STATE OF CALIFORNIA-THE RESOURCES AGENCY

DEPARTMENT OF CONSERVATION

DIVISION OF MINES AND GEOLOGY llAY AREA REGIONAL OfFICE 380 CIVIC DRIVE, SUITE 100 PLEASANT HILL, CA 9~23· 1997 PHONE. (415) 6*5920

A TSS 599-5920

Mr. Steven A. Kupferman

GEORGE DEUKMEJIAN. Gow:mor

August 31, 1990

Riverside County Planning Department 4080 Lemon Street, 9th Floor Riverside, CA 92501

Dear Steve:

We are placing on open file the following report, reviewed and approved by the County of Riverside in compliance with the Alquist-Priolo Special Studies Zones Act:

Geologic/seismic report, 20 acre parcel in NE~ of NW~ sec. 7, T.3S., R.2E., Cabayon area, Riverside County, CA; by Clopine Geological Services; 6/14/89; with addendum of 8/10/90.

I note that the San Gorgonio Pass fault was found outside the Special Studies Zones. We plan to evaluate that fault for possible revision sometime in FY 1991-1992.

EWH:hrk

cc: A-P file

Sincerely,

EARL W. HART, CEG 935 Senior Geologist &

Program Manager

August 23, 1990

Clopine Geological Services 13093 Bur.ns Lane Redlands, CA 92373

Attention: Gordon Clopine

=tiVE=t.)ii)c COUni:'! i»LAnninG i>E?A=ti:mEni:

Subject: Alquist Priolo Special Studies Zone Plot Plan m-12-- ------ ---A.P .N.: 519-110-005,006 and 007 county Geologic Report No. 741 Cabazon area

Dear Mr. Clopine:

We have reviewed your report entitled "Geologic/Seismic Report for 2 O Acre ( +) Parcel in the northeast quarter of the northwest quarter, Section 7, Township 3 South, Range 3 East, S.B.B. and M., Cabazon Area, Riverside County, CA," dated ,June 14, 1989, and your response to County review dated August 10, 1990.

Your report determined that:

1. An active trace of the San Gorgonio Pass Fault zone is located on the site, therefore·a high potential for surface ground rupture exists alorig this fault trace. This fault is delineated on the Site•Map, Map No. 3 in your report.

2. A maximum probable earthquake of Richter magnitude 7.5 to 8.0 is expected to occur on the San Andreas fault, located approximately 1.5 miles horth of the site.

!

3. A Richter magnitude earthquake of 7.5 located two miles from the site would result in a maximum peak rock acceleration of 0.73 g at the site.

4. Landsliding is not considered a potential hazard on the site.

5. The hazard from seismically induced ground subsidence is considered very low.

6. No water tanks exist up-slope of the site at present.

7. Hazard from seiching is not present on the site.

8. The potential for lurching on the site is low.

4080 LEMON STREET, 9TH FLOOR RIVERSIDE, CALIFORNIA 92501 (714) 787-6181

79733 COUNTRY CLUB DRIVE, SUITE E BERMUDA DUNES, CALIFORNIA 92201

(619) 342-8277

Alquist Priolo Special Studies Zone Plot Plan 11972 County Geologic Report No. 741 Page 2

9. The potential for liquefaction is considered very low to nil at this site. The hazard from lateral spreading is considered very low on the site.

Your report recommended that:

1. A setback zone of 60 feet on each side of the active fault trace shall be established. Construction of structures for human occupancy is prohibited within this zone. This setback zone is delineated on the Site Map, Map #3 in your report.

2. Seismic information in your report shall be considered by the project structural engineer.

3 • The project soils concerning possible considerations.

engineer shall make minor ground subsidence

recommendations for foundation

4. If any water storage tanks are placed on or to the north of the site, the inundation path shall be calculated by the project engineer should the tanks fail.

5. The location of the exploratory trenches of this investigation shall be located by the project engineer, following their field survey, on a suitable large-scale map. The location of the fault trace and setback zone shall also be shown on this map.

6. The exploratory fault trenches shall be inspected for comp!tction and recommendations for recompaction shall be made by the project soils engineer.

7. Property owners and tenants of proposed improvements shall be made aware of the seismic risks involved with properties in close proximity to active faults.

8 . A Registered Geologist shall review project grading shall be on-site during grading to evaluate conditions exposed during grading.

plans and geologic

It is our opinion that the report was prepared in a competent manner consistent with the present "state-of-the-art'' and satisfies the requirements of the Alquist-Priolo Special Studies Zones Act, the associated Riverside County Ordinance No. 547. Final approval of this report is hereby given.

•..

Alquist Priolo Special Studies Zone Plot Plan 11972 County Geologic Report No. 741 Page 3

We recommend that the following conditions be satisfied LDC clearance and/or before issuance of any County associated with this project:

prior to permits

1. The Fault Setback Zone shown on Map #3 in the Clopine Geological Services report shall be delineated on the Plot Plan, Exhibit A, prior to LDC clearance.

2. The following notes shall be placed on the Plot Plan, Exhibit A prior to LDC clearance:

a. "This property is affected by earthquake faulting. Structures for human occupancy shall not be allowed in the Fault Setback Zone."

b. ''Riverside County Geologic Report No. 741 was prepared for this property by Clopine Geological Services on June 14, 1989 and is on file at the Riverside County Planning Department. The specific items of concern are surface fault rupture, strong ground shaking and uncompacted trench backfill."

3. The exploratory trenches were backfilled, but not compacted, and shall be addressed by the project geotechnical engineer if any structures are contemplated for construction over any portions of these trenches, prior to issuance of any County permits associated with this project.

The recommendations made in your repo.rt concerning seismic/geologic hazards shall be adhered to in the design and construction of this project. r Very truly yours,

SAK: jb cc: Ginsburg Craig Associates - Applicant

CDMG - Earl Hart Building & Safety - Norm Lostbom (2) Commercial/Industrial Team - John Ristow

•

CLOPINE GEOLOGICAL SERVICES

TITLE:

DATE:

GEOLOGICAL AND ENVIRONMENTAL REPORTS AND EVALUATIONS 13119.1 BURNS LANE

BF.DL/\NUS, CALIFORNIA

92.'173

GEOLOGIC/SEISMIC REPORT FOR 20 ACRE (±) PARCEL IN THE NORTHEAST QUARTER OF THE NORTHWEST QUARTER, SECTION 7, TOWNSHIP 3 SOUTH, RANGE 2 EAST, S.B.B. & H., CABAZON AREA, RIVERSIDE COUNTY, CALIFORNIA.

