grea ter p a r t of the d i s t r i c t iras occupied by wooden dwellings

and shops, with a small percentage of mediocre brick buildings and a few of subs tan t ia l construction. The f i r e swept the area c lear . Not even heaps of d6bris remained t o cover the ground, mast of the des t ruc t ive e f f ec t s beina obl i te ra ted , along with the s t ruc tures i n which they were developed. Enough remained;however. Foundation walls and sidewalk pavements were broken and flexed; sharp l i t t l e an t i c l i ne s were produced i n the s t r e e t by the arching of block paving,

late 88C a5 on Russ S t r ee t between Folsom and HowardStreets I ~ l a t e 88C): grani te curbing was broken and t h ru s t up i n t o an inverted V, as on

p l a t e 880 Moss St r ee t , between Folsom and Howard S t r ee t s (p la te 880); there were f i s su r i ng and slumping i n the block pavement, as along Columbia

p l a t e 89A S t r ee t between Folsom and Harrison S t r ee t s (p la te 89A). and sharp f l ex l r e s of the paved s t r e e t s and car t racks , as on Sixth S t r ee t j u s t south o f Howard.Street[loc. 2091. These e f f ec t s point simply and c l ea r l y t o the great magnitude of the i n t ens i t y thruout the grea ter pa r t of t h i s o ld swampy d i s t r i c t .


TABLE 7.Spec i f i descriptions of ground failures in Son Francisco City and County-Continued

Loea- Fig- Fail- Accu- Year of Reference Quotation t ion "re ure ra- earth- NO. NO. type cy quake

p l a t e 898

p l a t e 89C

Attention has already been d i rec ted t o the slumping o r flow movement t o the ea s t alone t h e lone ax is o f t he area. The heavily b a l k e d car-tracks an Bryant S t r ee t , a t the crossing

with Fourth S t r ee t , were sharply f lexed l a t e r a l l y , tho bounded by black paving. (P la te 898.) This was a t the eas te rn end of t he d i s t r i c t where t he marsh formerly bent t o the south around t h e f lanks of Rincon H i l l , a mass o f firm sandstone r i s i n g from the f loor of Mission Valley. No s imi la r sharp f lexures were encountered along east-west s t r e e t s i n the western or cent ra l port ion of the d i s t r i c t , tho l a t e r a l displacement and f l a t , sinuous curvings of the s t r e e t l i ne s were common enough; notably on Harrison S t r ee t between F i f t h and Sixth S t r ee t s , and on Folsom S t r ee t between Fourth and Seventh S t ree ts . Both these s t r e e t s cut across t h e d i rec t ion of the flow movement a t a small angle. These phenomena are easy t o understand i f , as seems ce r t a i n , Rincon H i l l served as a so l i d but t ress against which the flow t o the ea s t was ar res ted , causing sharp crumpling of the surface near the bu t t r e s s , with l e s s disturbance f a r t he r away. This was combined with a s l i g h t tendency t o flow southward i n the southeastern p a r t o f the d i s t r i c t . . - __ The shaking caused the materials used i n f i l l i n g t o s e i t l e together,

and occupy l e s s space, so t h a t t he surface over the whole d i s t r i c t ,, was lowered by amounts varying from a few inches t o 3 f e e t or more. This is c l ea r l y seen i n the change of s t r e e t leve ls along the margin of the so l i d ground, where the car r a i l s a ie -bent downward i n l i t t l e mnoclines. Occasionally a s t r uc tu r e with a r i l a f i ve ly mod founda- t i on remains a t its former leve l , with the whole neighboFhood deprest about it. Such a case i s exemplified on Sixth S t r ee t , a l i t t l e south of Howard S t r ee t [loc. 2091, near the margin o f the area. (Plate 89C.) The flow movement i s thoueht t o be due s i m ~ l v t o the ac t ion of e rav i tv . - . . . . the loose, water-soaked material being compacted i n t o l e s s volume by the shaking. Besides t h i s sinking of the d i s t r i c t , and its flow muement, mention has been made of the deformation of i t s surface i n to i r r egu l a r waves, t rending approximately eas t and west p a r a l l e l with the length of the d i s t r i c t . Along the s t r e e t s running approni- rnately north and south, a t r i g h t angles t o the elongation of the area, car r a i l s were bent abruptly t o the s i de , o r ra i sed i n arches, and sharp an t i c l i ne s were formed i n the block pavements. Large square concrete s labs , used fo r sidewalk paving, were t h ru s t one over the other; and i n one o r two cases a s l a b en t i r e l y covered an adjoining one. These phenomena indica te shortening by compression i n the north- south d i rec t ion . On the other hand, however, a s t re tch ing o f t h e surface i s sham by f i s su r e s i n the paving; by places wherewedge;- like-61ocks were deprest below the general level; and by,the r a i l s of car\ tracks which were pulled apar t i n amounts varying from 8 t o 12 inches. O~ving t o t he r e l a t i v e l y great and very var iab le s t r uc tu r a l $treength\of paved s t r e e t s and heavily ba l las ted car tracl is- ,~~these phenomena are not developed regular ly nor frequently enough t o afford a s>izfactory t e i t o f the hypothesis t ha t they are d i r ec t l y associated with the rave forms i n to which t he surface of t h i s d i s t r i c t was thrown. Besides owing perhaps t o t he varying r i g i d i t y o f t he materials which make up the surface o f the s t r e e t s and building p lo t s , the wave forms themselves, tho generally prevalent , are not pe r s i s t en t i n t h e i r extension. The compression and distension e f f ec t s , however, are believed t o be due t o the same cause as t ha t which generated t he wave farms; for there i s no evidence of any t r u e shortening, o r lengthening, of t he north-south dimension of t h i s d i s t r i c t , nor i s there any proba- b i l i t y of t h i s having occurred.

In addit ion, then, t o the flow movement and the s e t t l i n g together of the loose materials causing depression, there was some s o r t of rhyth- mic movement i n t h i s loose ear th which produced wave forms i n t he surface, with places o f compression and places o f s t re tch ing . It probably was t h i s movement which was most e f f ec t i ve i n producing St ruc tura l damage. I t i s not believed t h a t these surface waves were t rave l ing waves "frozen" as the shock subsided. I f they had been of t h a t character , the gmund surface should be more broken than it

TABLES 5-9 133

TABLE 7 .Spec i f i c descriptions of ground failures in San Francisco City and County-Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on "re uro a - earth- No. No. type cy quake

Quotation

appeared t o be; f a r i n r e l a t i ve ly r i g i d materials such waves must develop open f i s su r e s along the crests, which would close with crushing in the troughs. It must be noted, without any attempt a t explanation, t ha t the des t ruc t ive e f f ec t s of great magnitude which have been described above. are o r ac t i c a l l v confined t o the "made" land which occupies the old marsh s i t e . Southeast of Brannan S t r ee t , where formerly lay Mission Bay, such

e f f ec t s are of l e s s magnitude, i n general; are l e s s regular i n t h e i r occurrence and are, on the whole, l e s s prevalent .

B 1906 Smz Francisco The Fourth and Sixth s t r e e t sewers were a lso grea t ly damaged, some + ChronicZe, of them showing a ve r t i c a l and horizontal movement of as much as f i ve 1906~ . o r s i x f e e t , and port ions w i l l have t o be reconstructed.

A 1868 Lawson and others, A t the corner of Fourth and Bryant S t r ee t s , walls were cracked and + 1908, damaged; Fourth S t r ee t near Bryant opened i n places and a t the cross- I p. 437. i n s of Harrison and Fourth the r a i l r oad t rack s e t t l e d about 8 inches,

the planks between the r a i l s r i s i n g about 10 inches.

A 1906 Himmelwright, CALIFORNIA CASKET CO.'S BUILDING. Mission S t r e e t , between Fifth 1906, and Sixth S t ree ts . * * * p. 175 and 179. The leve ls on the water tab le i nd i ca t e t ha t the northwest corner

*: i s about 112" lo.ier than the nortlieast corner .

C 1906 Hall, I t would be tedious in these a r t i c l e s which t he wr i te r i s endeavor- 1906, ing t o keep within readable l i m i t s t o catalogue too many dry and p. 32. hard f ac t s made about hard and s o f t land, so he does not undertake t o

t r a ce in d e t a i l the ou t l i ne of the Mission bay and estuary, s a l t marsh and f resh swamp areas, as these have now again been made evident by the s t r e e t subsidence and o ther movements caused by our king shake. The region is a la rge one. To go slowly s t ep by s t ep around it as we did i n the case preceeding [foot of Market area, loc. 1931, on foot, as it were, would take too long; so we move rap id ly over most of it as in an auto, and, commencing an Townsend s t r e e t , near the Southern Pac i f ic Railroad yards, we not ice a disturbance near Cook s t r e e t , another i n Brannan, near Ritch; another near Harrison and Fourth; another near Folsom and Fi f th , and another near Howard and Six th . We f ind t ha t by these we may out l ine an the map the old s a l t marsh limit as f a r as t he grea ter impress o f t he earthquake's heel , which i s found i n the neighborhood of the new Postoffice.

MISSION AND SEVENTH STREET DISTURBANCE! It looks p r e t t y bad on Mission s t r e e t i t and near Seventh, t o see the + whole s t r e e t disturbed fo r abbut 700 f ee t i n length, t o see t h a t t h i s

disturbance extended f a r d a d Seventh , k t r ee t . and t ha t an area of the adjacent land had sunk. As an American one cannot t h a t the new Postoffice

building escaped, though barely, being i n t h i s area of depression. As a San Franciscan who knew t h i s spot f i f t y years ago, who saw i t a marsh with a l i t t l e stream runnine throueh i t . iol>o saw hunters . . wearing gum boots tramping about shooting jacksnipe i n t ha t very area, who l a t e r saw i t drained fo r market gardening, and s t i l l l a t e r saw it f i l l e d t o a depth of ten o r f i f t e en f e e t with sand dumped off a bank from s ide dump cars, and then saw it occupied by l i g h t wooden houses f o r a score and a ha l f o f years, it seems en t i r e l y na tura l t ha t a r e a l earnest earthquake should make it s e t t l e and move j u s t as it has s e t t l e d and moved. I t never had an inducement t o get down t o a good bearing before. Now i t has been shaken t o where it will probably s tay , and San Francisco w i l l be the b e t t e r f o r it.

In the block south and ves t of tlie Postoffice t h i s o ld John Sul l iv+ marsh formerly headed. I t s course was tomard t he east, joining an area of s a l t marsh which bordered Mision bay. * * The facts-now are tha t under the earthquake influence the f i l l i n g over t h i s marshy area 1185 s e t t l e d at a number of laces and to deoths of from a few inches ~~~ ~~ . ~~ ~~ . t o three or three and one-half f e e t . One of the most pronounced set t lements is the one re fer red t o on Mission and Seventh where the

134 HISTORIC GROUND FAILURES IN NORTHERN CALIFORNIA TRIGGERED BY EARTHQUAKES ~ TABLE 7 .Spee i f i c descriptions of ground failures in San Francisco City and County-Continued

i

Loca- Fig- Fail- Accu- Year of Reference t i on "re "re ra- earth- No. No. type cy quake

Quotation

I subsidence has reached a maximum of about three and one-half f e e t , as judged by t he f loor of the Postoffice building and t he movement toward t he bay, as judged by the s t r e e t railway t rack and alignment of t he t r o l l e y l i n e support poles, has extended for 300 tq 600 i n the length of Mission s t r e e t , reached a maximum o f about f i ve f e e t a t a point 175 f ee t south and west o f Seventh. ~ l a t > i ~ g , t h e l i nd t e of t h i s disturbance on t he map, they are seen t o coincide as near as can be measured with t he out l ine o f the o ld Sull ivan harsh as shown by the Coast Survey map o f 1857, and as the wr i t e r d i s t r nc t l y remembers it t o have been. 1

Duryeo and others, 1907, p. 265.

* * * a nwnber of brick warehouses on the north s i de of t he southern Pac i f ic Railroad, between Fourth and Sixth S t r ee t s , * * * t h e i r s e t t l e - ment during the earthquake, with respect t o the r a i l r oad r i g h t of way, jus t south of them, being about 2 fee t . I

I I

On Fi f th S t . , between Folsom and Harrison Sts . , the brick sewer s e t t l e d with the adjacent land, i t s crown was destroyed and t he channel had become f i l l e d with sand which blocked up the sewage t o a p n g e m u s extent . ~

I Lawson and others,

1908, p. 245.

Mint.-- * + The southwest corner i s the lowest, being 0.498 foot = 5.976 inches (mean) below the northwest corner. r * * I The deformation indicated by t he above measurements can not be wholly

r e f e r r ed t o the earthquake, s i nce it i s qu i t e probable t ha t the struc- t u r e s had s e t t l e d somewhat before t h a t event. I t appears, hohever, t o be des i rab le t o put t he measurements on record fo r fu ture refhrence.

I

[Picture caption] Settlement on S ix th S t r ee t . * * * j u s t south o f Howard St. The amunt of t he drop a t t he lamp pas t * * was f u l l y 2 f t . The sidewalk north of t h i s pa in t and t he s t r e e t a t t h e junction of Howard appears t o have s e t t l e d but very l i t t l e . I

Derleth, 1906b, p. 553.

Fig. 13 shows a drop i n Howard S t . Where t h e men are standi$g a sidewalk on foundations has remained i n place. [Picture caption, p. 5511 STREET SUNKEN; SIDEWALK IN PLACE BECAUSE ON FOUNDATIONS.

A sinall crevice opened, as i n 1865, on Howard S t r ee t beyond Sixth S t ree t .

1868. October 21; IX. * * As i n 1865, a small crevasse w b opened on Howard S t r ee t , beyond Sixth. I

Sunday Record- Heratd, 1906.

Twain Te l l s Humors of 1868 Earthquake. * * r A crack a hundked fee t long gaped open s i x inches wide i n the middle of one s t r e e t $Id then shut together again with such force as t o r idge up t he meetink ea r t h l i ke a slender grave. I

[Picture caption] S ix th S t r ee t , near Howard. Once occupied by marsh. S t r ee t dropt near ly 3 f e e t . Sidewalk held up by p i l i n g founda- t ion of a building. H. 0. W. ~

!

Lawson and others, 1908, p l a t e 89C.

Gilbert , Hlonphre , Sewell, and Soul< 1907, p. 97 and 98, p l a t e 62, p l a t e 63, p l a t e 64.

The steel-frame and grani te post-office building (Pls. XLII,B; XLIII; XLIV) was car r ied on i so l a t ed g r i l l age foundations, each column having i t 5 o m footing. The diagonals of the bui ld ing ran near ly nokth and south and e a s t and west, the south corner being a t Seventh and Mission s t r e e t s . To the south and west of Mission s t r e e t was an elonkated, narrow, curved area i n which the earthquake darnage was very severe [see lo= . 2051. I t was c o m n l y reported t h a t t h i s area, which was

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TABLE 7 . S p e e i f i e descriptions of ground failures in San Francisco City and County-Continued

Loca- Fig- Fa i l - Accu- Year of Reference t ion ure ure ra- earth- NO. No. type cy quake

Quotation

Gilbert , Hmphrey, Sewell, and Soul.5, 1907, P. 44, p l a t e 438.

Gilbert , Humphrey, Sewell, and Soul6, 1907, P. 99, p l a t e 438.

Lamon and others, 1908, p. 238.


Jordan, 1907, p. 154.

D u m a and others, 1907, p. 288, p l a t e 38.

no t f a r from the south corner of the post-office building, was a stream bed o r ravine t h a t had been f i l l e d within the recol lec t ion of the o lder inhabi tan ts of San Francisco. * * * Mr. Roberts, who i s evidently a cool and accurate observer, seemed o f the opinion t ha t the material under t he building was a na tura l deposit , and not an a r t i f i c i a l fill. But toward the south it was not o f a nature t o insp i re confidence i n i t s carrying power a t t he depth shown on the foundation plans. He accordingly obtained au thor i ty t o lower the footings wherever the material a t the depth shown on the plans seemed unre l iab le , so t ha t the footings o f the south ha l f o f the building were lowered--some of them, as I remember h i s statements, t o a depth of 20 f ee t o r more below the basement-floor level . A t any r a t e , he car r ied them t o a point where the material , i n h i s judgement, was su f f i c i en t l y hard and compact. A l l t h i s underlying inaterial is very sandy; but a t considerable depths, I understand, gravel appears, and the combination i s almost as hard as hardpan.

The ground a t the corner o f Seventh and Mission s t r e e t s s e t t l e d about 5 f e e t (PI. XLIII, 8) . The f l oo r of the [Post Office] building w a s s l i g h t l y cracked a t t h a t point , and Mr. Roberts s t a t e d t ha t there was a s e t t l i n g of about 1 3/4 inches.

The s t r e e t went down about 4 o r 5 f e e t a t this point [Mission St. i n f ront of the Post Office] as a r e s u l t o f the earthquake (PI. XLIII, 8).

The new United Sta tes Post-office building, (p la te 94B), a t the corner of Seventh and Mission S t r ee t s , was j u s t on tile margin of the d i s t r i c t [see lac. 2051. I t is a s t e e l and grani te s t r uc tu r e , r e s t i ng upon a foundation of p i l i n g driven t o a considerable depth * * * . A t i t s southirest corner, the s t r e e t s are deformed i n t o grea t waves, some with an amplitude of a t l e a s t 3 f e e t , causing f i ssures and sharp compres- s iona l arches i n t he pavement and sidewalks. Some of the grani te f lanking s t r uc tu r e s , which d id not r e s t upon the p i l e foundation of the building, shared t h i s undulatory movement.

New Post-office.-- * * The southwest corner is the lowest and is the only one t h a t s e t t l e d material ly, being about 0.393 foot = 4.72 inches lower. The outer walls have cracks i n inany places. This i s a f a i r l y good showing for a bad foundation. [Because no immediately pre-earthquake measurements are ava i lab le , it i s not c e r t a i n t h a t a l l settlement occurred during the earthquake.]

[Picture caption] San Francisco Post-office, Mission and Seventh s t r e e t s . ear corner of building is on edge of o ld marsh. Ground over marsh sank and lurched.

[Picture caption] At the comer of Mission and Seventh Sts. The ground is a loose f i l l and s e t t l e d considerably, while Mission St. has apparent- l y been thrown t o the southeast a t t h i s point a t l e a s t 2 ft.

[Picture captian] Fig. 27--General Postoffice, Southwest Corner, Show- ing Severe Distort ion and Subsidence of the Sidewalk and S t r ee t Levels.

r * on t he " f i l led" i n land near t he new Post Office, the building, p i l ed upon a c lay foundation, suffered but l i t t l e , while the s t r e e t i n f ront , made upon twenty-three f e e t of sand over a marsh, sank two fee t and s l i d out from the building about one and one-half fee t .

The Post Office Building * * * was an p i l e s * * * and the earthquake wave motion moved through t h i s f o r e s t foundation, following and develop- i n g l i ne s o f l e a s t res i s tance , with consequent promiscuous racking a l l over the building. A t t h e four coiners the cracks were most pronounced * * * .



Loca- Fig- Fail- Accu- Year of Reference Quotation t i on ure "re ra- earth- No. NO. type ey quake

A 1906 Himelwright , UNITED STATES POST OFFICE. N. W. Cor. Seventh and Mission S t r ee t s . x 1906, * * * At the southwest corner, the-ground s e t t l e d about 2 ft . a t t he p. 192. , building l i n e and about 5 ft.,at"the%urb, the e n t i r e surface from the + building l i n e moving out about 5 f t . do the south. This d i s t o r t ed t he

sidewalk and s teps of t he t w entrancQs, there being cracks i n the < j o in t s of the cement sidewalk s l a b g 8 " wide. It was necessary t o place two temporary wooden s teps of about 8" r i s e from the sidewalk i n i t s s e t t l e d pos i t ion t o t ha t port ion of the s teps which remain approximately a t t he or ig ina l height .

A 1906 Himelwright, [Picture caption] UNITED STATES POST OFFICE. Northeast Comer of 1906, Seventh and Mission St ree ts . A t the curb i n f ront of the building, p. 193. on the right-hand s i de , the ground s e t t l e d 5 f e e t and roved t o t he

ea s t away from the building about 6 feet . A t t h e building l ine , the ground s e t t l e d about 2 f e e t , causing the displacement of t he grani te coping, s teps , etc. , a t the sidewalk leve l , as shown. The sidewalk was o r ig ina l l y a s t r a i gh t grade on t he right-hand s i de where the sag is now sholm. The northwest corner of the building was badly racked by the earthquake, and temporary shores were i n pos i t ion when the photograph was taken. This bui ld ing was only s l i g h t l y darnaged by the f i r e .

A 1906 Hyde, United Sta tes Post Office.-- * * The e f f ec t o f the earthquake 1906a, throughout t h i s v i c i n i t y has been most marked. S t r ee t s i n t h i s neigh-

x p. 701. borhood have s e t t l e d very considerably and the sidewalk has a l so ser ious ly sunk. Mission St . , a t t he corner o f 7th, has been thrown * bodily southward t o the extent of a t l e a s t two fee t . I t i s evident t ha t the building i t s e l f s e t t l e d s l i g h t l y , inasmuch as serious cracks were developed on the grani te facing a t t he southwest, northwest, and the northeast corners, and these cracks presumably extend i n t o the brickwork.

A 1906 Derleth, The magnificent Post Office building, corner of Mission and Seventh 1906a, S t s . , r e s t s upon sand, and under one end of it a t one time ran an p. 503. old creek bed. This building r e s t s upon p i l e s and heavy concrete

walls , but has been badly cracked due t o the severe convulsion of the ground. I t has been unharmed by the f i r e , but w i l l need enten- s i ve repa i rs .