JUNE 14, 1989

PREPARED FOR: HR. STEVEN L. CRAIG CRAIG AND ASSOCIATES

PREPARED BY:

4120 BIRCH STREET, SUITE 110 NEWPORT BEACH, CALIFORNIA 92660

HR. GORDON CLOP!NE REGISTERED GEOLOGIST NO. 511 STATE OF CALIFORNIA

CERTIFIED PROFESSIONAL GEOLOGIST NO. 6125 AMERICAN INSTITUTE OF PROFESSIONAL GEOLOGISTS

• .• •

t:LOPINE GEOl.()(;)CAt. SERVICES GFAIL~l(;U:.11. A~D s.:/Oj~IAUIOlr.ll'TtL Rt.:l"UK"D Af'll J::~ALU~Tl()>j8

June 14, 1989

TABLE OF CONTENTS

GEOLOGIC/SEISMIC REPORT FOR 20 ACRE (*) PARCEL IN THE NORTHEAST QUARTER OF THE NORTHWEST QUARTER, SECTION 7, TOWNSHIP 3 SOUTH, RANGE 2 EAST, S.8.B. & H., CABAZON AREA, RIVERSIDE COUNTY, CA.

Topic Page Nuaber

I. INTRODUCTION Location, Improvements, Vegetation, Slopes 1 Elevations, Alquist-Priolo Zone, Access,

Authorization 2 Hap 1 Location of Subject Property, San Gorgonio Pass Fault, A.P. Soundaries 3

II. THE INVESTIGATION Regional Review and Seismic Setting Hap 2. Earthquake Epicenter Hap Seismic Considerations and Analysis Methods of Study

III. RESULTS OF STUDY - SITE GEOLOGY

4 6 7

11

Rock Types 13 Structural Geology 14 Groundwater, Drainage, Slope Stability 15 Surface Fault Rupture, Fault Hazard Ground Subsidence, Seismically Induced Flooding, Seiche, Lava Flow, Tsunami, Lurching, Liquefaction, Lateral Spreading 16

III. CONCLUSIONS 17

IV. RECOMMENDATIONS

V • REFERENCES

MAP 3.

HAP 4.

GEOLOGIC MAP AND TRENCH OF SUBJECT PROPERTY GEOLOGIC HAP, REGIONAL

TRENCH LOG FOR TRENCH lA

LOCATION 1: 2400 1:24000

TRENCH LOG FOR TRENCH 1B AND 1C TRENCH LOG FOR TRENCH 2 AND TRENCH 3 TRENCH LOG FOR TRENCH 4 AND TRENCH 5

HAP

18

19

24

25

26 27 28 29

APPENDIX A: Prominent Earthquakes in California 30 APPENDIX B: Modified Mercalli Intensity

Comparison with Richter Magnitude 31 APPENDIX C: Fault-Hazard Zones in CA. by Hart 32

Alquist-Priolo Special Studies Act 38

TELEPHONE !n41 794·6700

CLOPINE GEOLOGICAL SERVICES

GEOLOGICAL AND ENVIRONMENTAL HEPORTS AND EVALUATIONS 13093 BURNS LANE

Mr. Steven L. Craig Craig and Associates

June 14, 1989

4120 Birch Street, Suite 110 Newport Beach, California 91660

Dear Mr. Craig:

REGARDING: GEOLOGIC/SEISMIC REPORT FOR 20 NORTHEAST QUARTER OF THE NORTHWEST QUARTER, SOUTH, RANGE 2 EAST, S.B.B. & M., CABAZON CALIFORNIA.

REDLANDS, l:Al.IFOHN!A

92.173

ACRE (~) PARCEL IN THE SECTION 7, TOWNSHIP 3

AREA, RIVERSIDE COUNTY,

At your request, I have conducted investigation of the above described property.

a ·geologic/seismic

I. INTRODUCTION

The property described in this report is on the north side of Seminole Drive and lnterstate 10, approximately midway between Fields Road to the west and Millard Pass Road to the east. It is further described as Assessor's parcel 519-110-5, 519-110-6 and 519-110-7, as shown on Assessor's Map Book 519, Page 11, Riverside County, California. The property is shown on the Cabazon Quadrangle, U.S.G.S., 1956, photorevised 1972. See the maps of this report for further site location.

The property is basically un-improved at the present time. Native vegetation consists of scattered cat's claw shrubs (~cacia)

and one palo-verde (Cercidium). with various native and introduced grasses/weeds. The property has been the si~e of fairly extensive du111ping of surficial fill and unwanted junk, and the eastern por·tion is littered with old tires, wood and shelving, chairs, washing machines, a SO-gallon drum of sulfur (?), metal cans, etc .. Several abandoned structures and a camper-shell exist in the. southeast region of the. property, an in-use storage container is located at the south end of Parcel 6.

The northern portion of the property has low hills, with slopes of approximately 8 degrees, and the central and southern portion is oi more gentle slope of 2 or 3 degrees. Slopes are to the south, as a portion of the drainage of the San Gorgonio River. The San Gorgonio River active drainage, draining to the southeast, is adjacent to the property on the southwest side of Interstate 10. Three intermittent drainage channels cross the property, from north to south.

Page 1

CLOPINE GEOl,OGlCAL SERVICES tallllJM;H:AL. ~M~ L\O~lrttl!l:ll~~L ll!:rtll!TII "~D E~"LIJA11'li11'1~

Steven Craig June 14 19,,,,a.,_9,._ ____________ _,_P_,,a'-'g"'e"---'2"-

Elevations range from a high of 2069 feet in the northeast to a low of 2022'in the southeast. Field survey was conducted utilizing a 200-scale map with 4 foot contour interval prepared by the Riverside County Flood Control and Water Conservation District, revised 1971. Locations on the map were surveyed using the Brunton compass and measuring-wheel.

Trench locations were surveyed by Licensed Surveyor of Sanborn­Webb Inc., Palm Springs, CA. on June 2, 1989.

A portion of the southeastern corner of the subject parcel is included within an Alquist-Priolo Special Studies zone (See Hap 1 and Hap 3, this report). The remainder of the parcel is not included in a Special Studies zone, but it is shown in U.S.G.S. Open File Report 85-365 (Hatti, Horton, Cox, 1985), as the location of the San Gorgonio Pass fault, with the trace striking northwest­southeast.

Latitude of the approximate degrees, SS minutes, SO seconds North; 49 minutes, no seconds West.

center of the property is 33 and longitude is 116 degrees,

Access to the property was made from Seminole Drive in the southeastern area of the subject parcel.

Written authorization to conduct this study was given by Mr. Steven L. Craig on May 20, 1989.

Grading plans for the subject Sanborn Webb, Inc., Palm Springs. being prepared by John Byerly, Inc.,

property are being prepared A preliminary soils report

Bloomington.

by is

The work of this investigation was conducted in accordance with accepted methods and procedures related to the practice of geology in California. No other warranty is expressed or implied.

CLO'PlNE GEOLOGICAL SERVICES (,~IL!K<U:AL Mm J.:.'(\'lll'Ol'IMl:'.ff'l'AL Ki::l"(IKn Al'IU l::l"ALL'ATIOl'I~

Steven Craig June 14 1989 Page 3

G 0

--- i.. _______ ::-1,,-~---~.----- ''

Map l. Location of Subject Property, and Alquist-Priolo Special Studies Zone boundaries. San Gorgonio Pass fault as shown on State Map (1974) approximately located. This map a portion of the Cabazon Quadrangle, U.S.G.S., 1956, photorevised 1972, scale 1:24,000. North to top of page as indicated.

' __ .... ' ' i _,.

Cl,OPINE GEOLOGICAi., SERVICES Gl::OUl(;lt:AL Ai'jll K/j\lllU.~111[h'AL l'!t.)•unTI A~[) F;HLUATIOl!r.:I

Steven Craig June 14, 19$9 Page 4

II. THE INVESTIGATION

A. Regional Review and Seismic Setting

southern California in the vicinity of the subject property is affected by a number of significant fault zones, and all have regional importance to site geology. Faults of importance are the San Andreas fault (north branch) located approximately S miles north of the subject property; the Banning fault (south branch of the San Andreas) located approximately 1_5 miles north of the property; the San Jacinto fault, located approximately 10 miles from the property; the Whittier-Elsinore fault, located approximately 37 miles from the property; and the San Gorgonio Pass fault complex, located on the property itself.

Two major structural blocks are identified as in the southern California region in the vicinity of the subject property_ They are; (1) the Transverse Ranges, represented locally by the San Bernardino mountains, located north of the subject property north of the Banning Fault, and (2) the Peninsular Ranges, represented locally by the San Jacinto mountains, located south of the ... subject property. The San Gorgonio Pass, site of the subject property, thus is located at the boundary between these two major physiographic provinces of California.

Fault traces of the faults listed above have observable features and characteristics that indicate their approximate location, such as variations in surface topography, types of vegetation, distribution of vegetation, rock exposures, landform development, offset streams and other drainage patterns, and variations in ground water levels in a region. Detailed geological mapping and field study, often including exploratory trench excavations, are utilized to determine more detailed geological conditions at a particular site.

With the possible exception of the San Andreas fault, no fault mentioned above has caused surface disruption between Cajon Pass and San Gorgonio Pass in historic time (since 1769). The faults mentioned have caused surface disruption west of Cajon Pass and east of San Gorgonio Pass (1857, 1899, 1910, 1948, 1968, 1986 ?). Thus the site of the subject. property 1s at the. eastern end of a region now described as the "San Gorgonio - Cajon Knot" (Sykes and Seeber, 1985), and it is known to be an area where a "great earthquake" is considered likely in the future. Recurrence intervals for rupture along the San Gorgonio-Cajon knot of the San Andreas faulty system have been calculated (Sykes and Seeber, 1985) at about 30 to 500 years_

l:LOPINE GEOLOGICAL SERVICES 1a:m.1N;Jt:AI. Mfn ':~\'IR01'MUVT"l AEf'ORT!I ~l'D E~Ut;~TIOf'<?I.

Steven Craig June 11., 1989 Page 5

See Map 2 and Appendix A of this report for a listing of important regional seismic events for 1769-1974. Earthquake data since 1974 are described by Toppozada et. al. (1979) and Sherburne et. at. (1985). A summary list of important earthquakes would include the events of 1812, 1855, 1857, 1899, 1907, 1910, 1918, 1923, 1940, 1952, 1954, 1968, 1971, 1979, 1986, and 1987.

The reader is asked to consider not only the Richter magni.tude of significant pri.or earthquakes, given in Appendi.x A and available in the references quoted above, but also the Modi.fled Merca.l.li intensity designations for each event. Richter magnitude is a measure of the energy re.leased during an event at its source (the focus or hypocenterJ, whereas Modifi.ed Merca.l.li. i.ntensi.ty i.s a subjective measure which depends on the effects of an earthquake on life and property in a region near the epicenter during and immediately after an event. Thus, Modifi.ed Merca.l.li intensity and Richter magni.tude are impossible to relate precisely to each other, but Appendix B does given an approximate relationship for a papulated area near the epicenter.

Current seismological research and analysi.s is now utilizing a more fundamental magnitude scale than the Richter scale, based on the concept of seismic moment. Sei.smic moment is defined as the product of the area of rupture, the average amount of slip, and the shear modulus (or strength) of the rocks involved. A new magnitude scale, termed the moment magnitude scale (often indicated as Mr is approximated by the Richter magnitude scale devised for southern California, known as the local magnitude scale, for earthquakes in the magnitude ranges 3 to 7 (Ziony and Yerkes, 1985).

In my opinion, a review of all available data suggest clearly that it is very likely that southern California will experience a great earthquake, Richter magnitude of moment magni.tude 7 or 8, in the next few years.

Definitions for fault system, fault zone, fault, fault trace, and other related terms used in this report are given in Appendix C of this report (Hart, 1985, revised 1988).

~~--~··:-. '

' '

CLOPl~E GEOLOGICAL SERVICES i;l:l"llJIGl~~l Al'[) ~~llllll'lll!f;r<l"Al REl'Ullti A.,ll t.:VALIJATI\INI!

Steven Craig

'·· ' '

MAGNITUDE

m ••••••••.•••• 4.0 TO 4.9 C9 ............ 5.0 TO 5.9 C) ............ 6.0 TO 6.9

June 14 1989

Fault / --- _ ___,...........I

'

Page 6

\·. \ .

Scale 1 : l,000,000

' \ . ,..- \~., \\I •

... > .. '\ (!)