B 1906 Gilbert , Hmph~ey, * * r there was a p a r t i a l l y erected s t e e l frame (PI. XLII, B) on Sewell, and SoulC, t he southwest s i de of Seventh s t r e e t , near t he post-office. Before 1907, t he earthquake a l l t h e columns were plumb a n d i n t r u e alignment. As P. 99, a r e s u l t of t he shack there was a l a t e r a l s h i f t i a o f t he column p l a t e 628. bases--the r e l a t i v e movement being a l m s t , 2 f e e t injsome places--at

the ce l la r - f loor level . The basement walls o f t he incomplete building were a lso sh i f t ed horizontal ly; a t t he edst-corner, where t he walls had met a t a r i g h t angle, they had been ruptured by a ve r t i c a l crack and moved l a t e r a l l y i n such a way t ha t t he angle between then was reduced t o about 75' x r * .

212 C 1906 Los AngeZes HeraZd, [Picture caption] This remarkable photograph shows haw Mission x 1906. s t r e e t , San Francisco, sunk away from the curb t o a depth of f ive fee t . The pos tof f ice i s located one block north, where the ground was upheaved t o a height of several f e e t . In t h i s area o f "made" ground houses were completely overturned and i n severa l instances sank f a r considerable distance below the l eve l of t h e s t r e e t .

A 1865 Lairson and a thers , On the marshy lands i n the v i c in i t y of Howard and Seventh S t r ee t s * X

1908, the ground was heaved i n some places and sank i n a thers . Lamp-posts p. 449. were throirn out of perpendicular, gas-pipes were broken, e t c .

B 1865 Holden, 1865. October 8; I X ; * * On the marshy lands i n t he v i c in i t y of + 1898, Howard and Seventh s t r e e t s , lamp posts , water pipes and gas pipes p. 66. were broken and t h r o m out of pos i t ion . The ground on Howard S t r ee t ,

• from Seventh nnoth t o Ninth, cracked open, leaving a f i s su r e near ly an inch wide.

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TABLE 7 . S p e c i f i c descriptions of ground failures in Sun Francisco City and County-Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t i on "re ure ra- earth- NO. NO. type cy quake

213 C 1906 Lawson and others, The blocks between t he o ld tide-marsh area, extending ea s t from near 1908, the Post-office [loc. 2051, and the former course of hlission Creek p. 229. i loc . 2141, give evidence i n the form o f cracked foundation walls ,

broken concrete c e l l a r f loors , e t c . , of i n t ens i t y values high i n Grade C.

A 1906 Lawson and others, [Mission Creek zone] A s s t a t e d b r i e f l y above, a s imi la r d i s t r i c t 1908, i loc . 2051 of high i n t ens i t y occurs i n an area of made land along the p. 238 and 239. lower Port ion of the former course o f Mission Creek. This d i s t r i c t

va r i e s - i n width from 1 t o 2 blocks, extending from near the corner of Ninth and Brannan S t r ee t s westward fo r about 5 blocks, then southwestward for about 2 blocks mare; and f i na l l y , westward some 4 blocks more t o a point on Nineteenth S t r ee t j u s t e a s t of Dolores S t ree t . Mission Creek was formerly a sinuous t i d a l stream, with narrow

fringes of s a l t marsh about i t s banks. Near i t s mouth the stream wound around a rocky point where the serpentine h i l l s of the Patrero rose abruptly from i t s southern bank. Here along its margin, i s found the most sudden t r an s i t i on from hizh t o low in t ens i t v t ha t is

p l a t e 890 p l a t e 90A p l a t e 90B

p l a t e 91A

p l a t e 91B

" anywhere encountered i n the c i t y . Along Dore St r ee t , a narmw a l l ey running from Bryant S t r ee t t o Brannan S t r ee t , between Ninth and Tenth S t r ee t s , the s t r e e t pavement was broken i n t o a s e r i e s of waves. The photographs, p l a t e 890, looking along Dore St r ee t from Bryant toward Brannan S t r ee t ; p l a t e 90A, looking from Brannan S t r ee t i n the reverse d i rec t ion; and p l a t e 90B, showing i n d e t a i l the trough o f one of these waves, 'with the f i s su r i ng of the pavement near the f a r t he r c r e s t , ind ica te more c l ea r l y than words tlie great i n t ens i t y manifested here. Less than 2 blocks south on the h i l l s lopes, more than 50 percent of the chimneys were l e f t s tanding, and no ser ious s t r uc tu r a l damage was noted. No comment seems needed t o es tab l i sh c lear ly the f ac t t ha t t he change i n the character of the ground, t h i s being the only var iab le fac tor , is i n some way the cause of the change i n the degree of in tens i ty . On Ninth S t r ee t , e a s t o f Dore St r ee t , between Bryant and Brannan

S t r ee t s , the block pavement was badly damaged by f i ssur ing , slumping, and the formation of surface waves. Frme dwellings were thrown from t h e i r underpinning, and a few collapsed. P la te 91A shows a wave trough near Bryant S t ree t , with the r e su l t i ng disturbance of the pavement. The dwellings immediately i n the trough have dmp t from t h e i r foundation posts . I n P la te 918, looking along Ninth S t r ee t from near Brannan St ree t , i s shown the depression and f i s su r i ng of t he s t r e e t and i t s slumping o r flow westward toward t he former channel of a short branch of Mission Creek, which occupied the present location of Dore St r ee t . S t r ee t s . curbine. car t racks . e t c . . are deflected -. from 6 t o 8 fee t from t h i i r former p o s i t i o n s . The frame dwellings were not destroyed, but a careful examination of the p ic ture w i l l show tha t most of them are badly injured. Many were l e f t i n a dangerous condition by the shock. On Tenth S t ree t , between Bryant and Brannan S t r ee t s , l e s s violence

U was noted and the slumping of flow eastward (toward the channel of the l i t t l e branch of Mission Creek) i s scarcely noticeable.

C 1906 Gilbert , Humphrey, As i n d i s t r i c t s outside of San Francisco, the grea tes t damage w s s Sewell, and Soul6, done t o those s t ruc tures having i n su f f i c i en t foundations b u i l t an

x 1907, so f t alluvium o r f i l l e d ground. The s e t t l i n g of the ground i n the p. 26. mud f l a t s along San Francisco Bay and o f t he f i l l e d ground i n old

water courses was accompanied with great destruction. It was i n such ground t h a t the grea tes t number of breaks occurred i n the cast- iron gas and water mains and t he sewers. The breaks i n the seriers were not so evident as those i n the gas and water mains, f o r the reason t ha t the l a t t e r were under pressure and breaks i n them resu l ted in. breaks i n the s t r e e t s themselves. The most noticeable destruction r e su l t i ng from the s e t t l i n g of so f t o r f i l l e d ground occurred i n Howard [now South Van ~ e s s ] and Shotwell s t r e e t s between Seventeenth and Eighteenth s t r e e t s [loc. 2151, Bryant s t r e e t between Ninth and

138 HISTORIC GROUND FAILURES W NORTHERN CALIFORNIA TRIGGERED BY EARTHQUAKES

TABLE 1 .Spec i f i c descriptions of ground failures in Son Francisco City and County-Continued

Loca- Fig- Fail- Accu- Year of Reference t ion ure ure ra- earth- NO. No. type cy quake

Quotation

and Tenth s t r e e t s , Oore s t r e e t between Bryant and Brannan s t r e e t s p l a t e 6A (PI. VI, A). and a t the corner of Seventh and Mission s t r e e t s

[ loc. 2101. The s e t t l i n g was grea tes t i n Howard, Dore, and Bryant

x s t r e e t s , being i n Dare s t r e e t a t l e a s t 5 f e e t .

1906 Gilbert , Humphrey, Sewell, and Soul6, 1907, P. 8, p l a t e 5, p l a t e 68.

1906 San Jose Mercury, 1906~ .

1906 Gilbert , H q h r e Sewell, and Soul< 1907, P. 9, p l a t e 6A.

1906 Gilbert , Humphrey, Sewell, and Soulk, 1907, p l a t e 56.

1906 Hyde, 1906b, p. 739.

1906 Hyde, 1906b, p. 740.

The f i l l e d d i s t r i c t s o f San Francisco afford severa l examples, and two of these are i l l u s t r a t e d by Pls. V and V I , B. The view shown i n PI. V i s northwestward on Ninth s t r e e t , near Brannan. Before the earthquake the car t racks and curb l i ne were s t r a i g h t and approximately leve l , and t h i s condit ion was not disturbed on the r e l a t i ve ly firm ground shown i n the distance. In the nearer p a r t of the view the s t r e e t crosses a t r a c t of made ground created by f i l l i n g a va l ley t r i bu t a ry t o a narrow t i d a l i n l e t ca l led Mission Creek. The descent of t h i s valley was southwestward, and the made ground flawed i n t ha t d i rec t ion , carrying s t r c e t and buildings with it. In taking the photograph reproduced i n PI. VI, B, t h e camera stood on ground made by t he f i l l i n g of Mission Lagoon, an expansion of Mission Creek, and was pointed northward, commanding a port ion of Howard s t r e e t Lloc. 2151. The made ground here flowed northeastward and t he buckling of s t r e e t - ca r t racks was caused by i t s motion. Where the same ear th flow crossed Valencia s t r e e t [ loc. 2161 t he horizontal mvement amounted t o 6 f e e t .

[Picture caption] Twelfth [17th 11 and Mission S t r ee t s . The sidewalk was t o rn open here. [See a l so loc. 217.1

Another example of the e f f e c t on t he f i l l ed - i n land i n t h i s p a r t of the c i t y i s shoirn i n PI. V I , A, a view of Dore s t r e e t between Bryant and Brannan s t r e e t s . The s e t t l i n g o f t he s o f t ground caused the s t r e e t t o drop a t l e a s t 5 f e e t a t t h i s place.

MAP OF SAN FRANCISCO SHOWING BURNED DISTRICT; [This map a lso shows "Principal earthquake breaks i n s t ree ts . " The locutions of these breaks have been p lo t t ed on P la te 3.1

The most important loca l set t lements and transverse movements occurred in the v i c in i t y of the Valencia Hotel between 18th and 19th S ts . , on Valencia St. [loc. 2161, on Howard St . between 17th and 18th [lo=. 2151; on 14th. between Mission and Howard [loc. 2141; on Folsom, a t the corner of 17th [loc. 2151; on Mission, a t the corner of 7th [ loc. 2101, and on Van Ness Ave., between Vallejo and Green Sts. [loc. 2211.

On Howard S t . , a t the corner of 17th S t . , very complete destruction o f the brick sewer, as well as most o ther pipes and conduits i n the ground, was caused by t he extensive set t lements i n t h i s region. On Valencia St., near 18th St . [ loc. 2161, s im i l a r ruptures were produced.

44 A 1906 Lawson and o thers , Again, along t he creek bed from Folsom S t r ee t , between Seventeenth 45 1908, and Eighteenth S t r ee t s , t o the v i c i n i t y of Valencia S t r ee t a t Eighteenth,

D. 239. e rea t destruction was consoicuouslv orevalent . * * * The south s i de of 43 p l a t e ~ Z B ,

OI p l a t e 93A, p l a t e 90C.

tioward S t r ee t , between ~ e v k n t e e n t h &d Eighteenth S t r ee t s t + * . As i n o ther places, the s t r e e t s were deprest , f i s sured , and thrown i n t o waves. Car r a i l s were arched and bent l a t e r a l l y i n a v io len t fashion.

46 A 1906 Lawson and others, [Picture caption] Eighteenth S t r ee t , j u s t e a s t of Shotwell. Fissuring 47 0 1908, and depression of pavement. H. 0. W.

p l a t e 90C.

A 1906 Derleth, 1906b,

0 p. 554.

Fig. 20 shows a s t r e e t view, taken April 25, a t the corner of Howard and Seventeenth S ts . , where the ground was much d is tor ted . The car t racks are twis ted out o f shape, the brick sewer i s broken and t he water and gas pipes are wrenched and snapped.

TABLES 5 9 139

TABLE 7 . S p e c i f i c descriptions of ground failures in San Francisco City and County-Continued


B 1906 Himmelwright, [Picture caption] RESIDENCES. Howard S t r ee t near Seventeenth 1906, S t ree t . The upper view shows two buildings that ,have been t i l t e d p. 18. badly out of plumb by the ?a<Kquake. The rear port ions of - the x buildings s e t t l e d about 10 fee t . The telegraph poles are approxi-

mately plumb. Note the b'uilding qh the r ight , the corner of which has broken i n t o the side'of the t i l t e d one. The low:- view shows Howard S t r ee t , looking west. The f ront of the

two buildings shown i n the upper view are approximately i n t he centre. 8 One building near the left-hand s i de has t i l t e d away from the s t r e e t

l ine u n t i l it almost disappears.

216 4&l 8 A 1906 Hyde, 488 x 1906b,

p. 739.

The m s t important and i n t e r e s t i ng case of set t lement and~throir ing out of alignment of s t r e e t s i n San Francisco, due 70 t h e v ib r j t i ons of the temblor, was tliat o f Valencia S t . , between U8th and 19th Sts., in the Old Mission d i s t r i c t . At t h i s point there >as f o r m e r l ~ a t i d a l stream, know as Mission Creek, whose existence had long since ceased owing t o the fact-that its course had been f i l l e d i n and t he land s o reclaimed h5d betom>\,thickly b u i l t up. The earthquake caused a settlement of f o m 6 t o 8 ft. f o r a distance of from 150 t o 200 f t . along t h i s s t r e e t , and a t the same time sh i f t ed t he e n t i r e s t r e e t , with adjacent lan&eai t r r rd through a naximm distancalof 9 t o 10 f t . This change i n alignment and grade could, of course, mean nothing l e s s than the e n t i r e destruction of a l l water and gas mains, e l e c t r i c l i gh t i ng and telephone conduits, sewers, cable conduits, r a i l r oad t racks , e t c . The breakage of these important l i ne s , espec ia l ly t o t he water mains, w w o f grea tes t s ignificance. I n t h i s case the destruc- t ion of the water pipes, o f which a 28-in. and a 16-in. were found i n t h i s s t r e e t a t t h i s point , meant the cu t t ing off of a large pa r t of the water supply of the port ion of t he c i t y which was &on t o be i n flames.

A 1906 Lawsan and others, A t Eighteenth and Valencia S t r ee t s there was a serious break i n the X 1908, water;pipe. Here, on both s ides of the s t r e e t , tile ground sank about

P. 239, 6 feet;'causine the roadway t o arch i n a verv noticeable way. Ten- p l a t e 938.

- inch car r a i l s were bowed up i n t o arches from 24 t o 30 inches i n height. The Valencia S t r ee t Hotel collapsed s o t h a t occupants of the fourth s t o ry could s tep out i n t o the s t r e e t . Casualt ies i n t h i s d i s t r i c t can never be known accurately, owing t o t he immediate onset of the f i r e , and the complete devastation i t produced.

C 1906 Duryea and others, I n f i l l ed - i n t i d a l areas, marsh-lands and swamps there was considerable movement i n a nmber of places [the grea tes t near 16th Sr. [ la th S t .? ] and Valencia S t . , where the set t lement was 5 f t . and the l a t e r a l movement 6 f t . ) and i n a l l such disturbed areas t he sewers - were destroyed.

A 1906 Schussler, APPENDIX D. The following are ex t r ac t s from the repor t of City 1906, Engineer Woodward on t he breaks i n the San Francisco sewer system p. 43. caused by the earthquake as published i n the "San Francisco Chronicle"

of June 17, 1906: * * r '!On Valencia s t r e e t , between Eighteenth and e Nineteenth s t r e e t s , there was a l a t e r a l mvement t o t he ea s t , with a X maximum of s i x f e e t and a subsidence with a maxirmm of f i ve fee t .

This occurred i n made ground over the o ld Willows marsh, one of the t r i bu t a r i e s of Mission creek."

8 1906 Derleth, 1906b, p. 551.

X B 1906 Derleth, 1906c, p. 581.

8

The Valencia Hotel, it w i l l be remembered, was s i t ua t ed on Valencia St., near 18th. on f i l l e d ground, where once ran the o ld Mission o r I s l a i s Creek. The Valencia Hotel and o ther cheap brick and frame buildings i n t ha t region from Valencia t o Howard Sts . very generally collapsed. Many l i ve s were l o s t i n the Valencia Hotel.

[Figure caption] STREET SUBSIDENCE IN SIW FRANCISCO. VIEW ON VALENCIA ST., NEAR 18TH ST., OPPOSITE SITE OF VALENCIA HOTEL. ( I t was a t t h i s place t ha t s t r e e t water mains were broken. The st,reet dropped about 4 f t . and moved eastward about 6 f t . a t the maximwn point.


TABLE 7.Speeifie descriptions of ground failures in San Francisco City and County-Continued

Loca- Fig- Fail- Accu- Year of Reference t ion ure ure a - earth- No. No. type cy quake

Quotation

B 1906 Son Francisco I .Chronicle,

1906a.

B 1906 l o s Angetes DniZy Times, 1906b.

I B 11106 Los Angetes DniZy Times, 1906b.

A 1906 The Evening Wisconsin, 1906.

A 1906 Schussler, 1906, p. 30.

X A 1906 Rickard, 1906b, p. 287.

[picture caption] Ruins of the Valencia S t r ee t Hotel, showing the depression i n the s t r e e t . This i s t he bes t photograph o f the effect of the earthquake i t s e l f ye t published.

[Picture caption] Valencia Hotel, San Francisco, i n which fo r t y people were k i l l ed .

[Picture caption] San Francisco F l a t s Sunk One Story In to the Ground by Earthquake. Great Fissures i n S t r ee t . photo by H. C. Carr. On t he corner next the Valencia was a new s e t of three s t o ry f l a t s ,

j u s t completed, and mast of the f l a t s not yet occupied. As though someone had s t ruck it on top with a giant hammer, the e n t i r e building had sunk one s tory i n t o the-ground; you could walk r i gh t i n a t the second story.

BIG CREVASSE IN STREET. A t Eighteenth and Valencia there i s a crevasse i n the s t r e e t s i x f e e t wide and en t i r e sidewalks are torn up. The s t r e e t car t racks are badly twisted a l l through the southern sec t ion o f the c i t y and t r a f f i c i s a t a s t a n d s t i l l .

* * r the College H i l l Reservoir r * had beem emptied o f its con- t en t s 11,400,000 gallons, which it contained a t 7 A. M. April 18, by i t s main a r t e r i a l pipe, 22-inch diameter, and i t s companion pipe, 16-inch diameter, both an Valencia s t r e e t , having both been torn o f f and destroyed between Eighteenth and Nineteenth s t r e e t s by the sinking of Valcncia s t r e e t o f from one t o f i ve fee t .

VALENCIA STREET SUBSIDENCE. A number o f l e s s e r footmarks of our earthquake are t o be seen i n the s t r e e t between Seventeenth and Eighteenth and e a s t and south of Mission. These a l l coincide with the i r r e eu l a r l i m i t s o f our ind ica ted soec ia l lv s o f t soots i n rhe former ~. s a l t marsh area, and we follow them around u n t i l we come t o another pronounced case of subsidence and s l i p , which i s noticeable i n Valencia s t r e e t between Eighteenth and Nineteenth, i n Mission between Seventeenth and Eighteenth and i n Howard from Seventeenth and Eighteenth. Valencia s t r e e t shows subsidence of one t o f i ve and a ha l f fee t and s l i p of one t o s i n fee t for 450 f ee t i n length; Mission shows very s l i g h t subsidence and s l i p of only about one foot f o r about 400 f e e t i n length, while Howard shows a subsidence o f two t o three f ee t f o r over 500 f e e t i n length and a maximum s l i p o f about four f e e t . The l im i t s of the movement, p l a t t e d on t he map, exactly ou t l i ne the ravine i n which was formerly headed, between Mission and Valencia, "The Willoios," a San Francisco place of resor t . The whole area was i n those days m i s t land, with a l i t t l e stream i n i t fo r a p a r t o f each year, and which has been f i l l e d upon between hard h i l l s i d e s . Being s o f t beneath and on a down- grade i n the l i ne o f grea tes t earthquake v ibra t ion , the temblor found i n it an easy mark fo r a pronounced dermnstration. Again, a t i t s head between Valencia and Guerrero a s ide ravine came

down from the south. The s l i p across Nineteenth s t r e e t of about s i n and a ha l f f e e t , as shown by bowing of the l i n e o f curbing, ou t l ines the branch of the o ld depression, which was f i l l e d on a steep gradient and qu i t e na tura l ly s l i d eas i ly . [See l o t . 217.1

Valencia S t r ee t has sunk 8 t o 10 f e e t * + * . Down 18th s t r e e t a l so , from Valencia t o Howard [now South Van Ness], the ground has sunk on the north s i de along the center of the cabble-paved roadway and there i s a crack 12 t o 15 inches wide along t he l i n e of rupture. Neighboring houses show the e f f ec t s of disturbance. Evidence of a s imi la r kind is obtainable elsewhere i n t h i s v i c in i t y and it is noteworthy t ha t the be l t of deranged buildings and d is loca ted roadways follows exactly the l ine of the f i l l i n g over t he o ld creek.

A 1906 Schussler, One a f the most serious breaks i n t he main pipe l i ne s was caused by x 1906, t he earthquake shaking and s e t t l i n g down, by from one t o f ive fee t , p. 35. the region between Eighteenth and Nineteenth s t r e e t s , on Valencia

s t r e e t . Here an o ld swamp had been loosely f i l l e d i n , many years ago, by any and a l l kinds of material and,rubbish obtainable, the f i l l being twenty f ee t o r more i n depth.

TABLES &9 141

TABLE 1 .Spec i f i c descriptions of ground failures in San Frahciseo City and County-Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t i on ure "re ra- earth- No. No. type cy quake

217 A 1906 Lawson and others, On land made by f i l l i n g i n , "The Willows," a marshy t r a c t formerly 1908, extending up the Eighteenth S t r ee t Valley from Mission Lagoon, near p. 239, the corner of Nineteenth and Guerrem S t r ee t s , there was observed a

50 * p l a t e 94A. wnsiderable slumping or flaw movement of the surface. The photograph (p la te 94A) shows the Youth's Directory, a char i tab le i n s t i - t u t i on fo r boys, where the s t r e e t and building were moved northward and s l i g h t l y eastward, toward t he former channel and downstream, fu l l y 6 f e e t .

B 1906 Lawson and others, Near t he corner of Waller and Portala S t r ee t s , no t f a r north o f the 1908, head of Market S t ree t , i s a l oca l i t y , l e s s than a black i n extent , p. 240, where houses were sh i f t ed s l i g h t l y on t h e i r foundations; t h e i r upper p l a t e 900. s t o r i e s were moved f a r t h e r eastward (downhill) than the foundations

r * * . Here a t h in layer of sand reposes upon the slopes of a l i t t l e upland va l ley between the low serpentine h i l l s t o the ea s t and t he high cher t h i l l s t o the west. The ef fec ts are such as would be produced by a shaking downhill o f t h i s th in sand layer, with t he s t r uc tu r e s which r e s t upon it.

219 B 1906 Jordan, x 1907,

p. 123.

STREET AND SURFACE DEFORMATIONS Great d i s t o r t i on of the surface was bes t observed i n the s t r e e t s , and was found on the f i l l e d areas and i n some places, on the sand dunes. The bes t l o c a l i t i e s for observation were: * * * (5), Van Ness Avenue a t Eddy S t r ee t ; [Complete quotat ion under note 3 t ab l e 3.1

220 A 1906 The A~gonnut, [Picture caption] Point a t corner- o f Van Ness and Pac i f ic Avenues, 1906. San Francisco where t he f i r e broke out again, leading t o the destruc-

t i on of North Beach. [Picture shows a crack i n t he sidewalk w i t h , x some subsidence. ]

221 52 A 1906 Lawson and others, A t the corner o f Vallejo S t r ee t and Van Ness Avenue, f i s su r e s were 1908, formed i n the asphalt paving, sidewalk pavements were t h ru s t over p. 231. the curbing, and water-mains and sewers were broken. Buildings were

thmwn out of the ve r t i c a l , and foundations and lower s tory walls + were sh i f t ed and crusht . The wal l s about t he foundation of one brick building were ac tua l ly deformed i n t o undulations with much consequent cracking. This building was $0 badly damaged t ha t it had t o be taken down. Surrounding t h i s corner i s a small ovoid d i s t r i c t , about 2 blocks i n extent , i n which the i n t ens i t y rias c l ea r l y of grade B. This was once a sharp ravine and had been f i l l e d t o a depth o f 40 fee t i n order t o provide a su i t ab l e grade fo r s t r e e t s and buildings. The f i l l i n g was shaken together and moved s l i g h t l y downhill.

B 1906 Gilbert , Humphrey, A t one point on Van Ness avenue (see B, PI. LVI), where I happened Sewell, and Soul6, t o see the mains uncovered, a heavy water pipe, apparently about 1907, 20 inches i n diameter, had been broken i n t o pieces not more than 2 p. 118, feet.long. The t o t a l length o f the break, however, was not more p l a t e 56. than 40 o r 50 f ee t , s o f a r as I could judge from what I saw uncovered.

B 1906 Schussler, APPENDIX D. The following are ext rac ts from the repor t of City 1906, Engineer Woodward on the breaks i n the San Francisco sewer system p. 43. caused by the earthquake as published i n the "San Francisco Chronicle"

of June 17. 1906 ro. 341: "The v i c i n i t y of Van Ness avenue and Vallejo 5 t h is-bne o? t h e prominent pa in t s of i n t e r e s t . I t was found t ha t Van Ness avenue had been more o r l e s s a f fec ted from a point 150 f ee t south of Vallejo s t r e e t t o Union s t r e e t , the g r ea t e i t subsidence being two f e e t a t the crossing of Vallejo s t r e e t . There was a lso subsidence of Vallejo s t r e e t f o r 150 f ee t on each s ide of Van Ness avenue. There was a l a t e r a l movement t o the north on Van Ness avenue of about three f ee t on Vallejo S t r ee t , decreasing t o



Loca- Fig- Fa i l - Accu- Year of Reference Quotation t i on ure ure ra- earth- No. No. type cy quake

about one foot a t Green s t r e e t , t h e ground and buildings upon it having been moved bodily so t ha t now the buildings encroach upon the neighboring l o t s o r upon the s t r e e t . As a r e s u l t of the subsidence and l a t e r a l movement the seirers extending ea s t , south and west of the crossing of Van Ness avenue and Valleja s t r e e t were broken for about 150 fee t . The scene of the disturbance was an o ld f i l l of about f o r t y f e e t which had been made years ago i n the ravine leading t o the northwest t o the lagoon formerly ca l led Washerwoman's bay." [ ~ l l of the information re levant t o ground f a i l u r e occurrences i n the Chronicle repor t i s contained i n t h i s ex t r ac t by schuss1er. l

8 1906 Oakknd Tribune, * * * VAN NESS AVENUE. In no port ion of San Francisco i s t he vaga- 1 9 0 6 ~ . r i e s o f the temblor reg is te red as on Van Ness avenue. Do,? towards

the bay the houses facing on t h i s beaut i fu l boulevard have been twisted l i k e c&kscrews, and t he pavement is f i l l e d with gaps several f e e t wide and many f ee t deep.

8 1906 Lesl ie ' s WeekZ.q, [Picture caption] A mark of t he earthquake i n Van Ness Avenue. 1906e.

222 A 1906 Lawson and others, A port ion of Vnion S t r e e t , between Pierce and Ste iner S t r e e t s , not 1908, more than a quar te r of a block i n length, where a f i l l i n g had been

@ p. 232, made t o equalize the s t r e e t grade, was shaken down i n t o the adjacent 53 p l a t e 888. bui ld ing l o t on the north. The nor th sidewalk was sh i f t ed about 10

fee t t o the north, and deprest about 10 f ee t below its o r ig ina l leve l . The south sidewalk was deprest a few inches and sh i f t ed t o t he north from 2 t o 3 fee t . The paving and the cable conduit suffered more severe damage than a t any other point i n the c i ty . * r * The phenomena have no general s ignificance, however, despi te t h e i r s t r i k i n g character , being merely a s l i d ing o f unconsolidated material no t supported'on the sides.

C 1906 Oaklmd Tribune, Near Union S t r ee t the bitumen has been converted i n t o a s e r i e s of 1906~ . waves. Closer t o the mi l i ta ry reservation the e f f e c t of t he shake

upon the ear th i s even more apparent. Several grades were d i s t i n c t l y changed.

A 1906 Gilbert , Humphrey, The group o f buildings comprising the p lan t of t he San Francisco Sewell, and Soule, Gas and E l ec t r i c Light Company, b u i l t on the s o f t ground along San 1907, Francisco Bay j u s t west of Fort Mason, w a s badly shaken, and none

x p. 27. of the buildings escaped damage. * * r The ground s e t t l e d very considerably under the v ibra t ions o f the earthquake, and fu r t he r destruction was cuased by the unequal s e t t l i n g of t he building.

224 8 1868 Lawson and others, On the beach a t t he foot of Webster S t r ee t , below high-water mark, 1908, a f i s su r e opened, extending lengthwise with the water. p. 438.

225 C 1868 Lawson and others, A la rge f i s su r e was made i n t he high bank near Fort Point and t he 1908, shock w a s f e l t severely a t t he Fort. p. 438.

226 A 1906 Lawson and others, On Fulton S t r ee t , between Twelfth and Thirteenth Avenues, there ---a+ 1908, was m c h slumping of the s t r e e t - f i l l i n g down i n t o t he Park adjacent;

p. 232. and exactly the same s o r t o f damiige occurred on H S t r ee t , between Ninth and Fourteenth Avenues. t + They were espec ia l ly susceptible t o damage from earthquake shock, being p r ac t i c a l l y loose ear th embankments.

C 1906 Lawson and others, All driveways i n the western pa r t o f Golden Gate Park showed 1908, s ca t t e r ed narrow f i ssures . p. 233.

TABLES 5 9 143

TABLE 1 .Spee i f i c descriptions of ground failures Ln San Francisco City and County-Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t i on "re "re ra- earth- No. No. type cy quake

C 1906 Fallows, [Picture caption] CRACK I N THE EARTH. This photograph shoios a 1906, CI.BC~ in the ear th i n Golden Gate Park, San Francisco, caused by the p. 313. earthquake.

227 B 1906 Gilbert , Hmphry , At the bottom of Strawberry H i l l is a bridge crossing over Stow Sewell, and Soule, Lake. This bridge is made of concrete, and showed no signs of

@ 1907, cracking, although the banks of the lake sl ipped i n t o the water. p. 30.

A 1906 Lawson and o thers , Strawberry H i l l , i n Golden Gate Park, is a cher t knob r i s i n g 1908, abruptly i n the sand wastes. * * * p. 232 and 233. The whale periphery of the h i l l t o p was broken i n ro a s e r i e s of

concentric blocks or s teps , and t he outer ones moved down the h i l l from 2 t o 3 f e e t . The a r t i f i c i a l s tone work was badly cracked and dislodged. These phenomena indica ted t h a t the material used i n

a grading the upper slopes had s e t t l e d somewhat, with consequent rupture of the surface and wrecking of the building.

A 1906 Gilbert , Hmphre~ , The most i n t e r e s t i ng s t r uc tu r e i n Golden Gate Park i s t he cyclorama Sewell, and Soule, (PI. XXIII, A), on the top of Strawberry H i l l , b u i l t about f i f t e e n 1907, years ago. The top of t he h i l l had been leveled off i n order t o

0 p. 29 and 30. form a foundation. + * * The s e t t l i n g of the foundation of f i l l under t he v ibra t ion of the earthquake caused the s t r uc tu r e t o collapse. 7hc s l i p (PI. XXII, B) occurred p r i nc ipa l l y on the north- e a s t s i de , the movement being 4 o r 5 fee t . The pr inc ipa l crack i n t he base was about 11 inches wide, with a half- inch horizontal crack leading from it along the reenforcement. The f loor i s i n good condition, except t he pavement, which broke i n t o blocks * + * .

229 A 1906 Gilbert , Humphrey, Within the c i t y proper the reservoi r known as Lake Honda was damaged Sewell, and sou16, by the cracking of its concrete l ining. It i s reported t ha t t h i s

@ 1907, cracking was due t o the displacement of a re ta in ing wall by a s l i d ing p. 115. bank s e t i n motion by the earthquake.

A 1906 Ouryea and others, The slope, on the west s i de cons is t ing of very sandy s o i l , was 1907, supported by a re ta in ing wall which consti tuted t he s ide of the p. 249. reservoi r basin. * * * The e f f e c t o f the shack was t o rupture t h i s

@ re ta in ing wall , which f a i l e d by shearing near the bottom of the reservoi r , although i r r egu l a r cracks i n one p lace extended t o t he top of the wall.

Lake Honda Reservoir, * * * was in jured by the earthquake cracking the heavy western wall, the shock coming from the west and shaking up a sandy mountain, about 100 fee t high, causing t he slope t o s l i d e down towards t he wall.

230 C 1906 Lawson and others, Ocean Avenue, between Ingleside and t he sea, tho almost devoid of 1908, s t ruc tures , shows by the unearthing, bending, and even breaking of

> p. 231. drainage and water pipes, and by f i s su r e s i n the road and asphalt paving, a change o f i n t ens i t y from Grade C t o Grade B.

231 B 1906 Lairson and others, Near Lakeview, f a i r l y well b u i l t frame buildings on dune sand of 1908, unknown thickness were caused t o lurch and s h i f t t h e i r posit ions. p. 231.

232 B 1957 Bonilla, 1959,

Landslides occurred a t about a dozen d i f f e r en t places along the shore of Lake Merced, and most, i f no t a l l , involved a r t i f i c i a l f i l l . The width of the s l i d e s ranged from 75 t o 300 f ee t and one s e r i e s of s l i de s extended along t he lake shore for 800 fee t . The s l i d e s produced scarps t h a t were about 10 f ee t high. In many o f the s l i d e s t ha t a f fec ted the


TABLE 7.Specific descriptions of grouna failures in San Francisco City and County-Continued

Loca- Fig- Fail- Aecu- Year of Reference t ion ure ure ra- earth- No. No. type cy quake

Quotation

1957 Steinbrugge and others, 1959, p. 103.

1957 Bonilla, 1960, p. 6.

1957 Bonilla, 1960, P. 6.

1957 Bonilla, 1960, p. 6.

1957 Bonilla, 1960, P. 21, f ig . 4.

1957 Bonilla, 1960, p. 6.



highmy along the lake shore the pavement was r o t a t ed so t ha t it dipped away &rn the scarp r a t h e r than toward t he scarp as is normal i n slump- type landslides. Very l i t t l e debr i s from these s l i d e s was v i s i b l e above-the l eve l of the lake a few hours a f t e r the earthquake. These two conditions sumor t the i n t e ro r e t a t i on t h a t the s l i d ing was i n the nature o f a flow 'a;ld t ha t the m s e r i a l spread out on the Take bottom. The material i n the scarps was mostly uncompacted a r t i f i c i a l f i l l made up o f clean, loose, well-sorted sand which, because it was on the shore of the lake, must have been saturated. This s l i d ing probably was of the type ca l l ed sand-flow, which r e s u l t s from spontaneous l iquefac t ion of sand.

At t he Lake Merced Pump Sta t ion i n San Francisco, a f i l l e d area s e t t l e d 4 t o 6 inches, severing a 12-inch pipe from the s ta t ion .

Table 1. Landslide number 11; slump i n s o i l ; 60 f e e t long and 150 f ee t wide.

Table 1. Landslide number 10; slump i n s o i l ; 100 fee t long and 100 f ee t wide. Also Landslide number 9; slump i n s o i l ; 60 fee t long and 125 f ee t wide.

Table 1. Landslide number 8; slump i n s o i l and sand flow; 100 fee t long and 800 f e e t wide and consisted o f several coalesced s l ides .

S l ide 8, shown on figure 4, probably s t a r t ed as a sand flow, but removal of support by the flow r e su l t ed i n slump f a i l u r e near the head of the landslide.

Table 1. Landslide number 7; sand floir and s l m p i n s o i l ; 80 f e e t long and 225 f ee t wide.

A + . . sudden movement of the ground occurred on the west s ide o f Merced Lake, whereby a la rge sec t ion of t he slope sank toward and i n to the lake, and a port ion o f the bottom of the lake was l i f t e d above the surface by the deformations1 ro t a t i on o f the collapsed ground.

J m t south o f the bridge across Lake Merced, a sand-bar was forced up out of the lake, from water t ha t was previously 6 or 8 f e e t deep. This ba r i s p a r a l l e l t o the west bank o f the lake, and has a d i rec- t i on almost due north and south. This was probably caused by the same th ing t h a t wrecked the bridge; t h a t i s , the displacement and s e t t l i n g of t h e west bank o f the lake a t the time o f the earthquake.

Table 1. Landslide number 4; slump i n s o i l ; 110 f ee t long and 200 f e e t wide.


Lake Merced.--About 6 miles north o f Mussel Rock, where t he hlerced beds disappear under aeolian sands, the disturbance seems t o have been qu i t e violent . An o ld r a i l r oad t r e s t l e , t h a t crosses the northern end of Lake Merced i n the narrowest place, was badly wrecked. This

TABLES F-9 145

TABLE 7 .Spec i f i c descriptions of ground failures in San Francisco City and Comty-Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on u r e ure ra- earth- NO. No. type cy quake

Quotation

bridge was broken i n two places, and t he intermediate piece was out of l i ne with both ends. The d i rec t ion of the o f f s e t s was very nearly due nor th and south. A t one bre& the west piece was shoved 12 o r 14 f ee t pas t the o ther section. The west end o f the intermediate piece f a i l ed t o join the sec t ion a t t he west bank by 6-ar 7 fee t . The west sec t ion t h a t remained with the bank was from 4 t o 5 f e e t lower ve r t i - c a l l y than the intermediate piece. The t r e s t l e was old , b u i l t of heavy timbers on a sharp curve, and not i n use, which w i l l i n p a r t account for i t s destruction. The swaying of t h i s bridge destroyed a sec t ion of it 50 t o 60 f ee t long. On the h i l l s i d e where t h i s t r e s t l e reaches the west bank of the lake, cracks p a r a l l e l t o the shore l i ne Suggest the cause of the destruction of t he bridge. The displacements here are l a rge r than any along the main f a u l t l i n e , and it i s apparent- l y en t i r e l y loca l , due t o the s l ipp ing and s e t t l i n g of the west bank of t he lake.

Table 1. Landslide number 3; slump i n s o i l ; 100 f e e t long and 100 f ee t wide.

1957 Bonilla, Table 1. Landslide number 2; debris s l i d e ; 100 f e e t long and 150 1960, f e e t wide. p. 6.

1957 Bonilla, Table 1. Landslide number 1; debr is s l i de ; 75 f ee t long and 80 1960, fee t wide. p. 6.

+ A 1957 Bonilla, 0 1960,

A 1957 Bonilla, 1960, p. 21.

In addit ion t o the f a i l u r e s along the roadway a t the shore of Lake Merced, the f a i l u r e of the a r t i f i c i a l f i l l a t the north end of t he foot-bridge crossing the north arm of the lake a l so was probably caused by sudden l iquefac t ion of sand. Some of t he s l i d e s along Lake Merced were of the slump-earthflow type and displayed a backward ro t a t i on of the component blocks. These s l i d e s may have been caused by removal of support by sudden l iquefaction of sand a t the foot of the slope.

Table 1. Landslide number 5; sand flow; 70 f ee t long and 80 f ee t wide. Landslide number 6; slump i n s o i l and earthflow; 125 fee t long and 120 f ee t wide.

S l ide 5 i s an example of t h i s type o f landslide. I t severed the a r t i f i c i a l embankment north o f the footbridge t ha t crosses the north arm of Lake Merced, as shown on f igure 3. The enact dimensions of the s l i d e deposit could not be determined

because it was under water but about 80 f ee t of the embankment was ~ ~ ~~~

destroyed. The vegatat ian displaced by the s l i d e i s v i s i b l e on a i r photos taken four months a f t e r t he s l i de . Measurements made on t he photos show tha t the vegetation on the s ides of the embankment moved a t l e a s t 70 fee t both eastward and westriard from the or ig ina l shore- l i ne of t he embankment. The material v i s i b l e i n the north end of the embankment was a r t i f i c i a l f i l l composed of clean sand, and as a la rge deposit of dune sand i s found a short distance north of the s i t e , it is probable t ha t a l l of t he embankment was clean well-sorted sand obtained from the dunes. The slope o f the embankment above water was on t he order of Zoo, and under water was presumably less . The earthquake v ibra t ions probably l iquef ied t he s taurared sand at the

base of the embankment and the unsupported embankment collapsed and spread over t he lake bottom.

1906 Lawson and others, On Ocean Avenue and X S t ree t , near where the former ou t l e t of Lake 1908, Merced flowed, f i s su r e s were developed i n the s t r e e t and i n t he p. 241. sands on e i t he r , s i de , and water was squeezed out so as pa r t l y t o

flood the roadway. Drain pipes were unearthed and bent o r twisted.


TABLE ? .Spec i f i c descriptions of ground failures in San Francisco City and County-Continued

Ldca- Fig- Fa i l - Accu- t i on "re ure ra- No. No. type cy

Year of Reference earthquake

1852 Townley and Allen, 1939, p. 28.

1852 ~oulc / , Gihon, and Nisbet, 1854, p. 408.

I906 Schusrler , 1906, p. 9.



1906 Seattle Post- Intelligencer, 1906C.

Quotation

1852 November 22. 11 p.m. VIII. Near San Francisco. Severe shock eight miles southeast (?) of San Francisco. Next morning a f i s su r e ha l f a mile wide and three hundred yards long was discovered, through which the waters of Lake hlerced were flowing t o t he sea.

1852. Novenber 22 to 24. San Francisco Peninsula. This shock was severe 8 miles southwest o f San Francisco. Apparently, considerable f i s su r i ng occurred from Lake Merced t o the sea.

1852. November 22; 11 p. m.; VIII. Severe shock e ight miles south- e a s t of San Francisco. Next morning a f i s su r e ha l f a mile wide and three hundred yards long was discovered, through which the waters of Lake Merced were flowing t o the sea.

November 23d.--The waters of Lake La Mercede, i n the v i c in i t y of the c i t y , and irhicll cover several hundred acres, sank about t h i r t y fee t . Shor t ly before midnight of t h i s day, a shock l i ke t ha t o f an earthquake was f e l t by p a r t i e s res id ing near the place; and the following oorning it was discovered t ha t a great channel between the lake and the sea had been opened, through a broad and high sand bank, during the night , by which the waters had found a way and been discharged.

* * The most probable conjecture i s , t h a t the excessive r a in s o f the season had simply forced open a passage through the broad and loose sand-bank from the lake t o the ocean. Formerly t he lake had no v i s i b l e ou t l e t whatever; and i t s waters had insensibly been kept about the same leve l t *

* * * vest and southwest from Lake Nerced * r r the ou t l e t , or ocean end, of our br ick Lake Merced drainage tunnel was completely covered up and closed by a la rge s l i de .

Forty-eight Avenue, between K and N S t r e e t s , i s a d i s t r i c t underlain by deep sand where extensive grading operations were undoubtedly necessary t o convert an area o f sand-dunes i n to s t r e e t s and building l o t s . Here small, s ubs t an t i a l frame dwellings were sh i f t ed bodily from 1 t o 2 f e e t out o f pos i t ion , and t he s t r e e t s were s l i g h t l y d is - located.

* * * Forty-eight Avenue between K and L S t r ee t s , within a few hundred f e e t of the ocean * r * the sand i n our basement ra i sed from 1 foot t o 18 inches. A wide and long 3-foot depression wai ra i sed level . Our l o t , which was 120 f e e t deep, was shorted a t l e a s t a foot , which was shown by the fo ld ing of t he fence. E l ec t r i c - l i gh t poles i n the s t r e e t i n f ront of us, which were i n the sand, were thmwn down north, eas t , south, and west. There was a f i s su r e f o r about a block, between Forty- seventh and Forty-eighth Avenues, about 3 f e e t wide and 6 o r 8 inches deep, which was of course i n the sand. There were a l so o ther blow- holes i n the sand, which emitted water and sulfurous odors.