C!) -~~- .. ~--~~ ·.: __

One Inch EJ:iuals 15. 78 Miles

6 MicciJrum ~rted Intensity reported (prior to 19JO's}

Map ft 2. Base map from 1900

Earthquake from Real, to 1974.

epicenter map of vicin.ity of subject property. Toppozada and Park ( 1974) . Epicenters shown

CLOPINE GEOl-OGICAL SEftVU..:ES GEl~LOtlt:,l,L Al'ID l:'.!'l.,.IHll!'iMl'.NT4l, ~EJIQ~TS 4!'10 EV,l,LL'ATJ(ffl!f.

Steven Craig June 14 1989 Page 7

B. Seismic Considerations and Analysis

As described by Hart (1985, p.1), the Alquist-Priolo Special Studies Zones Act was signed into California State law on December 22, 1972. It has subsequently been amended four times. The purpose of the Act is to prohibit the location of most structures for human occupancy across the traces of active faults and to mitigate thereby the hazard of fault-rupture. The Act is codified in the Public Resources Code as Division 2, Chapter 7_5_

Any fault along which there has been surface displacement during the last ll,000 years (Holocene and Historic Epoch time) is defined by the California State Mining and Geology Board as an ACTIVE FAULT. These Holocene and Historic faults are considered to be the faults most likely to have renewed movement during the lifetime of any structures at a project site, and tt1us most likely for surface rupture.

Faults are defined as POTENTIALLY ACTIVE if they show evidence of surface displacement during Quaternary time (the last 2 million years).

I consider it very likely that significant earthquakes w.ill occur along the San Andreas or other faults in southern California during the lifetime of proposed structures at the subject property_ For this reason, it is very important that all persons involved with any proposed planned improvements at the subject site become familiar with the geological and engineering conditions at the site, in order that they should properly personally determine if the levels of geologic risk at the subject property are within their levels of personal allowable risk for their life and.property, and take every action possible that will mitigate the potential risk for other persons who may be at the subject site during future anticipated geological events.

Seismic considerations (and analysis) presented in this report should be provided to any person involved with future planning of proposed improvements at the subject site.

Seismic considerations involve the following topics:

l. Earthquake Recurrence Intervals 2. Maximum Credible Earthquake 3. Maximum Probable Earthquake 4. Maximum (peak) Rock Accelerati-0n 5. Repeatable High Ground Accelerations 6. Duration of Ground Shaking 7. Period of Bedrock Acceleration

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Steven Craig June 14. 1989 Page 8

l. Earthquake Recurrence Intervals

The earthquake recurrence intervals for the San Andreas, San Jacinto, and the Sierra Madre (Cucamonga) fault zones are given by Lamar, Merifeld, and Proctor (1973, p. 267) as:

Name of Fault:

Southern San Andreas San Jacinto System Sierra Madre System

Recurrence Interval !in years) at a point on the fault:

Richter magnitude 6 7 8

10 100 100

40 400 300

200 2000

800

Recurrence Interval (in years) over the length of the fault:

Richter magnitude 6 7 8

-3-1 4-10

30-100

3-10 40-100

100-300

40-100 1,00-1000

800

The above data are fairly consistent with more recent research, Ziony and Yerkes (1985) list the recurrence intervals for a major earthquake for a given point along the San Andreas and the San Jacinto as (table 11, P- 83): San Andreas: 65 to 270 years; San Jacinto: 30 to 150 years.

These data clearly indicate that a Richter magnitude earthquake of 6.0 or greater ia an expectable and probable event on the southern San Andreas, Banning, San Jacinto, or Sierra Madre fault in the near future_

2_ Maximum Credible Earthquake for Ordinary Plannin~ and Design Purposes

The maximum credible earthquake, as California Division of Mines and Geology maximum earthquake that appears capable of presently known tectonic framework. It believable event that is in accord with all seismologic facts ... "

defined by the (Note 43), is "the

occurring under the is a rational and

known geologic and

Ziony and Yerkes (1985, p. 80) state that an earthquake of moment magnitude 8 appears credible for the southern San Andreas fault for ordinary planning and design purposes, a moment magnitude 7 earthquake is resonable for the San Jacinto fault, a moment magnitude earthquake 6.5 is reasonable for the Whittier and Elsinore faults, a moment magnitude 6_5 is reasonable for other northwest-trending late Quaternary faults, and a moment magnitude 6.5 to 7_0 is reasonable for late Quaternary reverse faults of the Transverse Ranges.

CLOPINE GEOLOGICAL SE~VICES (;£.()U)li'.;li.;AL Al'jll 1:11\llR!JtllMl'.:l'jT..!,~ llr.J'llllnl Al'jD lo:\IALIIATlO!'j~

Steven Craig June 14, 1989 Page 9

3. Maximum Probable Earthquake

The maximum probable earthquake, as defined by the California Division of Hines and Geology (Note 43), is "the maximum· earthquake that is likely to occur during a 100-year interval. It is to be regarded as a probable occurrence, not as an assured event that will occur at a specific time."

Name of Fault:

San Andreas San Jacinto Sierra Madre (Cucamonga) Whittier-Elsinore

Maximum Probable Earthquake, Richter magnitude:

7_5 to 8 7.0 7.0 6.5

Earthquakes in the above Richter magnitudes would be considered as SEVERE.

4. Maximum (peak) Rock Acceleration

The maximum (peak) rock property, produced by a Richter earthquake, would vary as a (Greensfelder, 1974), as follows:

accelerati()n at the magnitude 7.5 maximum function of fault

subject probable distance

Fault Distance: Maximum (peak) Rock Acceleration:

2 5

10 20 so 70

miles miles miles miles miles miles

.73g

.57g

.43g

.27g _lQg .07g

s. Repeatable High Ground Accelerations_

According to Page et al., described by Ploessel and Slosson (1974, p. 195), a single peak of intense motion (maximum or peak acceleration) may contribute less to the cumulative damage potential than several cycles of less intense shaking. Repeatable high ground accelerations from ear·thquakes should be of important concern in structural design of proposed structures on the subject property_

Available data indicate the relationship between the (peak) rock acceleration and the repeatable high accelerations at the subject property as follows:

maximum ground

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Steven Craig June 14, 19B9 Page 10

Maximum (peak) Rock Acceleration Repeatable High Ground Accelerations from Earthquakes