There i s one place within p i s t o l shot of ruined San Francisco t ha t t he earthquake did not touch, t ha t d id not lose a chimey o r f e e l a tremor--Alcatraz i s land . Despite t h s f a c t t ha t t he i s land i s covered with brick buildings, br ick f o r t s , and brick chimneys, not a brick was loosened, not crack made, not a quiver f e l t .

TABLES &9

TABLE 8 .Spec i f i c descriptions of ground failures in the,north bay counties region

Location number i s assigned t o each reported ground-failure s i t e . Corresponding numbers are found on p l a t e 4. Figure number re fers t o f igure in t h i s report showing damage described under "Quotation" column. Fa i lure type i s indicated by t he folloriing symbols. Corresponding symbols are found on p l a t e 4.

Hi l l s ide landslides including ro t a t i ona l slumps, ... ... River s t re tches with extensively f i ssured flood block glides, debris avalanches, and rockfa l l s

... pla ins ; pa t te rn indica tes s t re tches of r i v e r a f fec ted and not width of disturbed zone

@ Streambank landslides including ro t a t i ona l slumps and s o i l f a l l s 0 Sand boi l s

+ Lateral spread Absence of ground f a i l u r e noted

Ground set t lement Miscellaneous e f f ec t s

Ground cracks not c l e a r l y associated with land- * Arrows showing extent of area af fec ted . s l ides , l a t e r a l spreads, set t lement or Symbol shows f a i l u r e type primary f a u l t movements

Accuracy with which f a i l u r e s i t e s can be located i s given as follows: A, a s i t e t h a t can be accurately relocated; B, a s i t e t ha t can be re loca ted t o within a few kilometers and probably could be located more accurately with fu r t he r inves- t iga t ion; C, a s i t e where the information i s insuf f ic ien t t o allow prec ise location.

P la te numbers in the "Reference" c o l m r e f e r t o p la tes in t he o r i g ina l source material .

Loca- Fig- Fail- Accu- Year of Reference Quotation t ion ure w e ra- earth- NO. No. type cy quake

249 C 1906 Jordan, @ 1907,

p. 33.

A t Sobrante, in Contra Costa County, e a s t of San Francisco Bay there are la rge slumps o r cracks i n t he ear th .

250 C 1906 SaZinas D d l y Indez, The Santa Fe's Condition. r r r The railway bridges and ra i lyards x 1 9 0 6 ~ . a t Pinole sank two f ee t .

251 B 1906 LawSon and others, Mare Island.--The earthquake was much l e s s severe than t ha t of 1898, 1908, which wrecked many o f t he Government buildings i n the navy-yard. p. 212. None of the Government buildings was wrecked t h i s time, nor was t h e

damage a t a l l serious except in t he case o f two or three new bhild- ings recent ly erected on t he "made" land near t he water-front. Here t h e ground was thrown in to v io len t undulations, and t he buildings were so twisted t h a t about $2,000 worth of r epa i r s had t o be made. On t h i s s o f t ground t he br ick walls were cracked * * r . In t he case o f the o lder buildings r e s t i ng on hard ground, no cracks were formed, nor any in jury reported.

B 1898 Townley and Allen, 1898 March 30. 11:43 p.m. VIII. Mare Island. San Pablo Bay. 1939, This earthquake wrought such damage a t Mare Island Navy Yard t ha t p. 105. it may properly be known as t he Mare Island earthquake. + * *

Admiral H. W. Lyon, U.S.N., has furnished t he following information: " r * * The violence of t he shock was grea ter than any shock previously experienced on t h i s is land, as f a r as can be learned from the o ldes t inhabi tan ts .

"A de ta i led account of t he damages done is s e t for th i n a repor t t o t he commandant, dated April 5, 1898.

252 B 1906 Lawson and others, The r a i l r oad t rack ea s t o f Martinez, near 8a11'5 Head O i l Works, + 1908, was thrown 3 inches out of alignment t o t he north. Many cracks p. 310. occurred i n the embankment on both s ides of t he track. A series of

5 small t ransverse waves was found i n t he embankment about 0.5 mile west of Peyton Sta t ion . The d is tance between c r e s t s was about 10 t o 15 f ee t ; amplitude estimated a t 3 inches. This embankment l i e s in f l a t marshy land. A small r a i l m a d bridge near Avo" Sta t ion was thrown 4 inches toward t he ea s t abutment, but it had been repaired a t t he time of t he v i s i t .


TABLE 8.Speeific descriptions of ground failures in the north bay counties region-Continued

Loea- Fig- Fail- Aecu- Year of Reference t ion ure "re ra- earth- NO. NO. type cy quake

Quotation

253 C 1906 S m Frmzcisco Stocton, April 30.--It was discovered to-day t ha t i n t he v i c in i t y Chronicle, of Woodbridge the Mokelumne River has f a l l en twelve f ee t , the bed of 1906b. t he r i v e r having dropped from the e f f ec t s of t he recent earthquake.

The stream had been ca rmine a l o t o f water when it was noticed t ha t the r i v e r was s t e ad i i y Fall ing, contrary t o a l l precedent. The people could hardly believe t h e i r eyes. They watched t he r i v e r recede fo r a day and made an investigation, with the r e s u l t t h a t the bed was found t o be almost twelve f e e t lower than before. As the water way has been s t e ad i l y f i l l i n g up each year with s i l t

from the upper port ion o f the r i v e r , farmers along t h a t stream are highly pleased with the change, s ince it can carry f a r more water than heretofore, and not endanger t h e i r lands on e i t he r s i de of it. Another incident o f t he earthquake i s the drying up o f Tracy lake,

i n t he northwestern p a r t of San Joaquin county. Ever since the earthquake t he water has been decreasing a t a rap id r a t e , and a t present it is almost on a leve l with t he Mokelumne r i ve r . Whether o r no t there is a crack i n i t s bed, o r an underground

passage connecting t he lake with the r i ve r , i s no t known, but a t the r a t e t he lake has been f a l l i n g it w i l l soon be as low as the r i v e r . The benef i t i n both instances w i l l be appreciated by farmers.

C 1857 Sacrmnento Age, we have information of severe e f f ec t s of the earthquake along the 1857. l i ne o f t he lower Srocktan Road. Below Benson's Ferry the waters of

the hlokelumne r i v e r much swelled by recent ra ins , were thrown over t h e banks, leaving rhe bed of the stream almost bare. Houses were shaken v io len t ly , destroying a r t i c l e s of glassware and over turning furniture. Limbs were broken o f f from t r e e s and t he t r e e s i n some instances s e t t l e d down trio o r t h r ee f ee t i n to t he ground. The inhabitants o f t ha t sec t ion were t e r m r s t r icken , whi l s t dwnb brutes appeared t o be paralyzed.

254 C 1906 Duryea and others, A t one point on the marsh between Benecia and Suisun, on the Southern X 1907, Pac i f ic , the set t lement was 11 f t . ; a t another point , 5 ft . These

p. 258. were nearly ve r t i c a l .

C 1906 Ransome, On the north shore of Suisun Bay pa r t of the t rack o f the Southern X 1906, Pac i f ic , l a i d on marsh, subsided several f e e t .

p. 294.

X C 1906 Davison, Three miles of railway have sunk out of s i gh t between Suisan and 1906, Benecia * * . p. 25416.

C 1906 Engineering News, Farther e a s t [of Oakland and ~ e r k e l e y ] the Southern Pac i f i c Co. 1906. suf fered much disturbance o f i t s railway l i ne s * * . A sec t ion a f x t r a ck between Oakland and Sacramento sank several fee t ; a railway

bridge over the San Joaquin s e t t l e d some inches [see loc. 1821.

C 1906 The Evening Post, Effect of Shock Bezween Susan [s ic ] City and Benecia. A telegram 1906e. from Sacramento t o the Western Union Telegraph Company's o f f i c e in

I t h i s c i t y , repor t s r ha t th ree miles of r a i l r oad sank out of s i gh t as a r e s u l t of t he earthquake between Suisan [s ic ] City and Benecia, i n Solano County, and a l l wires were taken with it. * * reported sinking of a three-mile sec t ion o f the r a i l r oad company's t racks between Suisun and Benecia, which are on the d i r ec t l i ne betireen Sacramento and San Francisco. The road crosses some low land a t the point where i t s t racks are reported sunk. The location of t h i s sinking of the ear th i s about t h i r t y miles from San Francisco.

C 1906 The Evening Bee, Trains Brought Back. Trains which had been dispatched f o r San 1906a. Francisco ear ly t h i s morning had t o be brought back, and they were

sent t o the Bay City by the Lathrop route. It was a t the spot where the t r a ck disappeared t ha t the r a i l r oad

company had so much t rouble l a s t Winter, when a loaded passenger t r a i n came near going out of s i gh t . A grea t army of men was then s e t a t work t o f i l l up t he s ink . The task was a most d i f f i c u l t one,

TABLES 5-9 149

TABLE 8 ,Spee i f i c descriptions of gfound failures in the north bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference t i on ure ure ra- earth- No. NO. type cy quake

Quotation

C 1906 Los A n g e t e s D a i t y Times, 1906C.

M

B 1906 Pubtic Ledger, 1906.

X

c 1906 The E u e n i n g Bee, 1906b.

as enormous timbers which were thrown i n t o the hole quickly sank from view, and t he t ra in loads o f ear th dumped i n disappeared l i k e snow in a f i e r ce sunshine. But t he engineers f i n a l l y mastered the s i t ua t i on , and a f t e r a week's time t r a i n s were sent over the route again. I t i s now feared t h a t i t w i l l take several weeks' time t o r epa i r t he present collapse, and i n the meantime a l l t r a i n s w i l l be sen t by t h e s t o c t o n [sic] route. EARTH CRACKED OPEN. There are great crevasses on each s ide of the

t rack throueh the Suisun marshes and it is r e ~ o r t e d t ha t a mea t " 0

ocean of water has flowed over t h e lowlands between Suisun and Benecia. ENGINE SINKS I N EARTH. A shor t d i s tance below Suisun, a Southern

Pac i f ic switch engine sank i n to the ground f o r a d is tance of three f ee t , not f a r from where t he t r a ck disappeared.

Sacramento, April 18.--A shor t time a f t e r the b ig shock came a message from Suisun, Solano county, saying t h a t a long sec t ion of t rack had disappeared from view. I t was learned l a t e r t ha t , i n one place between Sprig and Teal s t a t i ons , i n the Suisun marshes, for a distance of one mile and a ha l f , the t rack had sunk down three t o s i x fee t , and a t anorher point nearly one thousand f ee t of t rack ,rent out. * * * The t rack sunk by the earthquake is near the place where a loaded passenger t r a i n came near going out of Bight. * * * There are great crevices on each s ide of the t r a ck through the Suisun marshes, and it i s reported t ha t a great ocean o f water has flowed over the lowlands between Suisun and Benecia. A shor t d i s tance below Suisun, a Southern Pac i f ic switch engine

sank i n to the ground fo r a distance of three f ee t , not f a r from where the t racks disappeared.

Sacramento, April 18.--A shor t time a f t e r the shock o f the earthquake a message came from Suisun, Solano County, saying t h a t a long sec t ion of t r a ck had disappeared fmm view. One place between Sprig and Teal s t a t i ons i n the Suisun marshes fo r a distance o f one mile and a ha l f t he t rack had sunk three t o s i x f e e t , and a t another point near 1000 f ee t o f t rack went out.

Sacramento, Cal., April 1%- * r * I t was learned thar between Sprig and Teal s t a t i ons fo r a distance of one mile and a ha l f the t rack had sunk three t o s i n f e e t . A t another point nearly a thousand f e e t of track sank from s ight .

The Southern Pac i f ic Company repaired i t s t racks beyond Suisun yesterday afternoon and t r a i n s are now running d i r ec t t o San Francisco. The loca l o f f i c i a l s s t a t e t ha t tho rumor t o t he e f f ec t t h a t the t racks had gone out of s i gh t was not so, and it took but two or three carloads of d i r t t o leve l t he tracks. This was done by 2:30 yesterday afternoon and l a s t night t r a i n s were running through t o Oakland on schedule time.

255 C 1892 Holden, 1892. April 19; Vacaville. * * The ground was f i ssured i n many 1898. places. p. 174 and 176.

256 8 1892 Holden, 1892. April 20; Winters. A t Winters there have been developed a 1898, number of f i s su r e s i n the ear th , water has been e jec ted , gas has p. 187. escaped, and the bed of the creek has been f i l l e d up fo r a distance

6' of over 70 yards. Many of the wells have been f i l l e d up by the collapse of t h e walls .

C 1892 Holden, 1892. April 19; \?inters; Zh. 50m. a. m. On Putah Creek, ha l f a 1898, mile west of Winters, a phenomenon was witnessed by a young man p. 178 and 179. named Fred Will is , who was r i d ing pa s t a t the time o f the big

shake. There seemed t o be an explosion, and t he water was throw? from the creek t o a distance of 20 f e e t on e i t h e r bank. Then follow-

E] ed a h iss ing sound as o f gas escaping. A t daylight several f i s su r e s

150 HISTORIC GROUND FAILURES I N NORTHERN CALIFORNIA TRIGGERED BY EARTHQUAKES

TABLE 8 .Spee i f i e descriptions of ground failures in the north bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference t i on ure ure ra- earth- No. No. type cy quake

Quotation

6 C 1892 Coffman, 1973,

0 p. 160.

C 1892 Holden, 1898, p. 195 and 196.

C 1892 Holden, 0 1898,

p. 195 and 197. 0

were found i n the bed of the creek and i n the roadway and f i e l d s adjoining. On each s ide of the creek where t he explosion took place t he banks caved i n , the landslides being 75 f e e t i n length and 12 f ee t deep.

1892. April 19; Winters; * * near the town the bank of Putah Creek, ten f ee t wide, caved i n , and along the bottom of the creek f o r a great distance r en t s were made by the shocks. West of here about three miles, an acre of ground s l i d i n t o the creek.

1892. ApriZ 19. * * * Fissures were found i n the bed of Putah Creek, 112 mile west of Ivinters, and i n the adjoining roadway and f i e l d s ; banks of the creek were caved i n .

1892. April 21; Winters. * * r The r a i l r oad t rack i s a l l r i gh t , and te legraphic communication has been uninterrupted, but there are many nasty cracks and f i s su r e s i n t he roadways, and dr iv ing i s dangerous.

1892. April 21; Winters. * r The sand bars i n Putah Creek near Winters opened and from the f i s su r e s t he water spurted high up on t he banks. In some places the creek became dry, i n others i t changed t o a t o r r en t . The banks caved i n some places and almost dammed the stream.

1892. April 19; i * * Up the Berryessa road the passage i s blocked by immense bowlders [sic] , some weighing several tons , which were thrown down the h i l l s i d e s i n t o the road. I t i s near t h i s point where the r en t s i n the road were noticed.

258 C 1892 Holden, 1892. April 21; r * * It was reported t ha t severa l bo i l ing springs 1898, had burs t from the f o o t h i l l s on the north and west and were flowing p. 195 and 197. s teadi ly .

1892. April 19; Esparto. + The ear th opened i n severa l places between here and Capay.

260 A 1906 Duryea and others, The draw-bridge a t Black Point, over Pe t a lma Creek, on the Sonoma 1907, Branch of t he Cal i forn ia Northwestern, was open a t the time o f the

4 p. 259. earthquake, and was thrown off i ts center 2 f t . t o t he ea s t and 1 f t . t o t he north. This is a s t e e l s t r uc tu r e , 220 f t . long, on four i ron caissons, f i l l e d with concrete, on p i l e foundations.

261 B 1906 Lawson and o thers , The buildings of t he Dickson ranch, 2.5 miles south of Olema, are 1908, about 0.25 mile e a s t of the f au l t - t r a ce , standing on a h i l l s i d e p. 192. presumably on firm ground. They near ly a l l s l i d southwest--that i s ,

downhill and toward t he f a u l t .

262 C 1906 Lawson and others, Bedrock cracks occurred a t many poin ts within the R i f t , usually 1908, appearing as branches from the f a u l t s . They were seen a l so a t a p. 75. number of poin ts west of the R i f t , t h e i r d i s t r i bu t i on ,reaching t o

the ocean i n the v i c i n i t y o f Point Reyes, ten miles from the f au l t - t race . A t t h e more remote poin ts they were qu i t e small, often barely d iscern ib le , and no system o f arrangement was discovered. They are pecul ia r lv ~ rominen t alone the summit of the r idee cons t i t u t i ne the ;outhwestkG r i m of the miin Bolinas-Tomales t ro igh . This summit was v i s i t ed on four l i ne s of road [ locs. 265, 275; 2761 and a t each l o c a l i t y ccnspicuous cracks were found. On the road from Inverness t o Point Reyes Post Office [ loc. 2761, about a mile i n a d i r e c t l i n e

TABLES &9 151

TABLE 8.Specif ic descriptions of ground failures in the north bay counties region-Continued

Laca- Fig- Fail- Accu- Year of Reference t i on ure ure ra- carth- No. No. type cy quake

Quotation

from Tomales Bay, a crack was t raced f o r more than 800 f ee t . I t s general t rend is e a s t and west, but i t s course i s not s t r a i gh t a d it has a branch diverging a t 45'. Along t h i s crack there i s a horizontal throw of from 2 t o 6 inches, the south s ide having moved westward with reference t o the north s ide .

C 1906 Lawson and o thers , In t h i s region [Bear valley] I saw only a fen. cracks other than 1908, road-cracks, and t he road-cracks were unimportant. p. 195.

Lawscn and others 1908, p. 192.

Mr. Payne J. Sha f t e r ' s place i s near the v i l l age of Olema. The f au l t - t r a ce i s close t o the house and o ther buildings. These stand on a bed of alluvium which i s probably supported by bedrock a t a shor t d i s tance below the surface. In t he barnyard men were milking, and were thrown v io len t ly t o the ground, along with the ca t t l e . The buildings were much damaged. During the earthquake a cow f e l l i n to the fault-crack and the ear th closed i n o n h e r , so tha t only the t a i l remained v is ib le . At the time of my v i s i t the t a i l had disappeared, being eaten by dogs, but there was abundant testimony t o subs tan t ia te the statement. As t he f au l t - t r a ce i n t h a t neighborhood showed no cracks large enough t o receive a cow, i t would appear t h a t during t he production o f the f a u l t there was a temporary par t ing of the ioalls. [Some have d iscredi ted t h i s repor t . See Earthquake Engineering Research I n s t i t u t e Newsletter, v . 9, no. 1, p. 103.1

264 B 1906 Lairson and others, 0Lema.--The v i l l age of Olema i s about 0.5 mile e a s t of the f au l t - 1908, t r a ce and a t the edge of the R i f t be l t , the grea ter pa r t being p. 193. included within the Ri f t . The residence o f Mr. Pease, stand'ing on

alluvium, was sh i f t ed south about 2 f e e t , f a l l i n g from i t s supports. r r + A neighboring piece o f a l l u v i a l land bordering Olema Creek

I sank about 2 f e e t .

265 B 1906 Lawson and others, On Mount \%ittenberg there are two bedrock cracks. One of these 1908, crosses the northeastern spur of the peak near i t s junction with the p. 75. main c res t . I t s t rend is approximately northwest and southeast and

a t one point it margins a fault-sag. As it assumes i n one place the r idge phase o f the fault-crop, I i n f e r t h a t it has horizontal displacement. On the opposite s i de of t he main c r e s t is a crack which was t raced fo r about 1,000 f ee t . I t s general course i s northwest- southeast , but i t i s not s t r a i g h t and exhibits a ve r t i c a l throw of 1 or 2 f e e t t o the southwest. A t one point it touches a fault-sag. Between these two long cracks a group of shor t cracks occurred, with s im i l a r trend, on a knob cons t i tu t ing a port ion of the main divide. [These cracks may have been caused by secondary fault ing.]

266 58 C 1906 Lawsan and others, They [cracks i n alluvium] were seen from the t r a i n i n the bottom- 1908, land o f Papemi l l [Lagunitas] Creek within a mile o f Point Reyes p. 74. Stat ion. They were a l so seen i n the d e l t a o f Papermill Creek, i n

the bottom-land of Olema Creek near Olema, and i n t he d e l t a of Pine Gulch Creek. They were seen i n t he bottom-lands and de l t a s of a number of small creeks en ter ing Tomales Bay from the west between Inverness and t he head of the bay. Other l o c a l i t i e s were t i d a l

p l a t e 498 marshes a t t he head o f Bolinas Lagoon (p la te 4981, a t the head of Tomales Bay, and i n small e s t ua r i e s ncar Inverness. They irere seen in the marsh of Bear Valley Creek near where t he stream jo ins Papemi l l Creek; and a road embankment crossing t ha t marsh was elaborately cracked and fau l ted t h r u much of i t s extent .

C 1906 Lawson and others, [Picture caption] Faults i n road embankment, southwest of Point 1908, Reyes S ta t ion . Fault- trace i s beyond fence. Ground lurched toward

59 p l a t e 50B. marsh of Bear Valley Creek. G. K. G.



Loca- Fig- Fa i l - Accu- Year of Reference t i on ure ure ra- earth- NO. NO. t s e cy quake

Quotat ion

A 1906 Jordan, 1907, + p. 19.

Paper M i l l Creek [ ~ a ~ u n i t a s ] runs pas t t he same v i l l age [Point Reyes Stat ion], * * * . The two banks of the stream were forced toward each o ther so t h a t the length of t he bridge was shortened by about s i n f e e t and the bridge was correspondingly humped a t i t s nor th end, an arch about s i x f e e t high being forced up.

B 1906 Duryea and others, * r * a highway bridge across a creek t r i bu t a ry t o Tomales Bay, near 1907, Point Reyes S ta t ion on t he North Shore Railway, i n Marin County, and p. 270, within l e s s than 2 miles of the f a u l t l i ne . * * * p l a t e 54. The bridge, or ig ina l ly , had e ight panels, i t s t o t a l length being

appmximately 120 f t . It i s located i n a d i rec t ion nearly north and south. The abutments are of p i l e s and timber. The e f f ec t of the

X earthquake was t o s e t t l e t he north abutment some 2 o r 3 f t . , and move + it southivard s o much t h a t , i n patching up t he s t r uc tu r e temporarily,

the north end panel was not u t i l i z e d as pa r t of the span * * r . B 1906 Duryea and o thers , Portions of t he t r e s t l e over Lagunitas Creek, about a mile from

1907, Point Reyes, were throrm en t i r e l y o f f t he p i l e s , t he p i l e s themselves + p. 258. being moved down stream.

C 1906 Lawson and others, Beyond Garcia t he creek has several reaches of a l l uv i a l bottom, and 1908, some of these were 50 badly shaken t ha t the railway embankments and p. 196. t r e s t l e s had t o be repaired. Railiray t r a f f i c t o Point Reyes [from

Sausali ta] was interrupted fo r about 10 days.

267 C 1906 Lawsan and others, [Picture caption] Road embankment broken by shaking of s o f t ground 1908, beneath. Southwest o f Point Reyes S ta t ion and 10 rods from f au l t -

60 p l a t e SOA. t r a ce . G. X. G.




1906 Duryea and others, 1907, P. 258.

1906 lveatherbe, 1906, p. 402.

1906 Lauson and others, 1908, p. 78 and 79.

The road running southwest from Point Reyes S ta t ion and crossing the valley a t the head of Papermill Creek [Lagunitas] de l t a was o f f s e t 20 f e e t [by fault ing]. r t The embankment of the road res ted on marshy ground s o so f t t ha t a port ion o f the embankment sank in to it, and material o f t h i s character was i n o ther l o c a l i t i e s demonstrably sh i f ted .

I dmve a few miles nor th and e a s t from the [Point Reyes] s t a t i on , over a high t e r r ace separating the upland from the bay a t the eas t .

* A few cracks were seen i n t he ground, but they were much smaller and l e s s numerous than a t a s im i l a r d is tance on the appo- s i t e s ide o f t he f au l t .

The "fills" across t h e arms o f Tamales Bay generally sank from 2 t o 8 f e e t . The 1,000-yard f i l l about 2 miles north of Point Reyes S ta t ion sank from 6 t o 8 f e e t ; as did the next f i l l , which i s some 500 f e e t long. In one o r two instances the pile-supported bridge i n the middle o f the f i l l remained a t grade. * * The bottom of the bay in these arms i s usually sand.

On the North Shore, about 2 m i l e s north of Point Reyes, t he road, or ig ina l ly , had been constructed with p i l e t r e s t l e s across several arms of Tornales Bar: these t r e s t l e s had been f i l l e d about 15 years ago, t he road-bed being about 8 f t . above ordinary high t ide. . Two of these embankments, 2 200 f t . and 900 ft. long, respec t ive ly , sank u n t i l the water a t high t i d e washed over t he r a i l s .

Along the coast , t h e railway was grea t ly disturbed, invariably sinking in t he low swampy land except where b u i l t on p i l ing .

A la rge port ion of t he de l t a was throim by the earthquake i n to gentle undulations, the difference in height between the swells and hol1ou.s being usually l e s s than a foot . The chief evidence

TABLES 5 9

TABLE 8.Speeif ic descriptions of ground failures in +e north bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t i on w e "re ra- earth- No. NO. type cy quake

61 p l a t e 548, of t h i s is found in t he d i s t r i bu t i on of pools a t low t i de , and where 62 p l a t e 558, vegetat ion i s present t he evidence from pools is supplemented by

p l a t e 56A. tha t from the condition o f the p lan ts . The undulations were not elongate and were not found t o have a systematic r e l a t i on t o the f a u l t . Men the t i d a l mud was f i r s t seen a f t e r the earthquake, it was

observed t o be covered with r idges and troughs. (P la te 548.) This corrugation was gradually smooti;ed out by tho ac t ion of the waves (p la tes 558 and 56A). so t h a t a t the expirat ion of a year i t s en- pression was l a rge ly l o s t , tho a few of t he la rger r idges could still be traced. and much of the ~ l a i n re ta ined a oa t t e rn imorest on it bv t he r idging. It is probable t h a t t he e n t i r e t r a c t of t i d a l mud was thus affected, a l t h o t he r idges were not seen on the area lying nearest t o the e a s t shore. That area did not come under observation u n t i l a f t e r the spr ing floods o f 1907, and i t was then overspread by a f resh deposit brought by Papemi l l Creek [Lagunitas Creek]. The r idges varied somewhat i n height , the amplitude from c r e s t t o trough ranging from 1 t o 3 f e e t and possibly more. Their general t rend was p a r a l l e l t o t he fau l t - t race , but there were notable encep- t i an s , and aver small t r a c t s the d i rec t ion was even a t r i gh t angles t o it. In some cases, where the minor r idges were pa r a l l e l , there were l a rge r r idges t ravers ing them obliquely. Fig. 25 reproduces a sketch map o f the l oca l i t y showing the grea tes t complexity. [See f ig . 25 a t end of tables.] So f a r as t he broad undulation o f the t i d e lands were seen i n conjunction with the r idging, the grea ter r idges were on t he sirel ls and not in the holloxrs.

A 1906 Lawsan and others, 1908. p. 79 and 80, p l a t e 558, p l a t e 57A, p l a t e 578, p l a t e 58.

[see t e n t , "North bay counties region," paragraph 5, f o r addit ional discussion of f a i l u r e mechanism and d i rec t ion o f movement.] There was a l so a horizontal s h i f t i n g of mud aver a considerable area. Residents fami l ia r with depths of water i n the v i c in i t y o f Inverness s t a t e d t ha t t he earthquake caused a decided shoaling along the coast , but tha t the r e l a t i on of water leve ls t o firm ground was unchanged. I t was a lso s t a t e d t h a t a channel which had ex is ted pa r a l l e l t o the west share of the bay, and t o irhich p i e r s had been run, was ab l i t e - ra ted by the earthquake. The shoaling might have been caused e i t h e r by an u p l i f t of the bottom o r by a sh i f t i ng of the mud of which it is composed toward t he shore. That t he second of these explanations is cor rec t seems t o be sham by the following f ac t s . At various places along the shore, from Inverness t o a point 1.5

miles southirard, the t i d a l mud seemed t o be crowded against the f irmer ground a t the shore, being pushed up in a r idge, as shown i n the accompanying photograph. (Plate 558.) Two p i e r s a t Inverness, l i g h t wooden s t ruc tures , r e s t i ng on p i l e s and extending out several hundred f e e t from the shore, were telescoped. (Figs. 26 and 27.) [See f i g s . 26 and 27 a t end of t ab l e s . ] In the case of Mar t ine l l i ' s p i e r the telescoping was sho!un by the inc l ina t ion given t o p i l e s a t t he landward and bayward ends, from which it appears t h a t the ground i n which t he p i l e s were s e t was crowded together, so t ha t the founda- t ion of t he p i e r was shorrened, while the superstructure r e s i s t ed shortening. The res i s tance was temporary only, for before the agi- t a t i on ceased the p i e r was bmken i n two; and the inc l ina t ion of the p i l e s i s supposed t o have been given during the ear ly stages of the tremor. Coincident with the movement of t he ground toward t he share, there was a movement pa r a l l e l t o the shore irhich had the e f fec t of o f f s e t t i ng t he outer knd of the p i e r about 25 f e e t toward the northwest. (P la te 57A.) The r e su l t an t of the two movements, o r t he ac tua l d i rec t ion of s h i f t i n g of the mud, was westward, or a l i t t l e t o the north of vest : and t he maximum s h i f t i n r i n t ha t d i rec t ion was not l e s s than 30'feet . Rather more than ha l f the p i e r , the pa r t nearer the shore, remained s t r a i g h t and suffered ch ief ly from the s l an t i ng of i t s supporting p i les . This pa r t s tands on the submerged de l t a o f a small creek, and i t s foundation appears not t o have sh i f ted . The outer pa r t suffered most violence near the junction o f t he s h i f t i n g mud with t he f irmer gmund, being t he r e 50 completely wrecked t h a t its platform f e l l . The photograph and map represent it a f t e r r epa i r s had been made.


TABLE 8.Speeif ie descriptions of ground foilures in the north bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t i on "re "re ra- earth- No. No. type cy quake

In the case o f Bailey's p i e r , which is beyond the de l t a , the most important telescoping, as shown by the s lan t ing of p i l e s ( f ig . 27), was close t o the shorc, and near ly the whole s t r uc tu r e was t rans- ported by the s h i f t i n g mud. I t a l so sagged more than a foot j u s t beyond the middle, and the a t t i t udes o f the associated p i l e s suggest t ha t the sag corresponds t o a holloir made i n t he surface of the mud. The p i e r was so badly broken as t o requi re extensive r epa i r s , and i n making these repa i rs Mr. Bailey used the o ld material f o r f looring, but found t h a t he had enough lumber remaining f o r 12 f e e t of f looring, so t h a t he infer red a shortening of 12 f ee t . The whole p i e r was sh i f t ed t o the northwest, being given a curved form (p la tes 578 and 58), and the maximum amount of sh i f t i ng i n t ha t d i rec t ion was a t l e a s t 25 f ee t , a l t ho the circumstances did not admit of accurate measurement. Combining the movement toward the shore with the o f f s e t pa r a l l e l t o the shore, it i s probable t ha t the d i rec t ion and the maximum amount o f s h i f t i n g were about the same as i n the case of the Mar t ine l l i p i e r .

I t i s a notable fea ture of t h i s displacement t ha t the disturbed material moved uo the s h o e instead of dom. so t ha t the t r an s f e r was not only independent o f gravity but opposed t o it. The phenomenon, therefore, does not f a l l i n the same category with landslides, and i f properly in te rpre ted it may throw l i gh t on the mechanics of

A 1906 Gilbert , Humphrey, e Sewell, and Soulk,

1908, p. 8 and 9,

62 p l a t e 7A, 61 p l a t e 8A.

B 1906 Lawson and others, 1908, p. 194, p l a t e 458.

the earthq;ake pulses. The area t h ru which the s h i f t i n g o f the mud took place is inde ter -

minate. I t a f fec ted a shoal o a r a l l e l t o the irest shore of the bay and more than a mile long. A; t h e p i e r s t he width of the affected region was a t l e a s t 400 f ee t and may have been much more. The reported c los ing of t he chnnel suggests 700 or 800 f e e t as a minimum estimate, but the outer margin o f the a f fec ted area was probably beneath the water of the bay and outside the range of observation. The firmer p a r t of t he Papemi l l [ ~ a g u n i t a s ] de l t a appeared not t a be included i n the movement. Al l of the area know t o be affected l i e s southwest of t he fau l t - t race , which i n t ha t neighborhood i s about 2,000 f e e t from the shore.

[BY the same author as t he above quotat ion.1 r r- * an extensive s h i f t i n g of mud on the bottom o f Tomales Bay. At the head of tho bay and thence f o r a d is tance o f several miles northwestward t he s o f t mud was moved bodily westward. I t no t only descended from the northeast shore, 50 as t o cause deeper water, but ascended toward the southwest shore, c rea t ing a broad s h o d (PI. VII). The horizontal change o f pos i t ion near the southwest shore was i n places more than 25 f ee t , and the ve r t i c a l change as much as 2 f e e t . As the ascending movement can not be ascribed t o gravity, it must be re fer red t o the earthquake, even though the way i n which the ear th waves produced the e f f e c t i s not evident. The l oca l i t y is adjacent t o the f a u l t t r a ce , the pos i t ion o f which i s along the bottom of the bay, e a s t of the shoal. The i l l u s t r a t i o n s may requi re a few words of explanation. The upper

view of P1. V I I looks northward from the southwest shore of the bay. Tide being low, the newly formed shoal or mud bank is broadly exposed, but the receeding t i d e has l e f t a lane o f water t o mark the separa- t ion of the mud bank from the f irmer ground t h a t withstood the quak- ing. Immediately a f t e r the earthqu&e the mud was r i g id , as i n the t r a c t shorn i n PI. V I I , A; but before t he view of PI. VII, A, was taken (April 28, 1906) the surface had been l a rge ly smoothed by the ac t ion of wind waves. A s i ng l e r idge which escaped t h a t ac t ion appears a t the l e f t in the upper view o f PI. VII and i n t he foreground of t he lower view.

Inverness i s a v i l l age of s m e r residences on and near t he southwest shore o f Tomales Bay. The upland o f the peninsula there c lose ly approaches the bay. The v i l l age occupies two narrow va l leys normal t o the shore, and a mesa between them. I t s s i t e i s within the R i f t , and both va l leys and mesa were traversed by many cracks, of which some had the character of branch f au l t s . A l l the houses were of wood. About ha l f o f them were sh i f t ed on t h e i r foundations. To a ce r t a i n

TABLES 5 9 155

TABLE 8 . S p e c i f i e descriptions of ground failures in the north bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference t i on "re "re ra- earth- No. NO. type cy quake

Quotation

Lawson and others, 1908, p l a t e SIB.

Lawson and others, 1908, P. 195.



Lawson and o the r s , 1908, p. 194.

Lawson and others, 1908, p l a t e 51A.

Lawson and o thers , 1908, p l a t e 538.



extent the d i rec t ion of sh i f i i ng was determined by the slopes of the ground, the houses moving downhill; but where t ha t f a c to r did not control , the movement was toward the west o r southwest. In one Instance I noted a southwestward movement of several fee t uphil l .

[picture caption] Roadside crack a mile southeast of Inverness. G. K. G.

Sunshine Ranch and Vicinity.--I drove t o the s u m i t of the r idge southwest of the head of Tomales Bay, f ind ing abundant and s t rong road-cracks a l l the way t o the c r e s t , which i s about 1.5 mile* from the fau l t - t race . There were a l so a number of landslides i n t h i s region, and a considerable number of t r e e s were broken o r uprooted.

On the west s ide of the main r idge west o f the head of Tomales Bay there occurred two wet s l i de s . In one case a h i l l s i d e bog was loosened from the slope on which i t rosted and descended as a flow of m d t o a canyon bottom 100 or 200 f e e t below. I n Llre oihcr case the ear th beneath a wet meadow i n a r a the r s teep canyon flowed down the canyon for about 0.5 mile, overpowering t r e e s on i t s way and leaving a deposit 15 or 20 f ee t deep i n places. This was the la rges t individual s l i d e observed.

In a l l the cases mentioned the conditions were such t h a t s l i de s would have taken place a t some time had t he earthquake not occurred.

On the next road t o t he southward [from loc. 2761 a group of cracks llas seen a t a point a mile from the shore o f Tomales Bay. These cracks occur on a c r e s t t rending northwest and southeast , and t h e i r t rend makes a small angle with t h a t of the c r e s t . The arrangement of the cracks suggests horizontal shear, but no de f i n i t e observation was made on t h i s point . They extend for severa l hundred f e e t a t l e a s t , but were not t raced out.

Inverness to Point Reyes Ligkt-house.--For the f i r s t 2 miles of t r ave l , covering a r i gh t - l i ne d is tance o f about 1.5 miles, road- cracks were numerous and often large. There were a l so numerous small f a l l s o f ear th from the road c l i f f s . Beyond t h a t point there was a rapid f a l l i n g o f f of such evidence, and tho road-cracks were frequently seen they were a i l small. [See loc. 262.1 [Some of these cracks may have been caused by secondary fau l t ing . ]

[picture caption] Roadside crack 2 miles west of f a u l t , between Inverness and Point Reyes P. 0. G. K. G.

[picture caption] Landslide from road -c l i f f about two miles west of Inverness. Sl ide occurred a t time o f earthquake. G. K. G.

A t the U. S . Life Saving Stat ion, on the coast 3 or 4 miles from the light-house * * * t h e f i l l e d ground about the house s e t t l e d several inches.

A t Marshall 's a hote l and a s t ab l e b u i l t oq the r e s t s ide of the track and on underpinning, r e s t i ng i n the t i d a l f l a t , vent e a s i l y and gently i n to the bay. The occupants o f the ho t e l did not r e a l i z e t ha t the ho t e l had fa l len . but a t f i r s t thoueht t he water had r isen. [Photographic evidence i n ' t he Branner ~01lee;ion a t Stanford suggests this'lnay have been s t r uc tu r a l f a i l u r e , t ha t the building simply s l i d o f f its p i les . ]


TABLE i -Specif ic descriptions of ground failures in the north bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference t ion ure ure ra- earth- No. No. Type cy quake

Quotation

279 X B 1906 Lawson and others, Ju s t above Hamlet a trestle-work which had been f i l l e d i n s e t t l e d , 1908, leaving the trestle-work some 2 f ee t above. The bottom of t he bay

in these arms is usually sand. At Hamlet qui te an extensive lands l ide has s t a r t e d i n the h i l l s i d e

above the track. The r a i l m a d cu t is i n o ld rock, and the arch of the head of t he s l i d e is some 70 f ee t above the track. The country wagon road has been car r ied away by the s l i d e f o r possibly 100 yards.

C 1906 Lawson and others, At the mouth of Tomales Bay there are two points pro jec t ing west- 1908, ward from the ea s t shore, and both of these, according t o the obser- P. 65, vations of Prof .R. S. Holway, are cros t by t he fault- trace. * * p l a t e 1428. On each s ide of the crack [ fau l t ] are c ra te r - l ike depressions, some

of them being double or overlapping. M r . Keegan, t he ommer of Oil lon's Beach, reported t ha t these c r a t e r l e t s were numerous and d i s t i nc t . In some instances a great deal of sand and water had been ejected. Others are reported on the southwest s i de of the f au l t - t race , from which t he b e l t containing then extends some 70 fee t . The c r a t e r l e t s vary i n s i z e up t o 6 f e e t i n diameter and i t i s reported t ha t on the day a f t e r the earthquake the water trhich stood i n them could not be bottomed by a f i sh ing pole.

B 1906 Lawson and others, la ear Salmon Creek] + * a small mud-flat extends f m n the sea up 0 1908, t o the road. Curious mounds o f mud, shaped l i ke truncated cones, were

p. 191, thrown up by the earthquake. Subsequent examination showed t ha t the p l a t e 142A. l i n e of t he earthquake f i s su r e must have pas t near t h i s spot.

282 C 1906 Lawson and others, There are qu i t e a number of cracks i n the f l a t valley-bottom adja- 1908, cent [ to Valley Ford, Sonama Comty]. A landslide of several hundred'

+ p. 199. yards i n length but of very s l i g h t movement is found on the s ide of the valley d i r ec t l y e a s t of town. The s l i d e has moved j u s t enough t o make a furmw-like r idge on the lower s ide and has developed cracks on t h e upper side. Other small s l i d e s occur i n the v ic in i ty .

283 B 1906 Duryea and others, Trest2es.--Trestles over marshes suffered more o r l e s s from the + 1907, movement of the so f t material i n t o which the p i l e s were driven. The

p. 258. most serious damage was a t Fallons, on the North Shore, where a t r e s t l e , 600 f t . long and 70 f t . high, was thrown down. This t r e s t l e was constructed of framed bents on p i l e s .

B 1906 Duryea and others, Trest2es.--The damage t o t r e s t l e s was small, except on the North 1907, Shore Railroad, where a t r e s t l e of framed bents on p i l e s , 600 f t . p. 214 and 215. long and 70 f t . high, was thrown down, and port ions of another

t r e s t l e were thrown en t i r e l y o f f t he p i l e s , the p i l e s themselves 0 being moved down stream. These t r e s t l e s were across s o f t ground,

and near the fau l t - l ine .

284 B 1906 Larison and others, Tomtes, Mmin County. * * Cracks were reported i n the s t r e e t 1908, and near the depot. Ju s t north of the depot there was an extensive + p. 198, landslide along the ra i l road , which threw one t rack over t he other. p l a t e 129A. (Plate 129A.)

B 1906 Weatherbe, A t Tomales, about e ight miles inland, the [ ra i l road] l i n e f a r over + 1906, 1,000 f t . was car r ied down a gent le slope t o the ea s t f o r a d is tance p. 402. of 50 f t . A l l these disturbances are exac t ly along t he fau l ted

l ine , now well defined, though t he movement and ac t ion i n each of the cases above noted has been en t i r e l y l oca l and following the configuration of the ground. L i t t l e evidence, therefore, can be deduced pointing t o a de f i n i t e regional movement i n any cer ta in d i rec t ion . Buildings an ground r e s t i ng on long p i l e s seem undisturbed and the worst e f f ec t s are noted on or toward swampy grolmd.

TABLES 5-9 157

TABLE 8 .Spec i f i c descriptions of ground failures in the north bay counties region-Continued

Loca- Fig- Fail- Aecu- Year of Reference t i o n ure ure ra- earth- No. No. type cy quake

Quotation

1906 Lawson and others, At Freeman's, 3 miles northeast of Tomales, a la rge landslide was 1908, caused by the shock. (P la te 129B.) p. 198, p l a t e 1298.

1906 Lawson and others, No cracks are reported i n the low a l l uv i a l land around t he lagoons 1908, nor i n Chileno Valley. p. 199.

1906 Lawson and others, A t J u r ' s ranch, about 2.5 miles northwest [of petalma], 3 cracks 1908, with a very s l i g h t dropping of small blocks between them, are p. 206. reported. A temporary flow o f water was reported from a crack by

the road.

1906 Lawson and o thers , Small cracks were reported on the road about 4 miles [north] from 1908, Pe ta lma. D. 206.

1906 Lawson and o thers , A t r i p was made out on the Pe t a lma road t o the Copeland d i s t r i c t 1908, ~ch001 , then t o Cotate, t o t he Durham d i s t r i c t school, and back t o p. 203. Santa Rosa. . . I could hear o f no cracks i n t he ground i n the

va l ley ; and i n only one place, about 2 miles from Santa Rosa, on the Petal- road, could I hear of any increase o r change i n the flow of springs.

1906 Lawson and o thers , Near Stony Point school-house, about 9 miles out [north fmm 1908, Petalma], 19 cracks across t h e road were reported by the teacher. p. 206.