.73g

.57g

.43g

.27g

.log

.07g

.47g

.37g

.28g

.l8g

.07g .OSg

6. Duration of Ground Shaking

The duration of ground shaking has never been rigorously defined, and is estimated in a subjective manner only (Greensfelder, 1974)_ However, the relationship between Richter magnitude earthquakes and the duration of strong phase shaking can be estimated (Housner, 1970, p. 79, table 4.3) as:

Richter magnitude Duration of Strong Phase of Shaking

5.0 2 seconds s_. s 6 seconds 6.0 12 seconds 6.5 18 seconds 7.0 24 seconds 7.5 30 seconds 8.0 34 seconds 8.5 37 seconds

7. Period of Bedrock Acceleration

Design criteria for buildings on the subject property should consider the predominant period of bedrock acceleration (Greensfelder, 1974), according to the following table:

Acceleration Zone (g)

0.5 0.4-0.5 0.3-0.4 0.2-0.3 O.l-0.2 0.05-0.l

Average Fault Distance (miles)

6.2 10.6 17.4 27.9 46.6 66.4

Predominant Period (in seconds)

0.35 0.35 0.35 0.35 0.40 0.50

l:LOPINE GEOLOGICAL SERVICES C.t;lll,fll;14.;u ~/'ID tl'll111RONM~AL REPOR'l'!I- AND E\IALUATIOl'li

Steven Craig June 14, 1989 Page 11,_

c. MetQods of Study

Principal fault zones and the general geology of southern California have been the subject of direct field research and laboratory study by the author since 1961. As a part of this investigation. published references describing the regional and local geology pertinent to the subject property were reviewed. Other published references were also consulted, and they are listed as Part V of this report. In addition, the following took place:

{1) first discussed the need for geological investigation of the subject property vicinity with Ms. Diane Ludovise, Project Manager for Craig Development Company of Newport Beach in January, 1988. As a result of these discussions, on-site preliminary field evaluation of the subject property vicinity was conducted during January, 1988. Of particular interest at that time was the 30 ~ acre parcel immediately east of the subject parcel of this investigation ·- that parcel now known as the Desert Hills Factory Stores Project.

(2) a geologic trenching report for the Desert Hills Factory Stores project was submitted by CJ.opine Geological on June 14, 1988. This geologic trenching report, together with an addendum by CJ.opine Geological dated July 25, 1988, together with a geotechnical evaluation by Leighton and Associates (1988), together with a response letter from Clopine Geological dated October 4, 1988 were submitted to the Riverside County Planning Department, Steven A. Kupferman, County Geologist. They were approved as satisfactory for Alquist-Priolo Special Studies Zones Act and Riverside County Ordinance No. 547 requirements by Mr. Kupferman on October 12, 1988. These reports described the adjacent 30·acre parcel immediately east of the subject property under discussion in this report. These reports and investigations were carefully re-studied and evaluated as a part of this investigation.

(3) a request and the subject parcel May 23, 1989.

authorization to complete the investigation for of this report was received from Steven Craig

(4) During the period May 23, 1989 and June 14, 1989, I have discussed various aspects of the project with Tom Grant and Bill Dettelbach of Grant General Contractors, Inc., Diane Ludovise of Craig and Associates, Kent Nelson of John Byerly. Inc .. and Charles Price, Certified Engineering Geologist.

(5) Geological field investigation was conducted on-site May 25, May 31, June l, 2, 3, and 4, 1989.

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Steven Craig June 14, 1999 Page _12

(6) On May 31, June 1, and June 2, 1989, a total of 923 feet of exploratory backhoe trenches were excavated on the subject property_ The trenches were backfilled and wheel rolled, with the aid of a water truck, on June 3, 1989. Backhoe operator was Lee Raub, of Raub Backhoe, and water truck operator was Randy Carnes of R. and D. Water Truck Services.

( 7) On May 25 di'scussions were held with Angelo "Duke" Guai·ino, who lives adjacent to the subject property on the north.

(8) on May 26 I discussed the project briefly by telephone with Mr. Steven Kupferman, Riverside County Geologist. and arrangements were made for an on-site visit June 1.

(9) on June l, during the afternoon, Mr. Benny Burke, Soils Technician (Geotechnical Engineers, Testing, and Burke observed the trenching-in-progress site materials, in preparation for soils

I discussed the project with for John Byerly, Inc., Inspection) on-site. Mr.

and the characteristics of testing to follow.

(10) Mr. Steven Kupferman, Riverside County Geologist, made an on­site visit on June 1, 1989. Following and during discussions on site geology, he inspected site excavations.

(11) Air photographs utilized during the investigation are identified as 5-24-74, photo numbers 193, 194, and 185.

(12) Review and evaluation of all appropriate references and field notes was complete prior to the preparation of this report.

CLOPINE GEOLOOICAL SERVICES Cl::.!ILtXilcq. A.f'll.I PR'lllUl'OaNTAL HEPOR'TII A~D EVALUATl(Jl'll

Steven Craig June 14, 1989 Page 13

III. RESULTS OF STUDY ·- SITE GEOLOGY

As discussed above, the subject property of this investigation is located in a complex geological setting, at the boundary of two great structural blocks of southern California, in close proximity to the San Andreas fault zone, north and south branches, and a fault trace of the San Gorgonio Pass fault complex was located on the subject property. Site geology is dominated by the tectonic uplift of the mountainous provinces north and south of the subject property. It is generally agreed that the formation of the high topographic relief was accomplished during the Pleistocene and Recent time (Di~lee, 1982a, p. 22).

!\....,,. Rock Types

As exposed in trench excavations, Quaternary alluvial deposits (Qal) are exposed over the whole of the subject property. These deposits consist of silt, sand, gravel, and cobbles, 1n the manner shown on the trench logs of this report. Some areas of the subject property may have minor clay deposits, as reported observed on the Desert Hills Factory Stores Project approximately 1/2 mile east of the subject property of this investigation by Charles Springer of the California Regional Water Quality Control Board, infor·mation contained in a letter to Clopine Geological dated June 7. 1989 from Diane Ludovise of Craig and Associates. Judging from the character of the deposits, it is my opinion that all deposits are Holocene in age.

Overlying these Holocene alluvial deposits are very scanty and discontinuous deposits of Recent sand, forming small hillocks. These eolian deposits are in active transport and modification at the present time. Also overlying these Holocene alluvial deposits are discontinuous deposits of modern fill and junk, especially in the eastern portion. Rattlesnakes are abundant in the junk tires.