1906 Lawson and o thers , A t Nason's ranch there i s s l ands l ide of the bank of the lagoon 1908, 100 yards o r more i n length. Four miles [south] from Scbastopol is p. 206. another lands l ide a t Davis' ranch, where a house was thrown from i t s

underpinning.

1906 Lawson and o thers , Cracks were reported a t Hansen's and several places. There i s a 1908, d i s t i n c t increase i n cracks and landslides i n the approach t o p. 206. Sebastopol [from Petalma].

1906 Lawson and others, [G. X. Gilbert] On the Burbank farm a small landslide occurred, 1908, a layer o f moist s a i l only a few f e e t i n thickness moving down the 0. 205. slooe. introducing bends i n various l i ne s of cu l t iva ted e l an t s . I

s a i a n o t h e r feat"& o f t h i s s o r t on an adjacent farm, a& was t o l d of others which I did not v i s i t .

1906 Lawson and o thers , [David S t a r r Jordan] A t Burbank's farm, 0.5 mile west o f Sebastopol, 1908, I noted these things: In t he l o t adjoining, t o the south, tho s o i l p. 204. being clayey, there i s a la rge crack running northwest znd southeast ,

o r nearly so, and, according t o Burbank, 0.25 mile long. It runs thru t he f i e l d s and weeds, and was very d i s t i n c t on Augcst 6. The end of t h i s crack comes up against the sandy h i l l occupied by M r . Burbank's orchard. The crack does not show i r s e l f i n the h i l l , but an t he ea s t s ide of the l i n e o f t he crack the raws of t r e e s and p lan ts were sh i f ted toward the south--or, i f you p r e f e r it, those on the west s ide toivard t he north--2 or 3 fee t . A well of W. Burbmk's, sunk i n the sandy ground, i s bodily shifted, without being injured, along with the raws of p lan ts between which it is place=. No crack appears a t the surface i n Burbank's ground, but on the o ther s ide of the h i l l s , t o the north o f it, I was t o ld the crack reappears.


TABLE 8.Specific descriptions of ground failures in the north bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference Quotation t ion ure ure ra- e a n h - No. NO. type cy quake

B 1906 Jordan, There are d i s t i n c t t races of great disturbance across Burbank's 1907, famous orchard a t Sebastapol, but it i s not c l e a r t ha t i n any of p. 32 and 33. these t he underlying rock i s r e a l l y broken. Here on a slope l i ne s + of f r u i t t r e e s were sh i f t ed , a r icl l was moved bodily three or four

f e e t , and a crack about one fourth mile long extended acmss a neighboring f i e l d , i ts d i rec t ion p a r a l l e l with t ha t o f the Tomales rift. Other s i r n ~ l a r cracks open a t i n t e rva l s on the road toward Point Delgada.

294 C 1906 Larison and others, Near t he top of Taylor H i l l , i n a marshy place, there was a land- 1908, s l i d e , the ear th having s l i d on a clayey bottom. P. 203.

La~vson and others, The most marked physiographic e f f e c t s i n t he v i c in i t y of S m t a Rosa 1908, were found near t h i s [main Santa Rosa] cemetery. J u s t north of the p. 201. cemetery h i l l i s a swampy depression. Part of t h i s s e t t l e d 2 o r 3

fee t with the formation of a crack along the s ide , extending for some 200 f e e t . The cemetery is on a low h i l l which the sexton repor ts as being sand, gravel , and clay, but which shows a rocky outcrop, on the eas te rn s ide , near t he base. A crack an inch or more wide was found on t h e northern end o f t he h i l l near the swamp mentioned above. This crack could not be followed fo r more than 100 f ee t , a l t ho the sexton repor ts t h a t a t f i r s t i t extended 2 o r 3 times t ha t distance. A small ra te r -p ipe on t he southern pa r t of the h i l l , running north and south, was pulled apar t . A pipe on t he northern pa r t of the h i l l , running eas t and west, i s reported by Mr. Weaver as pulled apar t abbut 4 inches. On t he southwest of the cemetery h i l l , M r . John Livsey repor ts t ha t severa l f ine cracks formed acmss the road running north and south, and t h a t the dust was blown away near the edges of the tracks.

Jordan, San Jo se ' s water works, l i ke t h a t o f Santa Rosa, was not in jured; 1907, i ts sewers a l so were l e f t i n t a c t , showing t h a t there was no unequal p. 188. displacement of t h e ground.

Lawson and others, A teamster working i n the creek j u s t south o f the tannery [F and 1908, 2nd St5.1 says t ha t he noticed cracks an inch wide and severa l rods p. 201. long a few days a f t e r the shock. He "thinks t he cracks were not

there before."

Moore, About 1 112 miles from the water tower i n t h a t c i t y [Santa Rosa] 1906, there i s a crack i n t he ground about 3 f t . wide a t the top and about p. 527. 20 f t . deep. A few hundred f ee t from the tower a man driving across

the f i e l d i n a buggy yesterday (April 28) s t ruck an impassable morass, where before he had driven many times, and before discovering it had driven so f a r i n t o it t h a t t he horse was with d i f f i c u l t y got out.

Cloud and others, The e a r t h - f i l l approaches t o t he Highway 12 bridge over Highway 101 1970, subsided several inches i n response t o the shaking. 'The only orher p. 54. known bridge damage was repeated pounding a t the construction jo in t3

i n t he sidewalks over t h e abutments of the Brookwoad Avenue bridge a t Matanzas Creek. No major landslides were t r iggered by t he shock. A few minor rock

f a l l s were found along steep road cuts and severa l f i s su r e s were formed i n a marshy area and on steep slopes. Some of these cracks may have been generated by lands l ide ac t ion (see a r t i c l e on Surface Breaks, page 60).

B 1969 Cloud and others, Adjacent t o such pr inc ipa l drainage courses as the Santa Rosa and 1970, Matanzas Creeks, ground shaking and r e su l t an t cracking was par t icu- p. 60 and 61. l a r l y apparent. * *

On the c r e s t o f "moving mountain" nor th of t he c i t y along De Vera Way, a crack developed which passed through a house; t he crack showed evidence o f v e r t i c a l movement. This crack appeared t o be r e l a t ed t o the lands l ide scarps immediately adjacent where severa l houses were destroyed a few years ago.

TABLES %9 159

TABLE 8 .Spec i f i c descriptions of ground failures in the north bay counties region-Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on "re "re ra- earth- NO. NO. type cy quake

Quotation

~p

A search fo r f resh ground ruptures along the Radgers Creek f au l t was made but none Here found. * * A few boulders from s teep mad cuts i n t h i s area [of Crane Canyon Road] were dislodged but no s ign of f resh landslides were detected o ther than a small slump beneath a pa r t of the road bounded by a s teep embankment. The most widespread cracking was found in the IOOF Cemetery on

the north s ide of town. [See Lawson and o thers , 1908, p. 201 above, for 1906 comparison.] Here, along Poppy Drive, the asphalt paving was crossed by several dozen fresh cracks oriented both northwest across the road and a l so northeast , p a r a l l e l t o the road. The area l i e s i n a low depression c lose to a swamp. The adjacent ground immediately t o the north ires a lso observed t o be cracked, but t he or ien ta t ion of the cracks appeared t o be random. The cracks i n Poppy Drive, which opened from 1/16 t o 114 inch, were pulled apar t perpendicular t o t he crack faces. There was no apparent l a t e r a l m r i o n component or ve r t i c a l component, nor did t he cracks form any en echelon o r o the r regular pattern. The cracks appeared i n a zone o f f i l l e d ground adjacent t o the swamp; thus they appeared t o be the r e su l t o f heavy shaking of marshy subs t ra ta . * * * The day following t he October 1 quake, f resh i r r egu l a r cracks 118 t o 114 inch wide were noted i n t he hard-packed dry d i r t roads i n the cent ra l pa r t o f the Rural Cemetery; however, these were not or ien ted along any preferred trend. S t r s e t s i n the immediate v i c i n i t y north and south of the cemetery area were carefu l ly examined f o r cracks bur no fresh cracks i n the asphalt were found.

296 B 1906 Laivson and others, The only o ther physiogrsphic e f f e c t s folmd were a t t he County 1908, Hospital , a l i t t l e more than a mile north of the cemetery. Here

x p. 201. low ground a t t h e foot of a small h i l l sank f o r some 2 f ee t and springs were formed. These springs were reported as s t i l l running the l a s t o f July.

B 1906 Lawson and others, In the v i c in i t y o f t he Sonoma County Hospital, the s o i l i s very 1908, l i k e the Santa Rosa s o i l * r a t t he hospi ta l a marshy place along

0 p. 203. the creek s l i p t toward the creek and the flow o f springs was grea t ly increased.

297 C 1906 Lawsan and others, A few loca l s l i d e s on t he south s ide o f Mount St . Helena loere con- 1908. f ined t o t he alluvium.

298 a A 1906 Lawson and others, Mmc- SZide, 6 m i t e s easter7.g from HeaZdsburg (R. S. Holiray) 1908, This s l i d e i s an t he north s i de of a r idge t ha t runs i n an ea s t e r l y p. 184 and 185, d i rec t ion and t h a t is a t t h i s point from 225 t o 300 f e e t above the p la te 124A, bed of Maacama Creek, which runs along tho foot o f the north slope. p l a t e 1248. Mr. Hugh Simpson, whose house i s j u s t beyond t he foot of the s l i de ,

s t a t e s t ha t the e n t i r e s l i d e took place a t the i n s t an t o f the earthquake. The s l i d e i s about 0.125 mile wide a t the top and about 0.5 mile long. The rock i s a very l i g h t , porous, volcanic t u f f and seems t o be f r e e from water. A s l icken-sided wall on t he ea s t shows a very smooth surface i n s p i t e o f the s o f t rack. S t r l a e near the top run N. 13' W. with a p i tch o f about 24'. The s l i d e seems t o have taken o f f some of the t op of t he r idge ; t h a t i s , it s t a r t e d a few f e e t down the south slope of the r idge, cut its way t h ru a f i r fores t and dammed btaacama Creek with rocks and t r e e s . Either two successive s l i d e s occurred o r e l s e the upper pa r t of the moving mass was ar res ted p a r t way down, f o r a bank with the vegetation of t he top r e s t s across t he s l i d e about one-third o f the way dom. (See p l a t e 124A. B.) This s l i d e was subsequently v i s i t ed by M r . G . K . Gilbert , who con-

t r i bu t e s t he following supplementary note:

A t Maacarna schoolhouse, I saw t h e la rge landslide aescribed by Professor Holway. The rocks involved are i n layers , with a dip of about 30' i n t he d i rec t ion of the s l i de . It i s therefore



Loca- Fig- Fail- Accu- Year of Reference quotat ion t i on ure u r e ra- earth- No, No. type cy quake

probable t ha t t he s l i d e was pa r t l y determined by the dip, tho it seems t o have been fur ther determined by the erosion of the va l ley of hlaacama Creek. * * * [Mr. Stimson] and o thers mentioned numerous cracks in the bottom lands a mile t o the north, and espec ia l ly i n the bottom lands of the Russian River a t i t s neighboring la rge bend.

A 1906 Lawson and others, Maacama s l i de , 6 miles e a s t of Healdsburg. (p ia te 124A, 8.1 The s l i d e 1908, i s about 0.125 mile wide a t t he top, and 0.5 mile long. The rock i s a p. 390. s t r a t i f i e d volcanic tuf f , and t he slip was down the dip of the beds.

The avalanche cut its way t h ru a f i r fores t and dammed Maacama Creek.

299 C 1906 Lawson and others, Cracks i n the Russian River Ftood-ptain (R. S. Holriay1.--Cracks have . . . 1908, been observed a t i n t e rva l s i n t he a l l uv i a l banks of the Russian River ... . . . p. 184, from near i t s mouth t o Alexander Valley, 5 o r 6 miles northeast of

p l a t e 13% Healdsburg. These cracks are sometimes 100 yards i n length and from p l a t e 1398. a few inches t o 2 f e e t i n width. Sometimes near the bank there w i l l

be a deep f a u l t 5 t o 6 f e e t i n width and 100 fee t long, as shown i n the photograph of t he crack a t Monte Rio. The d i rec t ion of the cracks i s usually pa r a l l e l t o t he bank of t he r i v e r o r the bank of some small t r ibu tary . A t Duncan Mills the cracks ran north and south above the bridge and near ly e a s t and west j u s t below the bend of the r i ve r . A t Monte Rio they are ea s t and west. In,Alenander Valley they run north and south, while a mile o r two below some are found nearly e a s t and west running up a small t r i bu t a ry .

C 1906 Lawson and others, Heatdsburg, Sorvrm County. * * * Along t he bottom-land of the 1908, ~ u s s i a n ~ i v e r , cracks from an inch t o a foot i n width opened a t

severa l places. * r Fissures i n the creek bed near the t o m [~ea ldsburg] are i n evidence.

Water was t h r o w out and continued t o flow f o r severa l hours, a t f i r s t with some considerable force; then it gradually diminished and f i na l l y disappeared.

C 1906 Lawson and others, Along t he creek and r i ve r bottoms the ea r t h was f i ssured and water 0 1908, ivas forced up which, i n some instances, flooded the orchards.

p. 184.

B 1906 Duryea and others, The bridges over the Russian River, a t Healdsburg, and a t Bohemia, + 1907, an the Cal i forn ia Northwestern, were both sh i f t ed s l i g h t l y on t he p. 259. p i e r s a t one end.

B 1906 Lawson and others, Alexander Valley i s p a r t o f the Russian River Valley ly ing ea s t of 1908, Lytton Springs. The main bridge across the Russian River was wrecked, p. 184. the trestle-work p a r t g o ~ n g down. The bridge was old and was t o have

been r e b u i l t t h i s year. At the ea s t end of t he bridge cracks cross the road, northwest t o southeast , p a r a l l e l t o the r i v e r bank. These cracks appear a t i n t e rva l s northwesterly, a t l e a s t as f a r as t he ranch o f Rev. E. 8. Ifare, about a mile up the r i ve r . The cracks vary from a few inches t o aver a foot i n width, and are sometimes 200 t o 300 fee t long, roughly p a r a l l e l t o the r i ve r . Mr. Ware s t a t e s t h a t t he shock threw the r i v e r water upon t he sandbars t o such an extent t ha t he found f i sh there during t he day., Other cracks are reported

n a mile o r two northward. Subsidence frequently occurs where t he cracks are near t he bank.

C 1906 Lawson and others, mincm's M Z Z s (J. Parmeter).--On the Russian River, when fisherman 1908, t r i e d t o seine f i s h a f t e r the earthquake o f April 18, t h e i r ne t s were p. 191. torn t o pieces by snags, e t c . , where there had formerly been no

obstruction. Large t r e e s t h a t had been buried i n the bed of the r i v e r were l i f t e d up by the convulsion, while o ther t r e e s vanished t h a t had been i n s ight . Low places i n t he r i v e r bed were made high and vice verso. The bottom o f the r i v e r appears t o have dropt 2 f e e t a l l along by

Duncan's Mills fo r 2 miles; and a t the mouth of t he r i v e r , where there used t o be water 12 o r 14 f ee t deep, there i s now only 2 f e e t , and a r i f f l e till boats can hardly cross, f o r a length of almost a mile. For over a mile there i s now a s t rong current , where there

TABLES 5 9 161


Loca- Fig- Fa i l - Accu-. Year of Refarenee Quotation t i on ure ure ra- earth- No. No, type cy quake

used t o be quiet water with very l i t t l e cur ren t . A man who was by the r i ve r , near Monte Rio, when the earthquake occurred, t o ld the Parmeters t ha t he saw t h e muddy bottom of the r i v e r r i s e t o the surface, and t he water ran off over t he banks. The bottom was t h e highest where t he ivater had been 8 o r 10 f e e t deep; then it s e t t l e d - back. A road and fence moved 10 fee t . On t he a the r s ide of Russian River from Duncan's Mills, 200 o r 250 f e e t back from the stream, t he earthquake made many holes t h ru which black sand and water blew up.'

0 Such blow-holes were made a l l along t h i s r i ve r . Between the r i v e r and the ruined hote l a t Duncan's is an i r regular crack abbut 20 f ee t wide, 80 f e e t long, and 1.5 t o 4 f e e t deep, with a blow-hole 4.5 fee t wide and 2 f ee t deep where coarse r i v e r gravel came up.

(R. S. Ho1way.)-- * * [ A t Duncan's Mills] Along t he r i v e r there !?as several cracks i n the alluvium.

300 C 1906 Lawson and others, From Paint Arena southward t o Fort Rosg, t he c l i f f s are.low, being -a+ 1908, for t he most pa r t not i n excess o f 100 f ee t . Earth-avalanches were

p. 387. nevertheless o f common occurrence along t h i s s t r e t ch of coast . South of Fort Ross t o Bodega Head t he c l i f f s are again, as f a r as the mouth of t he Russian River, several hundred f e e t high and very steep. Here again earth-avalanches were extensive. The rocks along t h i s e n t i r e s t r e t ch o f coast from Cape Mendocino t o Bodega Head are preva i l ing ly sandstones and shales.

301 C 1906 Lawson and others, Several s l i d e s were seen about 3 miles south o f t he Fort [ ~ o r t ROSS].

1908, One of these was of g r e a t s i z e , being between 300 and 400 f ee t in p. 190 and 191. height . These are evidently old s l i de s , and the amount of material

brought down by t he recent earthquake, though la rge , is ins igni f icant compared ivith t he s i z e of the scar.

A 1906 Lawson and others, GunZnZo VaZZeq.--At Casey's ranch * * . The ranch stands on t he 1908, e a s t edge of t he r idge , west of the Gualala River, and t he f a u l t runs p. 180 and 181, along t he mountain s i de several hundred f e e t below it. The slope i s f ig . 14. a steel, one. densely timbered exceot for i t s uner oort ion. Landslides . . .. .

were found over a la rge pa r t o f i t s surface, but only i n a few iso la ted spots had they resu l ted in t he complete removal o f the or ig ina l surface, and t he fores t growing thereon; so t ha t a view from across t he r i v e r revealed no appreciable changes i n the landscape. The slopes ea s t of the r i v e r were s imi la r ly a f fec ted and the f a l l en timber produced a tangle not unlike t ha t o f extensive windfalls . In a t l e a s t two places the r i v e r was temporarily dammed up by s l i d e s from both slopes meeting in t he stream bed, but none of these dams was of noteworthy s i z e . [See f i g . 14 a t end of tables.]

303 A 1906 Lawson and others, East of Stewart 's Point the bridge aver t he South Fork of the Gualala 0 1908, River (p la te 6901 was damaged by t he slumping of t he r i v e r t e r r ace on

p. 180, which its south end r e s t s . It was subjected t o a strong longitudinal , p l a t e 690. compressive s t r e s s , which r e su l t ed i n a s l i g h t upward buckling of the

bridge f l oo r near t he southern end, and mafked bending and twis t ing of t he tension rods i n the 2 southernmst panels. The supports a t t he

x. south end furthermore appear t o have s e t t l e d 13 inches, causing t he f l oo r and t h e l a s t panel t o assume a marked inc l ina t ion . A hundred yards eas t o f t he wagon bridge is an older, d i lap ida ted one, whose f loor has been removed fo r some time. I t s r icke ty aspect and crooked- ness render it an unsa t i s fac tory object for study in t h i s connection. There i s , however, clear evidence of t he slumping o f t he te r race a t i t s south end, i n a manner s imi la r t o t h a t a t t he new bridge; ye t t he old bridge appears t o have stood t he compressive s t r e s s b e t t e r than t he new, and i t s south end has merely overridden [sic] t he displaced masses of t he te r race . On both s ides o f t he sharp bend o f t he r i v e r eas t of t he two bridges

are extensive landslides, making a clean sweep down the mountain s ide . The s l i d e on tho north s i de completely blocked t he iragon road and was being removed a t t he time of t he v i s i t (May 12). It i s of such height and steepness as t o menace the road a t t h i s point with renewed s l i d ing i n fu ture , espec ia l ly during wet weather.


TABLE 8 ,Spec i f i c descriptions of ground failures in the north bay counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference t ion ure ure ra- earth- No. No. type cy quake

Quotation

304 C 1906 Lawson and others, Annapolis, S o m m County (G. W. Fiscus).--Buildings were destroyed • 1908, and bridges wrecked i n t h i s neighborhmd; landslides occurred and

p. 180. the waters of the Gualala River were thrown out 50 and 60 fee t on a mavel bar. The r i v e r rose 12 o r 14 inches i n a few hours a f t e r th; shock. * * *

In several places along the l i n e o f the f a u l t f i ssure , t he ear th has opened $0 as t o allow gravel t o f a l l i n t o the cracks. I n o ther cases water and sand were shot out o f the openings, the sang remaining.

305 B 1906 Lawson and others, GunlaZa, Mendocino County.--The wagon bridge over the Gualala River, 1908, south of the town, was ser ious ly damaged. I t cons is t s of a t russed p. 179, three-span s t r uc tu r e 500 f ee t long, with a wooden appraoch of s imi la r p l a t e 68C. length b u i l t on t r e s t l e s 20 f ee t high t h ru the svampy bottam-lands on

the south side. This approach collapsed completely, t he t r e s t l e s being thrown f l a t and carrying with them the south end of the main span. The l a t t e r , hoirever, did not leave i t s nor them abutments and appears otherwise undamaged. It i s considered safe t o t r a v e l over, a l tho the bridge is now s teeply inc l ined t o the south. (See p l a t e 68C.)

306 C 1906 Larison and others, A number of landslides blocked the wagon road and r a i l r oad t rack 1908, north of the r iver . A pa r t i cu l a r l y extensive one occurred nor th of p. 180. the j ~ m c t i a n of t h e branches of the Gwla la , burying the tracks under

many tons of rock and loose dkbris.

307 66 B 1906 La!uson and o thers , Farther up, between the l m b e r camp and Hutton's ranch, extensive !a 1908, landslides occurred, ch ief ly on the ea s t s ide , wiping out t he wagon

p. 177. mad which was graded along the mountain slopes. Immediately north of Huttan's ranch, a la rge lands l ide plowed i n to a grain f i e l d , producing a s e r i e s o f billolry wrinkles i n t he s o f t a l l uv i a l material . The outermost r idge has a steep front about 8 f e e t high and seems t o have been t h ru s t hor izonta l ly over the leve l surface o f the f i e l d . The frontage of t he s l i d e is f u l l y 400 f ee t .