A Holocene age for the sediments seen in excavations is indicated by:

l. Lithologic character of the rock units a) no increase in density of sediments with depth b) clasts of granitic and granite gneiss are unweathered c) topsoil is very poorly developed d) sediments unconsolidated, lithification poor

2. Prior geological mapping 3 Geologic setting of the site

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Steven Craig June 14 1989 Page 14

The overall character of Holocene alluvium seen in trench excavations is described as follows:

all portions moderately loose and unconsolidated, phenoclastic, predominately silt, with sand, granules, pebbles, cobbles, no clay observed, thickly bedded to moderately thickly bedded, light yellowish brown to yellow brown (major units on trench logs have Munsell soil color designations), clasts are granitic and gneissic rock types derived from the Transverse Ranges north of the site, occasional gabbro and marble clast, clasts unweathered and fresh, sub-angular to sub-rounded, exposures dry (except slightly damp in trench lA just south of fault (reason unknown)_ No free groundwater present. Sediments deposited by running water and mudflow; some mudflow deposits biased in favor of larger clast sizes as fines are removed by subsequent sheetwash_

B. Structural Geology

An active trace of an un-named fault of the San Gorgonio Pass fault complex was located during this investigation, as shown on Map # 3 of this report. Following initial location by Trench # 1A of this investigation, four additional trenches were excavated (Trenches 18, lC, 2, and 3) to more precisely determine the location and character of the fault. The fault was again observed present in trenches lB and lC, as shown on Map # 3 and the trench logs. No fault was observed in Trench # 2_ Trench # 3 was excavated for the additional purpose of looking closely at subsurface conditions adjacent to a small right-lateral bend of a small drainage channel across the subject property. No fault was seen in Trench # 3.

The fault was located in approximately the location shown by Matti, Morton, and Cox (1985), however, the trace of the fault is apparently just north of the majority of the property under discussion.

The fault appears to be right-lateral strike-slip and reverse (shallow thrust) in character.

Trenches # 4 and # 5 were excavated additional fault traces transect the subject of faulting was seen in these trenches_

to determine if any property. No evidence

CLOPINF. GEOLOGICAL SERVICES (;UILIIC;ii:J.L "~II t:llVlll!l:'\liE.'11'A~ HU'ORn Al"ll t.fALllATlllM,11;

Steven Craig June 14. 1989 Page 15

Additional trench excavation information pertinent and useful to the subject property was utilized as a part of this investigation. This information was: (1) the trench log and report of Rasmussen (1980) for the Desert Hills Cabinet Building (DHCB) as shown on Map t 3 of this report and (2) excavation information obtained during the study for the Geologic Trenching Report for the Desert Hills Factory Stores project by Clopine Geological, dated June 14, 1988.

No faulting was seen in the Rasmussen (1980) trench. No faulting was seen in the excavations by Clopine Geological (1988) that indicated a trend toward the subject parcel.

Tectonic forces across the subject property are noted to be both compressional and shear in nature, as indicated by the mapp.ing of Matti, Morton, and Cox 1985). Based on the fact that the fault cuts very young alluvial sediments, I would judge the fault to be an active fault. The fault does not appear to cut the uppermost brown silt and sand (referred to as topsoil by Rasmussen (1980), and it is unlikely that the fault has caused surface disruption in historic time (the last 200 years).

C. Ground Watel'.'.

The subject property is located in the Cabazon Storage Unit of the San Gorgonio Pass sub-basin of the Coachella Valley Ground Water Basin (Leighton, 1988, p. 3). Ground water would be expected in excess of 500 feet, based on Leighton, (1988,p. 3) and results of drilling on the Desert Hills Factory Stores project to the east.

D. Drainage

Surf ace flow across the subject property is mainly confined to three small intermittent drainage channels. Development grading plans will need to take into account (1) high volumes of surface flow following the infrequent but intense thunderstorms typi(;al of this region of California and (2) increased impervious surfaces prepared during development of the property.

E. Slope Stability. Landsliding

Landsliding is not considered a potential hazard on the site due to the planar surf ace of most of the property and grading plans which I understand will reduce considerably the 3 to 8 degree

·regional slope that is now present.

C:WPIN'f, GEOLOGICAL :!iERVICF.f; ~•:ouwa~~I.. 11.~u ltl'l~11Ullt'lllU\'1'1t.L JU'1'fll!TI ~f'l> E'l'uu~TlllH.'I

Steven Craig June 14. 1989 Page 1~

F. Surface Fault Rupture/Fault Hazard

An active fault trace was located as a part of this investigation and this trace has the potential for surface fault rupture. A 60-foot setback zone is reco1DJBended for this fault. {See Reco11U11endations).

G. Ground Subsidence

The soils engineer should make recommendations concerning possible minor ground subsidence for foundation considerations. The hazard from seismically-induced ground subsidence is considered very low.

H. Seiche. Lava Flow. Other Volcanic Hazar<L_ Tsunami

Hazard from these risks is considered to not be present.

I. Seismically-Induced Flooding

No water tanks exist up-slope at present. Should any tanks be placed on or to the north of the site, the inundation path should be calculated should the tanks fail.

J. Lurching

Lurching is common on steeper slopes where intense horizontal accelerations causes dynamic slope failure. Slopes on the property indicate the potential for lurching is low.

K. Liquefaction; Lateral Spre~9ing

Due to the depth to ground water in the hundreds of feet, the potential for seismically-induced liquefaction is considered very low to nil. As liquefaction is considered very un-likely, hazard from downhill lateral spreading is also considered very low.

CLOPINE GEOLOGICAL SF..ltVlCES GFA~t!Gltu A.MU Jo:.~VIRl)ll'~[~TAL Rl::P01t1:i A~n r.\'!LLll~TIOl'I~

Steven Craig June 14. 1989 Page :). 7.

III. CONCLUSIONS

1_ A portion of the subject property is located in an Alquist­Priolo Special Studies zone, as defined by the State Geologist, and provisions of the act apply to ·that portion of the subject parcel. In my opinion, greater seismic risk exists on properties located in or adjacent to such Special Studies zones.

2. All portions of the property were geologically evaluated by on-site study, including exploratory backhoe excavations and analysis of aerial photographs. An active trace of the San Gorgonio Pass Fault zone was located as a part of this study, as shown on Hap # 3 of this report. A 60-foot setback zone on both sides of this fault trace is recommended, as shown on Hap # 3. No other zone of active faulting was identified on the subject parcel.