308 C 1906 Lawson and others, On the south s i de o f Point Arena harbor, l a rge masses of rock s l i d 1908, down t o the beach. Small rock s l i d e s took place a l l along t he coast p. 177. i n t h i s neighborhwd.

C 1906 Lawsan and others, [Point ~ r e n a ] In many cases houses dr i f ted away and l e l t parches 1908, standing in t h e i r o l d location. On t he creek-bottoms many small

0 p. 179. cracks or f i s su r e s appear, t h r u which f ine slate-colored sand has been forced t o t he surface, forming cones.

309 B 1906 Lawson and others, One mile south of Kelseyvil le and half a mile t o the west, a t t he 1908, place of Mr. McLauglilin on t he Lower Lake county road, a crack was p. 188. found i n t he alluvium out of which gas escaped, burning upon ignl -

t ion. About one mile north are gas wells i n the same kind of rock, t he gas being obtained by boring t o a depth of 165 f ee t .

310 B 1906 Lawson and others, About 3.75 miles south of Kelseyvil le on t he road t o Lower Lake, a t 1908, the ranch of M r . M. E. D. Bates, is a crack varying i n width from p. 188. 1 t o 6 inches. I t cmsses the road about 200 fee t below the house.

A t t h e r i e h t of t he road m i n e south it crosses the creek and can be seen no f i r t h e r . At rhe ; e f t o f the road it parses up the h i l l

TABLES C-9 163

TABLE 8.4'pecific descriptions of ground failures in the north bay counties region--Continued

Loca- Fig- Fail- Accu- Year of Reference quotat ion t ion "re "re ra- earth- No. No. type cy quake

toward Uncle Sam Mountain [~t. ~ a n o c t i l f o r about a mile, but is not .continuous. Near the road two small t r e e s standing on the crack have been pa r t l y uprooted and a fence post has been t h m m out en t i re ly . The rock thru which the crack passes is alluvium and a loose, uncon- so l ida ted conglomerate. I t apparently does not pass t h r u the hard Franciscan rocks. In places there are as many as 10 pa r a l l e l cracks, separated by in te rva ls of 5 t o 10 fee t , which could be traced fo r only shor t distances. On t he r i g h t s i de of the road, about 100 f e e t south o f t he cracks, s tands a schoolhouse. I t has been s l i g h t l y t i l t e d t o the south.

C 1962 Coffman, 1962. June 6. Near Lakeport. * * * About 2 miles r e s t of Lakeport, 1973, Scot t Creek rose 1 1/2 f ee t and flowed s t e ad i l y f o r 11 days a f t e r

@ p. 180 and 181. being nearly dly before t he shock. Several wells i n Scott Valley rose 7 t o 10 f ee t , and the water was milky white f o r 3 t o 5 days. Four-inch-high undulating movement of f i l l s o i l was observed. About

0 10 miles southwest o f Lakeport, a geyserl ike spout of water i n Clear Lake was reported by t he press.

311 C 1906 Lawson and o thers , On the s ide of Mount Konocti, several large loose boulders were 1908, caused t o r o l l down, but no landslides nor cracks were observed. p. 188.


TABLE 9 .Spee i f i e descriptions of ground failures in the north coast counties region

Location number i s assigned t o each reported ground-failure s i t e . Corresponding numbers are found on p l a t e 5. Figure number re fers t o f igure i n t h i s report showing damage described under "Quotation" column. Failure type i s indicated by the following symbols. Corresponding symbols are found on p l a t e 5.

... Hil l s ide landslides including ro ta t iona l slumps, . . . ... River s t r e t che s with extensively f i ssured flood

block glides, debr i s avalanches, and rockfa l l s lai ins; pa t t e rn indica tes s t re tches of r i ve r affected and not width of disturbed zone

@ Streambank landslides including ro ta t iona l slumps and s o i l f a l l s 0 Sand b a i l s

+ Lateral spread Absence of ground f a i l u r e noted

Ground set t lement Miscellaneous e f f ec t s

Ground cracks not c l e a r l y associated with land- +U-+Ar ro i r s showing extent of area affected. Symbol s l i de s , l a t e r a l spreads, set t lement or shows f a i l u r e type primary f a u l t mvements

Accuracy with which f a i l u r e s i t e s can be located is given as follows: A, a s i t e t h a t can be accurately relocated; 8, a s i t e t ha t can be re loca ted t o within a few kilometers and probably could be located more accurately with fu r t he r inves- t iga t ion; C, a s i t e where the information i s i n su f f i c i en t t o all019 prec ise location.

P la te numbers i n t he "Reference" c o l m r e f e r t o p l a t e s in the o r i g ina l source material .

Laca- Fig- Fa i l - Accu- Year of Reference Quotation t i on "re ure ra- earth- NO. NO. type cy quake


The road between Point Arena and Mendocino was cut off by numerous s l i d e s (report of t o u r i s t ) .



Lairson and o thers , 1908, p. 187 and 188, p l a t e 738.

Lawsan and o thers , 1908, p. 174.


La!uson and others, 1908, p. 174.

Bridgeport, Mendocino County.--An extensive landslide came dotm in to the cu l t i va t ed f i e l d s on t he f l a t , wave-cut t e r r ace ea s t of the road.

Mendocim, Mendocim Cowzty.-- * . * The day a f t e r the shock there were numerous cracks i n the gmund. * * * numerous s l i d e s on t he c l i f f s took place, some very large.

1898. April, 14. * * Mountain roads east of Mendocino were rendered impassable by landslides and f a l l e n t r e e s .

WiZZets, Mendocim County * r * Small cracks across some of the s t r e e t s were reported, but they are not nari v i s ib le . * * * The Calley i s an old lake bed with ground water within 3 t o 4 fee t of the surface i n April. (See p l a t e 738.)

(W. T. Fitch.1--There were several small cracks across the roads a few miles south o f Fort Bragg; and back in the h i l l s there were more and l a rge r ones.

There are a number of f i s su r e s i n the mud f l a t s i n and near the Noyo River and Puddin Creek. The boys say there are cracks i n the streams. There are cracks i n the l e s s s o l i d rocks along the ocean shore l i ne .

(Eri Higgins.)--My house faces west. The ea s t pa r t was moved 6 inches south, breaking water and sewer connections. The west end o f the house did not move. Goods on shelves were thrown from the north s ide , but not from the south s ide . A l l br ick buildings i n town went down except two, and these were damaged.

TABLES 6 9 165

TABLE 9 .Spec i f i c descriptions of ground failures in the north coast counties region-Continued

Loca- Fig- Fa i l - Accu- Year of Reference t i on "re "re ra- earth- No. No. type cy quake

Quotation

317 B 1906 Lawson and others, Cteone, Mendocino County. * * * A l l svay-braces on the wharf had 1908, t o be replaced, and the r a i l r oad t r a ck was buckled i n many places. x p. 172. The bridge across the lagoon sank 3 f e e t i n some places, and was + thrown out of l i ne l a t e r a l l y , a l l t h e p i l i n g supporting the bridge

being l i s t e d t o t he south.

B 1906 Lawson and others, Inglenook, Mendocin0 County . * * On the banks of a small lake 1908, in the sandhi l l s between t he town and t he ocean, some a lders and

0 p. 172. irillaws f e l l owing t o a slumping o f the banks.

C 1906 Lawson and others, In the bed o f the Ten-Mile River, 10 miles north of Fort Bragg, 1908, where leve l surfaces occurred before, there were noted a f t e r the

0 p. 174 and 175. earthquake funnel-shaped depressions resembling ex t inc t volcanoes i n miniature. These were only a few f ee t i n diameter.

C 1906 Lawson and others, Westport + * * Large cracks were made i n the ground, and a f t e r 1908, the heavy r a in s of t h i s winter (March, 1907), l a rge landslides p. 172. occurred.

C 1906 Lawson and others, Hardy r * * The ear th cracked, both upon the mountains and near 0 1908, the creek, where t he ea r t h was broken away from the banks.

p. 172.

C 1906 Lawson and others, Monroe, Mendocino County . r Fissures opened i n the mountain 1908, s ides , and during t he present winter (March, 1907) many large land- p. 172. s l i d e s have r e su l t ed from these openings. [Located 7 m i . northeast

of Rockport according t o Board a f Geographic Names, Washington D.C.]

C 1906 Lawson and others, On the ea s t bank o f the main Eel River, t o the ea s t of Laytonville 1908, (A. S . Eakle), the ground was cracked fo r a distance of 300 yards, p. 170. the t rend of t he crack falloriing the course o f the r i ve r . The

crack was merely loca l in the a l l uv i a l bank of the stream, perhaps 100 yards from the water. A long bridge crossing the stream a t t h i s place showed no e f f ec t s o f the shock * * * .

B 1906 Lairson and others, Ju s t nor th of W. Geforth's house i s a crack 1,000 fee t long, 1908, trending N. 55' E . , and following roughly a low ridge running out p. 171 and 172. from the main h i l l s . I t cu ts almost a t r i g h t angles t o t he main

h i l l s and is i n s o f t material which has l i t t l e s l o w . I t could hardly be an ordinary s l i de . On t he t ap o f t he r idge [Poonkinney ridge?], where t he s o f t s t reak

crosses t he h i l l s a t an elevation of about 1,000 f ee t above the r i ve r , is a crack about SO f ee t long j u s t below a 1059 sandstone knob. trendine northwest o a r t l v across the draw a t a considerable a w l ; with t he c r e s t of t he h i i l s . I t i s i r r egu l a r and shows no diiplacement of any kind. I t could hardly be .i s l i de . S t i l l f a r t he r north, j u s t beyond E. Gevire's house [not p lo t ted on

ma01 and about 5 miles from Rabbins. i s another crack trendine . - northeast . It i s probably a s l i de . ' Mr. Gevirc s t a t ed t h a t &ere were several s l i d e s i n the h i l l s on a l l s ides of h i s house, but no o the r cracks were reported t o the north. To the south the cracks extended t o the r i v e r , but none were known south of the r i ve r . About a mile f a r t he r west, a t Poon Kenney, severa l more shor t

cracks were reported trending nor ther ly but varying i n d i rec t ion , and not connecting along t h e i r t rend , but I could not f ind any of these. About 6 miles north of the bridge on the Eel River, a t a sheep camp ca l l ed Hole-in-the-Ground [not p lo t t ed on the map], there are s a id t o be a great many cracks running i n various d i rec- t ions , but I did not v i s i t them. On the whole, I believe t h a t these cracks were a l l due t o the earthquake, but t h a t they are nothing mare than surface cracks due t o the ja r . They occur only i n the so f t s t r i p s of weathered sandstone and where they seem t o be r e l a t ed i n trend they a l so seem t o follow the s t r i k e o f the racks.


TABLE 9,Specif ic descriptions of ground failures in the north coast counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference t i a n "re "re ra- earth- No. No. type cy quake

325 C 1906 Lawson and o thers , One mile f a r t he r west toward t he Eel River, a crack cros t t he road toward the north. There i s a s t r i p o f s o f t sandstones and shales thru here resembling tha t found a t the Horse Ranch [loc. 3301 and s t r i k i n e t o the northwest. In t h i s s t r i o numerous cracks were found. of ten trending northwest but varying considerably. Four of these cracks were v i s i b l e , but o thers could not be found as the r a in s had healed them. I t was s a id t h a t t he do!mhill o r southwest s ide was sometimes higher than the nor theas t s ide. Only one of these cracks could be ascribed t o a s l i de . The o ther three might very well have been due t o t he shock.

326 C 1906 Lawson and o thers , Several cracks were reported crossing the road from Cavelo t o 1908, Laytonville near the t ap of the h i l l t o the north of Middle Eel p. 171. River. They are s a i d t o continue a t i r r egu l a r i n t e rva l s f o r a mile

o r more t o the north o r s l i g h t l y nar th of west. They genera l ly ' t rend north t o nor thrcs t , but vary considerably.

327 C 1906 Lawson and others, There were a great many ear th cracks farmed i n the Round Valley 1908, region. Some were examined, but many had been obscured by the p. 170. winter ra ins , while o thers were not v i s i t ed on account of the heavy

r a i n which s e t i n and made it impossible t o cross the streams or get about i n t he h i l l s .

328 C 1906 Lawsan and o thers , No cracks !rere found between Dobbins and Covelo. 1908, p. 171.

B 1906 Lawson and o thers , The extension [of loc. 3301 should pass f a i r l y close t a the road 1908, from Covelo, but none o f the ranchers along the road knew of any p. 171. cracks i n the h i l l s u n t i l Dobbins' p lace was reached, 10 miles

southwest, on sec t ion 14, township 23 N . , range 13 W. Here a crack 600 fee t long, t rending N . 25' W., occurs an a bench 150 f ee t wide, made up of s o f t alluvium gravel , e t c . , bounded on the northeast by a s teep h i l l of serpentine; i n t he southwest by a s teep slope t o the creek 200 f e e t below, and on t he northwest and southeast by bedrock ridges. The crack occurs near the outer edge of the bench and the creek (southwest) s i de is a few inches higher than the h i l l s ide. I t does not continue i n t o the hard rocks a t e i t h e r end. Between the creek and the h i l l the g m m d i s s o f t , miry, and f u l l of springs, while a t t h e edge of the h i l l i r r egu l a r cracks are same- times seen, showing t ha t t he muddy f l a t had likewise s e t t l e d r e l a t i v e t o the h i l l and indica t ing t h a t t he s o f t cent ra l area had s e t t l e d r e l a t i v e t o the hard, dry slope toward t he creek and t he bedrock of t he h i l l . The crack runs under the cabin where there was t h e grea tes t movement, but tho t he cabin i s on four pegs, it was not disturbed.

330 A 1906 Lawson and others, About 20 miles north of Covela, about s ec t i on 2, townsl~ip 24 N. 1908, range 14 W . , on the Horse Ranch, and about 700 f ee t above the north p. 170 and 171. fork o f the Eel River, i s a crack about 40 f e e t acmss and 600 f e e t

long. A t t h e southeast end a r idge of massive sandstone makes t ha t pa r t o f the t e r r ace somewhat wider. A t e i t h e r end are small gu l l i e s . At the back, t o t he nor theas t , a r a t he r steep h i l l of sandstone r i s e s abruptly from the te r race . Below, t o the southwest, t h e t e r r ace ends i n a s teep slope which shows evidence of repeated s l i d ing and has several springs near i t s base. There are no t r e e s on t h i s slope, but t he h i l l back of t he t e r r ace i s covered with t r e e s and there are some t r e e s on the t e r r ace , mostly on t he h i l l s i de of t he crack, a l t ho several oaks 8 inches i n diameter are on t he s i de toward the r iver . The main crack is about 400 f ee t long. I t is i nd i s t i nc t and discon- nected a t t he northwest end, but gradually becomes more prominent till it reaches a point j u s t beyond t he center where t he r i ve r , o r sourh- west s ide , i s 6 inches higher than the h i l l s i de , and there i s an open gap of about 8 inches. I t then begins t o d ie out and upon reaching

TABLES 6 9 167

TABLE 9 .Spec i f i c descriptions of ground failures in the north coast counties region-Continued

Loca- Fig- Fa i l - Accu- Year o f Reference t i o n ure ure ra- ea r th - No. No. type cy quake

Quotat ion

1906 C a l i f o r n i a Department o f Water Resources, 1971, p. 41.

1906 Lawson and o t h e r s , 1908, p. 387.

1906 Lawson and o t h e r s , 1908, p. 58.

1906 Lawson and o t h e r s , 1908, P. 56, f i g . 10.

1906 Weekly Hwnboldt rimes, 1906a.

1961 Coffman, 1973, p. 180.

t h e sandstone r i d g e t u r n s about t h e edge o f t h e r i d g e and con t inues about 100 f e e t more i n t h e shape of i r r e g u l a r cracks along t h e r idge . * r r The h i l l s f a r a cons ide rab le d i s t a n c c on a l l s i d e s o f t h i s crack are covered wi th o l d s l i d e s .

An unpubl ished r e p o r t i n t h e f i l e s o f t h e Northwestern P a c i f i c Ra i l road r e f e r s t o a l a r g e s l i d e on t h e Eel River near I s l a n d Mountain which blocked i t s flow i n Apr i l 1906. The s l i d e rias a t t r i - bu ted t o t h e San Francisco ear thquake, bu t t h e exac t d a t e o f t h e s l i d i n g i n A p r i l i s unknown. According t o an a r t i c l e i n a Eureka newspaper, t h e Humboldt Standard of Apr i l 26, 1906, t h e ear thquake was d i s t i n c t l y f e l t i n t h e Alderpoint-Fort Seward area and reportedly "stopped t h e water i n t h e r ive r" . Th i s may be i n r e f e r e n c e t o a temporary blockage upstream, perhaps t h e s l i d e a t I s l a n d hlountain r e f e r r e d t o i n t h e r a i l r o a d r e p o r t .

The most no tab le o f t h e ear th-avalanches occurred where t h e sea- c l i f f s are lhighest and s t e e p e s t . Th i s happens an t h e c o a s t of Humboldt County, between Cape Mendocino and Po in t Delgada. Not only are t h e c l i f f s h e r e p a r t i c u l a r l y f avorab le f o r l a r g e ea r th - avalanches, but t h e c o a s t h e r e i s c l o s e t o t h e l i n e o f t h e f a u l t which caused t h e ear thquake, and s o rece ived an e x c e p t i o n a l l y severe shaking. For many mi les o f c o a s t t h e r e was a genera l s l i p p i n g of rock and e a r t h i n t o t h e sea, doim very p r e c i p i t o u s s e a - c l i f f s ranging up t o over 2,000 f e e t i n he igh t . Between S h e l t e r Cove and Po in t Arena, t h e s e a - c l i f f s are n o t so high nor so cont inuous, but t h e r e was n e v e r t h e l e s s a very g e n e r a l , and l o c a l l y l a r g e , shedding of m a t e r i a l from t h e i r f a c e ; and t h e sea was muddy f o r many days a f t e r t h e ear thquake i n consequence o f t h e d e j e c t i o n b f t h e d6br i s upon t h e shore , wi th in range o f t h e a t t a c k o f t h e waves.

On t h e south s i d e o f t h e cove [She l t e r Cove] t h e r e are t h r e e p a r a l l e l deep gorges which extend a s h o r t d i s t a n c e i n t o t h e h i l l s ; and t h e i r con t inua t ion over t h e h i l l s is shown by s l i g h t depress ions which appear t o have been c l e f t s which have become almost f i l l e d with t h e wash o f t h e h i l l s . Along a l l t h e s e l i n e s o f weakness f i s s u r e s were opened and t h e ground subsided 2 t o 3 f e e t . Cross f i s s u r e s running from one depress ion t o ano the r are a l s o p resen t . The t r e n d o f t h e main f i s s u r e s [ f a u l t ? ] fol lowed t h e coas t , which i s northwest-south- e a s t . On t h e h i g h c r e s t s o f t h e Cooskie and King Mountains, [see loc . 3321 which border t h e c o a s t n o r t h o f t h e town, f i s s u r e s and l a n d s l i d e s were r e p o r t e d by ranchers looking f o r c a t t l e , but t h i s r eg ion was n o t v i s i t e d . In t h e range sou th of t h e cove l a n d s l i d e s were a l s o r e p o r t e d and a photograph o f a l a r g e one was taken.

[See f i g . 10 a t end of t a b l e s . ]

At S h e l t e r Cove + + * r h e severe shock a t 5 o ' c lock , wi th t h e he lp o f t h e ocean waves, washed about twenty acres o f land near t h e wharf i n t o t h e sea, l eav ing a deep depression. The wharf road from t h e t o p a f t h e b l u f f t o t h e warehouse i s completely des t royed by a huge s l i d e , making i t impossible t o reach t h e wharf even an f o o t . * * * a chasm aver a foo t wide was made w i t h i n a few f e e t o f t h e h o t e l . The roads are blocked wi th f a l l e n t r e e s e v e r w h e r e ou t t h i s !ray.

1961. April 5. Off c o a s t of nor the rn C a l i f o r n i a . F e l t p r i n c i p a l l y i n Humboldt County. At t h e Bear Harbor Ranch, about 10 mi les sou th of E t t e r sburg , a 50-yard s l i d e occurred. Magnitude 5.0.


TABLE 9.Specif ic descriptions of ground failures in the north coast counties region-Continued

Loca- Fig- Fail- Accu- Year of Reference t ion u r e "re ra- earth- No. No. type cy quake

Quotation

336 C 1906 WeekZy HmboZdt Times, 1906a.

337 B 1906 Lawson and o thers , 1908, p. 58.

338 B 1906 Lawson and others, 1908, p. 169.

B 1906 The Ferndale X Enterprise,

1956.

Briceland was more badly shaken up than t h i s place [Garberville]. J. W. Bowden's s t o r e and Ben Harris ' ho te l were both moved from t h e i r foundations, and t he s t o r e was badly twis ted and shaken on one side. A f i s su r e some inches wide runs the length of one of the s t r e e t s .

Miranda. The r i v e r became very muddy and the ground was cracked i n places as much as two f ee t across and f o r severa l hundred yards in length.

South f ~ a m Hadley's ranch a t Big Flat , the precipitous mountain slopes have been destroyed by extensive and high landslides, the dislocated materials o f which have frequently advanced out upon the beach in the form o f g lac ie r - l ike tongues. The waves a t high t i d e have s ince n i p t these protruding masses and truncated them a t t h e i r ends. Many of the s l i d e s occurred apparently on the s i t e s of o lder ones. Their cont inui ty and extent made the discovery of the f a u l t i n t h i s neighborhood impracticable. The prevalence of great s l i d e s along the coast , back inland, seems t o suggest the pos s ib i l i t y of t he f a u l t curving along the coast * .

Petrolin, HwnboZdt County. * . * Cracking of the land occurred along the edge of the r i v e r i n close proximity t o the ho t e l * r

A note from M r . Blackbum regarding t h i s same town says t ha t the only place which is reporred f o ha"; su f f e r i d r e l a t i ve ly more than Ferndale i s the l i t t l e town of Pe t ro l ia , on the Mattole River; * * * the ear th cracked very much and made wide f i s su r e s ; many s l i d e s occurred and the shock was heavier.

Pe t ro l i a Badly H i t . The ground from the North Forks t o the edge o f town i s furrowed, j u s t as though it had been plowed. On t he r i v e r bar near town the ground opened and water shot high

in the a i r . One end of the amroach t o the North Fork bridge has . . s e t t l e d one foot . The s t e e l bridge across Cook's gulch [near Upper Mattale] s e t t l e d

a t one end a foot and a ha l f . Bath bridges are passable.

A t Pe t ro l ia . * * * Cracks i n the ea r t h are noticeable i n many places. * * * The bridge near Levant Cook's place sunk a t one end about 18 o r 20 inches. Acmss the r i v e r from Pet ro l ia a huge s l i d e occurred, the mountain s i de pa r t l y going i n t o t he water and throwing a dam ha l f way across the stream.

C 1923 IVood, Allen, 1923 January 22. I X . Upper Mattole and Pe t ro l ia , where most of and Heck, the chimneys f e l l and there were many aftershocks. Bad s l i d e s on 19 39, nearby roads. p. 19.

C 1906 WeekZy HwnboZdt Upper Mattole. * * + The waters of the Mattole r i v e r were splashed Times, two o r three rods each s ide of the natural channel along the valley. 1906a. The roads are cracked and contain many p i l e s of rubbish and gravel.

Thousands of tans of d i r t and rocks have s l i d over precipices.

1968. June 25. Petrolia-Honeydew area. * * , A t Pe t ro l ia , minor landslides were noted and t he press reported la rge ground cracks along t he Mattole River.

339 67A 0 A 1906 Lawsan and others, Cape Fortirnas [ ~ a l s e cape] earth-slump (F. E. Matthe*).--This 67B 1908, lands l ide , immediately south o f Cape Fortunas, i s by f a r the mast

p. 390 and 391, extensive one on t he northern coast . (See p l a t e 127A, B.) In May, p l a t e 127A, 1906, it projected i n t o t he ocean f o r about 0.25 mile, l i k e a p l a t e 1278. hummocky headland of i r r egu l a r out l ine ; indeed, it formed a new

cape on the coast- l ine, but w i l l doubtless rap id ly be cut back by

TABLES 5-9

TABLE 9 .Spec iFc descriptions of ground failures in the north coast counties region-Continued

Loca- Fig- Fa i l - Accu- Year of Reference Quotation t ion "re "re ra- earth- NO. No. t w e cy quake

t he ac t ion o f the waves. I t s length, i n the d i rec t ion of i t s movement toward the ocean, i s estimated a t l i t t l e short of a mile; i t s width var ies from 0.25 mile t o 0.5 mile. I t s t o t a l descent, from the summit of the higher scalps a t i t s head t o the leve l of the sea, i s probably l e s s than 500 f ee t . I t s sur face i s encoodingly i r regu- l a r , with many large humps and hollowr. Over large areas the sod i s more o r l e s s rhythmically broken by deep cracks extending a t r i gh t angles t o the d i rec t ion of movement. These cracks are only a few fee t apar t , and the sad-blocks between them l i e mostly i n t i l t e d a t t i t udes , making t he area exceedingly d i f f i c u l t t o traverse. The general aspect i s not unlike t ha t of a much crevassed g lac ier . In some places, however, t he mass seems t o have been t o m apar t so completely t ha t the sod i s not merely broken but almost swallowed up o r buried, the bmwns and yellows o f the under s o i l being the preva i l ing t i n t s . Around its head are a number of steep scarps, from 100 t o 200 f ee t high. They are espec ia l ly prominent on the north s i de , and again toward t he southeast ; but over considerable s t r e t che s between these two s e t s , t he broken surface of the s l i d e joins the unbroken h i l l s i d e s t o the ea s t without s i gn i f i c an t o f f s e t . Owing t o t h i s , t h e s l i d e i s e a s i l y approached from the ragon road (from Centerv i l le t o Cape Town), which passes close by its head. The longitudinal p r o f i l e of t he landslide is one of gentle slopes for the mast p a r t ; its dec l iv i ty is not a t a l l g rea t , and i n a few places even reversed slopes occur. I t s noteworthy fearure i s not i t s ve r t i c a l drop but its great forward movement. In a sense it has flowed l i k e a p a r t i a l l y p l a s t i c mars, expanding and advancing 0.25 mile beyond the coast- l ine. but descendinn only a feu hundred . ~

f e e t . In i t s general aspect , as well as i n the nature of i t s movement,

the Cam Fortunes landslide is altowether d i f f e r en t from those ~~~ ~ - - ~ - ~

observed f a r t he r south, pa r t i cu l a r l y along t he mountainous coast both north and south of Point Delgada, which, i n e f f ec t , did l i t t l e e l s e than revive a s e r i e s o f old lands l ide facets . This may not be apparent t o an observer on the beach, but i s qu i t e s t r i k i n g when t he coast i s viewed i n i t s en t i r e t v from a vessel off-shore. These - ~ - ~ -

face ts ex is ted before t h i s earthquake, and had been recognized as such. They are conspicuously out l ined against the dark timbered slopes behind them, r i s i n g from 1,000 t o 2,000 f ee t above t he shore, and affording an important s e r i e s of landmarks fo r the mariner. In strong cont ras t with these bold mountain forms i s the region i n lihich the Cape Fortunas landslide took place. The land here can scarcely be ca l led mountainous; and while it breaks o f f i n c l i f f s a t the coast and i s t raversed by many f a i r l y deep d r a w , i t is e s sen t i a l l y a region of subdued r e l i e f . Great dec l i v i t i e s are notably absent, except i n the s ea - c l i f f s , and even these are only a few hundred f ee t high. A t t h e same time, evidences of former landslides may be seen on every hand. They are not extensive, as a ru l e , and arc as l i k e l y t o occur on gentle slopes as on steep ones. In a few cases only is a marked do3unslip noticeable, r e su l t - ing in the uncovering of a stecp scarp; i n nearly every instance the d is loca ted mass appears not so much t o have sheared off and dropt from i t s former pos i t ion , as t o have expanded o r slumped, with an accompanying subsidence of i t s surface. The billowy and irregu- l a r l y p i t t e d appearance of these areas, together ivith the rank vege- t a t i o n t ha t covers them, afford the pr inc ipa l marks of ident i f ica t ion . Both from t h e i r cha r ac t e r i s t i c form, sugnestive o f p l a s t i c flow, and . .. from t h e i r mode of occurrence, it seems reasonable t o i n f e r t ha t ground-water plays an important =^ole i n t h e i r genesis. They are apparently masses which have changed t h e i r shape i n obedience t o a lessenine of cohesion i n t h e i r i n t e r i o r . through sa tura t ion with " - water. Whether the movement be i n i t i a t e d by an earth-tremor o r nor, i t i s i n every case e s sen t i a l l y an adjustment t o a more s t ab l e posi- t ion , rendered necessary by a change i n t he physical cons t i tu t ion of the mass.

I t is t o t h i s category of landslides t ha t tho one a t Cape Fortunas belongs. While there are scarps i n various places a t i t s upper end, these are r e a l l y ins igni f icant fea tures alongside of the extensive


TABLE 9.Speeif ie descriptions of ground failures in the north coast counties region-Continued

Laca- Pig- Fa i l - Accu- Year of Reference Quotation t ion ure ure ra- earth- No. No. type cy quake

t r a c t of t he s l i d e i t s e l f . lYhat downslipping occurred on these scarps was merely an incident i n the e n t i r e movement. Both i n the large r a t i o between i t s horizontal advance and its ve r t i c a l drop, and i n i t s general appearance, the Cape Fortunas lands l ide i s closely ar~alogous t o tile )numerous l e s s e r s l i d e s referred t o ; and there is good reason f o r the be l ie f t ha t , l i k e them, i t consisted e s sen t i a l l y of an adjustment of equ i l i b r i a " i n a p a r t i a l l y water-saturated mass. I t probably had long been i m i n e n t before the earthquake s t a r t e d it.

A 1906 Lawsan and others, Near t h e False Cape it threw the old h i l l , on which t he O i l Creek 1908. coast road ran. out i n t o t he ocean for 0.5 mile. It i s estimated

t h a t 200 acres were thrown in to t he ocean. Qui te a number of c a t t l e went with the h i l l . The s l i d e i s s a id t o have obscured the view of Cape Mendocin0 l i g h t from Trinidad heads.

A 1906 Jordan, 11. Landslips, etc. In the meisoseismal area, there were a grea t 1907, many cases of mountain s l i de s . The most remarkable among these was

0 p. 296 and 299. t ha t which occurred near Cape Fortuna (False Cape), where an enornous quanti ty of debris was detached fmm a munta in s ide and was pushed i n t o the ocean, c rea t ing a new promontory of about 314 mile length. [The name Cape Fortunas was o f f i c i a l l y changed t o False Cape on Oec. 14, 1939, Board on Geographic Names, Washington O.C.]

A 1906 TheFerndote A t the Woodland Echo da i ry ranch, j u s t t h i s s i de of O i l creek on Enterprise, the Centerv i l le beach, a la rge mountain s l i d i n to t he ocean and now 1956. extends i n to the water for a distance of probably a h a l f mile, com-

p l e t e ly obstructing t he view o f the Cape Mendocino and Table Bluff l i gh t s , which before t he upheaval were p l a in ly v i s i b l e t o each s t a t i on . On t h i s mountain a t t he time o f the quake were four o r f i ve head o f c a t t l e , and they are reported t o have been wiped out of existence. The road leading from the Woodland Echo rancli t o Ferndale has been completely obl i te ra ted near t he s l i de .

1906 The Ferndaze Enterprise, 1956.

1906 The HwnboZdt Times, 1906.

1954 The HwnboZdt Times, 1954b.

1906 Fle/eekZv H d o Z d t Times, 1 9 0 6 ~ .


At the rear of A. Boyd's residence a t Port Kenyon a large f i e l d bordering S a l t r i v e r was spread open i n many p lacer , several acres of the land s e t t l i n g a couple of f e e t . From its appearance it would seem tha t water spurted i n la rge quan t i t i e s from the ground. On the north bank of S a l t r i v e r a t the latrer bridge the land has s l i d i n and cracked f o r a d is tance o f severa l hundred fee t and t o a width of t h i r t y o r f o r t y fee t . The bridge i t s e l f does not seem t o have been damaged any and i s presumably i n as good condition f o r t r a v e l as before t he shack. A l l along Sa l t r i ve r , on e i t h e r s ide , but more espec ia l ly on the south s ide , f i s su r e s can be noticed, and i n some instances of severa l f e e t i n width, and we are t o l d by those who have t r i e d probing t he gaps t h a t they appear t o be p r ac t i c a l l y bottomless.

A t Fort Kenyon a vegetable garden turned i n to a lake, the water being a depth of about two fee t .

[Ferndale] S t ruc tu r a l damage was reported a t Rings Pharmacy, where t he building s e t t l ed . t * across t he s t r e e t a s im i l a r s t r uc tu r a l damage occurred t o t he Martin and Betriga fountain.

On the Wildcat road, one and a ha l f miles from Ferndale, the road was f i l l e d i n by a b ig s l i de , but w i l l be opened f o r t r ave l today.

At Dungan's Ferry, on the north bank of the Eel River, t h e ground was f u l l of f i s su r e s . Every bar on the r i v e r had been opened by f i s su r e s , and the gravel toppled over leaving b ig ditches, some 6 fee t deep and over 500 f e e t long. Coming up on the mainland t he mad had dropt about 2 f e e t i n one p lace and was f u l l o f small

TABLES 6 9 171

TABLE 9.Speeif ie descriptions of ground failures in the north coast counties region-Continued

Laca- Fig- Fail- Accu- Year of Reference Quotation t i a n ure "re ra- earth- No. No. type cy quake

f i ssures . A 40-acre f i e l d was en t i r e l y ruined. I t was heavily * f i ssured , having dropt down i n s t r i p s from 2 t o 6 f e e t wide, from 4 t o 6 f e e t deep, and from 5 t o 500 f e e t long, the f i s su r e s pointing

0 between' south and southwest. A l l the f i e l d s were f u l l o f quicksand volcanoes, some 1 t o 3 cubic yards i n s i z e . They were perfect

... miniature volcanoes, every one having a c r a t e r . I t i s s a id they

... ... extended 30 miles up the r i ve r .

C 1906 Lawson and others, On the f lood p la in of the Eel River t o the north of Ferndale, 1908, Professor Eakle repor t s t ha t t he ground was cracked for a distance p. 168, of 0.25 mile on the west bank of t he r i ve r . The cracks were in p l a t e 138A, close v i c in i t y t o t he r i v e r , and seemed t o be on t he l i n e o f an p l a t e 1388. old channel. A s e r i e s of pa r a l l e l cracks, some having a ve r t i c a l

Y displacement o f 2 fee t , t h e surface being upl i f ted and deprest , followed t he trend of t he r i v e r and were evidently loca l in t he

0 so f t alluvium. A t t h e time of the earthquake water and sand spouted up in several places t h r u openings which were in some cases 4 inches wide. Mr. Blackburn repor ts t h a t t h i s water remained on the sur face of the f i e l d s f o r some time a f t e r t he earthquake. In t h i s same connection, Mr. J. A. Shaw repor ts t ha t "a f i e l d on a + high bar near the Eel River was l i t e r a l l y shaken t o pieces, and water f i l l e d with quicksand was ejected several f e e t high. The r en t s run from north and south i n a curve t o e a s t and west. Some pa r t s are ac tua l ly cut i n to squares. The jump v e r t i c a l l y w i l l reach 2.5 f e e t . There were no such la rge r en t s t h ru t he valley generally, as the upper s o i l r e s t s an a clay foundation which seemed t o stand it a l l r igh t . , '

343 C 1906 WeekZy Hmbotdt The Scot ia [ ra i l road] l i n e went out of comiss ion by reason o f a Times, s l i d e a t t he b luf fs and t he breaking of two of t he heavy l a t e r a l 1906b. rods on the Van Duzen Bridge.

344 C 1906 The Ferndate Cock Robin Island cams i n f o r i t s share of t he shake, chimneys Enterprise, being torn down and many holes and cracks i n the ground made. The 1956. same destruction v i s i t ed Cannibal Island, it being s a id t h a t the

land t he r e t ha t was qu i t e high before the shake-up i s now lowered from one t o ten f ee t , while low places have been f i l l e d up. In

0 many instances where the ground opened a kind o f black sand or sediment oozed for th , showing t h a t i t must have been tlirown from the very bowels of t he earth. On the Hamner ranch on the Island, under lease t o Rasmus Nielsen, we are t o l d tha t t h i s sand o r sediment was very warm and t h a t snake arose from it f o r severa l hours a f t e r the convulsion.

C 1906 The H d o Z d t On Cannibal i s land the ear th trembled and cracked but the repor t 0 Times, t h a t mud and water issued fmm the f i s su r e s and rose i n t he a i r

1906. 100 f e e t could not be ver i f ied .

1932. June 6 . Hwnbotdt C o m t y . r * * a t Eureka Slough [loc. 3491, a r a i l r oad drawbridge was put out of commission; a t Loleta. small cracks appeared i n the gmund and a brick wall f e l l . Cracks 28 inches wide and severa l hundred f e e t long were observed on Cock Robin Island [ loc. 3441.

346 B 1906 Lawsan and others, South of E w e h ( H . H. Buhne).--A few days a f t e r the quake every- 1908, thing laokt a l l r i g h t along the road, excepting chimneys, u n t i l I p. 166. reached Fie ld ' s Landing, a t South Bay. Here the shock opened a

f i s su r e over 100 fee t long in t he middle of the road, which 6 teams

r( spent one day in f i l l i n g . Pelican Island, as it i s conmanly ca l led , opposite Field 's Landing, dropt 3 f e e t a t the pa in t where the United S t a t e s p i l e beacon stands. I t l e f t the beacon landing a t an angle of 45' from the southwest.


TABLE 9,Specific descriptions of ground failures in the north eoost counties region-Continued

Loca- Fig- Fa i l - Aceu- Year of Reference t ion ure ure ra- earth- No. No. type cy quake

Quotation

1906 The X d o t d t Times, 1906.

A t F ie ld ' s Landing around t he home of John Johnson, small cracks i n the ear th became geysers throwing out warm water f o r severa l hours, the flow f i na l l y abating about noontime. In front o f t h e hote l an the county road many cracks were i n evidence but they f i na l l y closed up. A l i t t l e beyond the Landing i n the county road was a crack about 18 inches wide and twelve t o fourteen f e e t long. A nine-foot s t i c k f a i l e d t o touch bottom and teams were busy a l l day t o f i l l up the gulch.

1906 The HwnboZdt Many are the repor ts o f sinking i n various sec t ions but out the Times, Elk r i v e r way it heaved up, breaking the water mains of the Eureka 1906. Water Company running thmugh t he Feckelstein place and t he Russ

claim.

1908 Coffman, 1908. August 18. Eureka. * + * A t Freshwater, a few miles north 1973, of Eureka, walls cracked, chimneys f e l l , and s o f t ground fissured. p. 162 and 163.

1908 Townley and Allen, 1908 August 18. * * * VIII. Humboldt Bay. * r * Reports from the 19 39, Seazy ranch, near Freshwater, s i x miles north of Eureka, s t a t e t h a t p. 150. the earthquake caused a b ig f i s s u r e i n the ea r t h f o r about one-half

mile.

1906 Weekly H d o Z d t Damage a t Sweasey Ranch. * * qu i t e a good deal of water pipe Times, across t he slough had been bmken, and i n many places the road was 1906. cracked.

1853 Holden, 1898, p. 41.

1865 Townley and Allen, 19 39, p. 45 and 46.

1906 Weekly HmboZdt Times, 1906b.

1906 WeekZy Hmboldt Times, 1906b.

1954 Coffman, 1973, p. 176.

1853. October 23; VIII. Three heavy shocks a t Humboldt Bay, Gal.--J. B. T. A t Eureka t t * the wharf sank 4 fee t .

1865. October I . 7 a.m. IX. Eureka. Heavy Shock. * * r "Fort Humboldt, a few miles below Eureka on t he Bay, rras even more roughly handled; a l l f o r t buildings were in jured and there was a f i s su r e along t he edge of the parade ground." [Also i n Coffman, 1973, p. 157.1

GREAT GAPS IN THE EARTH. A t the home of R. L . Haughey, the shingle manufacturer, was a scone

of havoc a f t e r t he earthquake had passed. A recent addit ion t o the residence was t o rn loose and moved a foot t o the southward, and a t t he same time sank about four inches. Another pa r t o f the dwelling a l so shrunk away from the main s t r uc tu r e and took a l i t t l e drop. Cracks were i n evidence i n the ear th a l l around t he property when

the gentlemen got out of the house, and water was spouting up through them. The cracks were about ten inches wide. but durine the day " they closed up, and l a s t evening were only about four inches across. AT THE EUREKA FOUNDRY. * * * the ground surrounding the p lan t was

cracked by the tremor o f yesterday morning. The ground sank mate- r i a l l y a l so i n places.

The large water mains of t he Eureka Water Company are badly twisted * * * .

1054. December 21 and 30. Eureka-Arcata areas. * * * In the poorly consolidated ground areas nor th and e a s t of Eureka t he r e were some p ipe l ine f a i l u r e s , and Eureka's main water reservoi r was cracked. A large sec t ion o f the older, downtown f i l l e d area of Eureka s e t t l e d from 2 t o 6 inches.

[Picture caption] * * the b ig shaker l e f t t h i s giant-sized f rac ture in the c i t y ' s surface on Hairthollie s t r e e t near Broadway. The crack's depth was unrecorded, but i t measured up t o 12 inches wide.


The following figures are those referred to in the preceding tables:

Table 6, location 118 Table 6, location 179

100 200FEET

w 0 25 50 METERS

APPROX. SCALE

0 50 100 FEET

0 25 50ME

FIGURE 68.-Map of landslide caused by the earthquake east of San Pablo (Lawson and others, 1908, p. 392).

FIGURE 7.-Dam at Crystal Springs Lake showing cracks formed by the displacement (Taber, 1906, p. 310).

Table 6. location 179

FIGURE 69.Sect ion of landslide shown in fig. 68, along the line A-A' (Lawson and others, 1908, p. 392).

FIGURES CITED IN TABLES 175

Table 8, location 270 Table 8, location 271 Table 8, location 271

FIGURE 25.-Arrange- ment of ridges on tidal flat near Inverness. Map. (Lawson and others, 1908, p. 79).

FIGURE 27.-Diagrams with exaggeration of vertical scale, to illustrate deformation of Inverness piers by shifting of mud toward the shore. Bailey's pier above; Martinelli's below (Lawson and others, 1908, p. 791.

FIGURE 26.Sketch of Inverness piers. Full lines show positions of piers after earthquake; broken lines show positions before earthquake, Dotted line shows shoreward limit of the shifting of bottom (Lawson and others, 1908, p. 79).

Table 8, location 302 I

I I

FIGURE 14.-Profile of southwest side of South Fork of Gualala River, showing relation of fault to geomorphic features (Lawson and others, 1908, p. 62).


Table 8, location 303

FIGURE 13.-Map of valley of South Fork of Gualala River, showing relation of fault-trace t o geomorphic features (Lawson and others, 1908, p. 61).

FIGURES CITED IN TABLES

Table 9, location 333

FIGURE 10.-Map of country traversed by fault to north of Shelter Cove, Humboldt County (Lawson and others, 1908, p. 56).

Documents

Historic Ground Failures in Northern California …HISTORIC GROUND FAILURES IN NORTHERN CALIFORNIA TRIGGERED BY EARTHQUAKES By T. L. you^ and S. N. Hoos~ ABSTRACT A major source of