3. Therefore, (see item 2., above) in accordance wi.th accepted practices and understandings concerning acceptable levels of allowable risk, according to provisions of the State of California law and County of Riverside requirements, development of the subject property is considered to be feasible, provided that the recollU!lendations of this report and related reports are followed.

4. All topics described in Section II of this report, as SITE GEOLOGY, are also included here as conclusions.

5. Due to the local and regional seismic setting of the subject parcel, there exists a high potential for severe seismj,c shaking of the subject property during the lifetime of proposed improvements. Due to the presence of an active fault on the subject parcel, there exists a high potential for surface ground rupture within the 60-foot setback zone on each side of the fault trace during the lifetime of proposed improvements.

6. The subject property geological standpoint, to most Pass area.

is considered as typical, from a of the acreage in the San Gorgonio

7. This investigation involved field on-site and exploratory trench study, regional and vicinity geological evaluation, analysis of maps, reports, aerial photographs, personal notes and maps, and was thus conducted according with geologic guidelines and law of the State of California and Riverside County. Therefore, this study was conducted according to normal and reasonable geologic procedure. This report has been prepared for the exclusive use of Mr_ Steven Craig, or any person designated by him for the specific application to the subject property under discussion. Our professional services have been performed, our findings obtained, and our conclusions and recommendations prepared in accordance with generally accepted geological principles and practices. This warranty is in lieu of all other warranties eith~:r_ expressed or implied.

CLOPINE GEOLOGICAL SERVICES i.;1:u1111;1CAL AJ\111 i:!Wll.UIV"'E/jTAL llP'lllllTII M!'D E¥UUA'f1UMI

Steven Craig ___ _,.J_,,u,,_n,_,e"-'1._4.....__,,1_,,9"'8"'9'----------------Pq_g!;t_ta

IV. RECOMMENDATIONS

1. The location of the exploratory trenches of this investigation should be located by Sanborn-Webb, Inc., following their field survey of trench locations conducted June 2, on a suitable large­scale iaap, and the location of the fault trace in trenches lA, lB. and lC should al.so be shown. A setback zone of 60 feet on each side of the fault trace should be indicated as a zone 120 feet wide where construction of structures for human occupancy are prohibited.

2. The trenches of this investigation were backfilled. and wheel­rolled extensively, with abundant use of water, but have not been inspected to my knowledge for determination of their compaction relative to undisturbed materials. They should be so inspected for coiapaction, and the recoiamendations of the soils engineer followed.

3. Seismic information contained in this report should be considered by the structural engineers responsible for structural design of proposed iiaproveiaents.

4. Property owners and tenants of proposed improvements, present and future, should be made aware of the seismic risks involved with properties in close proximity to active faults, and these persons should consider the information in this report to determine if the anticipated Richter magnitude, moment magnitude, and Modified Mercalli intensity designations, given as probable, are au;eptable levels of risk for their life and property.

5. It is recoiamended that a Registered Geologist review project grading plans. It would also be recommended that a Registered Geologist be on-site during grading to properly evaluate any geological conditions that may be exposed during grading.

6. Should any conditions be appear in any way to be report, I s uld be notified recomme ·.p...._, prepared .

' " "'--U,

encountered during different from those

illl!llediately in order

~s (\;. ""'(j ~)'(.. ,,.. <r\ .,, "-~ -'J., .

* GORDON A

CLOPINE NO- 511

* Respectfully submitted,

Gordon A. Clopine Registered Geologist State of California

development that described in this that appropriate

13093 Burns Lane Redlands, CA. 92373 (714) 794-6700 Certified Professional Geologist No. 6125

CLOPINE GEOLOGICAL SERVICES (J!:.OLI11;11:41. A,.~D ):;lj~lilut'4Mr.fl'TAL REPOltT'1 .1.~111:vuu~TIOr-t'J

St~ven Craig June 14 1989 Page 19

V. REFERENCES

Alfors,J., Burnett, J., Gay, plan for California:

T. Jr., 1973, Urban geology master California Division of Mines and

Geology Bulletin 198.

Allen, c., 1957, san Andreas fault southern California: Bulletin of America, v. 68, p. 315-350.

zone in San Gorgonio Pass, the Geological Society of

Allen, C., St. Amand, P., Richter, C., and Nordquist, J., l.965, Relationship between seismicity and geologic structure in the southern California region: Bulletin of the Seismological Society of America. v. SS, no. 4, p. 753-· 797.

Bloyd, R. Jr., 1971, Underground storage of imported water in the San Gorgonio Pass area, southern California: United States Geological Survey Water Supply Paper l.999-D.

Bonilla, M., l.970, Surface Earthquake Engineering, chapter 3, p. 47-74.

faulting and Robert Wiegel,

related effects: ed., Prentice Hall,

Borcherdt ,. R. D. , 198S, Predicting earthquake ground motion, an introduction, in Ziony, 1985, cited below.

Bortugno, E.J., and Spittler, T.E., 1986, Geologic map of the San Bernardino quadrangle: Map No. 3A (Geology), Regional Geologic Map Series. California Division of Mines and Geology, scale: l:2SO,OOO.

Brown, W.M., Kockelman, W.J., and Ziony, J.L., Editors, 1986, Future directions in evaluating earthquake hazards of southern California: United States Geological Survey Open­File Report 86-401, p. 1-421.

Byerly, J., 1988, Foundation Investigation, Desert Hills Factory Stores, Seminole Drive at Millard Pass Road, Cabazon, California, Report No. 2886, File No. S-7276.

California Division of Mines and Geology: Note #37, Guidelines to geologic/seismic reports. Note #43, Reco111111ended guidelines for determining the

maximum credible and the maximum probable earthquakes.

Note #44, Recommended guidelines for preparing engineering geologic reports.

Note #46, Guidelines for geologic/seismic considerations in environmental impact reports.

CLOPINE Gt:OLOGICAL .SERVICE..'i r.l'~l~l(;lt;i1.L i1.~!)b!\"Jlll>f"~l:::.'ITAL IU".l"llllTll 4rtD El'ALUi1.'tltlH!I

Steven Craig June 14, 1989 Page 20

California Division of Mines and Geology, continued: Note #4B, Checklists for the review of geologic/seismic

reports_ Note #49, Guidelines for evaluating the hazard of surface

fault rupture.

Clopine, G. , 19BB, Geologic Trenching Report, 30--acre site northwest of Hillard Pass road and Seminole Drive, vic:inity of Cabazon, project 52088, RiVel'Side County Geologic Report No. 542. with Addendum, dated July 25, 1988.

Crowell, J., 1975, San Andreas fault in southern California: California Division of Hines and Geology, Special Report 118.

Davis, J., et al., 1982, Earthquake planning scenario for a magnitude 8.3 eal'thquake on the San Andreas fault in southern California: California Division of Mines and Geology Special Publication 60.

Dibblee, T. Jr., 1975, Late Quaternary uplift Bernardino mountains on the San Andreas faults,in Crowell, J., 1975, p. 127-135, cited

of the San and related above.

-----1982a, Regional geology of the Transverse Ranges province of southern Cal1fornia, in Fife, D., and Minch, J_, Geology and Mineral Wealth of the California Transverse Ranges, P-7-26, cited below.

-----1982b, Geology California, in Wealth of the cited below.

of the San Bernardino mountains, southern Fife, D., and Hlnch, J., Geology and Mineral California Transverse Ranges, P- 148-169,

Dick1nson, W., and Grantz, A., 1968, Proceedings of conference on geologic problems of the San Andreas fault system: Stanford Un1versity Publications, Geological Sciences, v. XI, Stanford University, Stanford, California.

Everenden, J.F., and Thomson, J.M., 1985, intensities: 1n Ziony, 1985, cited below,

Predicting seismic p. 151-202_

Fife, D. , and Minch, J. . 1982, Geology and mineral weal th of the California transverse ranges: South Coast Geological Society Inc., Santa Ana, California_

Fumal, T.E_, and Tinsley, J.C_, 1985, Mapping shear-wave velocities of near-surface geologic materials: ln Ziony, 1985, cited below, p. 127-149/

CLOPINE GEOI,OGICAL SF.fl.Vlf...:ES C.l~ULOGH:AI, ANIJ ~lWUtUJlll"lt:l'IT.4.1. RF:,...)11"~ Al'IU r.n.i.,u"T~Lll'CI

Steven Craig June 14. 1989 Page 21

Greensfelder, R., California

1972, their

calif ornia Division of 37_

Crustal movement history, data, Mines and Geology

investigations in and significance;

Special Publication

------1974, Maximum credible rock earthquakes in California:

accelerations from California Division of Mines and

Geology Map Sheet 23.

Harden, J., Matti, J., and Terhune, C., 1986, Late Quaternary slip rates along the San Andreas fault near Yucaipa, California, derived from soil development on fluvial terraces: Geological Society of America Abstracts with Programs, Cordilleran Section. page 113.

Hart, E .. 1985, Revised 1988, Fault-rupture hazard zones in California: California Division of Mines and Geology Special Publication 42.

Hope, R., 1969, Maps showing recently active breaks along the San Andreas and related faults between Cajon Pass and Salton Sea, California: United States Geological Survey Open-File Report, scale 1:24,000.

Housner, G., 1970, Strong ground motion, Earthquake Engineering: Prentice Cliffs, New Jersey, p. 75-92.

in Weigel, R., 1970, Hall, Inc. , Englewood

Jennings, C., 1973, State California Division 13, scale 1:750,000.

of California fault and geologic map; of Mines and Geology Preliminary Report

-----1975, Fault map of California with thermal springs, and thermal wells: Mines and Geology, scale 1:750,000.

locations of volcanoes, California Division of

Kovach. R., and Nur, A., 1973, Proceedings of the Conference on Tectonic Problems of the San Andreas Fault system: Stanford University Publications, Geological sciences, v. XIII. Stanford University, Stanford, California.

Lamar, D., Merifield, P., and Proctor, R., 1973, Earthquake recurrence intervals on major faults in southern California. in Moran. D., et al., cited below, P- 265-276.

Leighton, and associates, 1988, Geotechnical evaluation for E.I.R. purposes, 30 acre site, northwest of Millard Pass Road and Seminole Drive, vicinity of Cabazon, Riverside County, California: Project No. 6880696-01.

CLOPlf\IJ=; GEOLOGICAL SERVICES· (;E.\M..J..l(;t<.:~L. M'ID >:.'11Ylft(.1111"1~TAI. Rl:;HlllTII A~D HALl!A1101'l.'I

Steven Craig June 14, 1989 Page 22

Lung, R., and Proctor, R., 1966, 1969, Engineering Geology in southern California: Special Publication, Association of Engineering Geologists, Arcadia., California.

Matti, J., Morton, D., and Cox, F .. , 1985, Distribution and geologic relations of fault systems in the vicinity of the central Transverse Ranges, southern Cal:ifornia: United States Geological Survey Open-File Report 85-365.

Moran, D .. et al., 1974, Geology, Seismicity, and Environmental Impact: Special Publication, Association of Engineering Geologists, University Publishers, Los Angeles, California.

Moran, L., 1975, Active California Division 47.

Fault Mapping and Evaluation Program: of Mines and Geology Special Publication

Munsell Soil Color Charts, 1988, Macbeth Division of Killmorgen Instruments Corporation, Baltimore, Maryland.

Ploessel, M. and Slosson, J., 1974, Repeatable high ground accelerations from earthquakes: California Geology, v. 27. no. 9, p, 195-199.

Rasmussen, G., 1980, Subsurface engineering geology investigation of a 76' X 210' building, north of 48510 Seminole Drive, in the nw 1/4 of sec 7, T3S, R2E, SBB&M, Riverside County, California. Project No. 1578.

Riverside County Comprehensive Plan, Geologic-Seismic Map.

Real, C., Toppozada, T., and Parke, D., 1978, Earthquake Epicenter Map of California: California Division of Mines and Geology Map Sheet 39.

Schnable, P., and Seed, H., 1973, Accelerations in rock for earthquakes in the western United States: Bulletin of the Seismological society of America, v. 63, no. 2, p. 501-506.

Sherburne, R. . Boylan, R. , and Parke, D. , California: California Geology, v. 38,

1985, Se.ismici ty of no. 4, p. 75-80.

Shearer, C.. coapiler, 1986, workshop on special study areas in southern California: National Earthquake Prediction Evaluation Council Special Report 1 , United States Geological survey Open-File Report 86-580.

South Coast Geological Society, 1982, Geologic map of the Banning (15 minute) quadrangle, 1:62500, compiled and mapped by Thomas W. Dibblee, Jr., Edited by Arthur Brown, SCGS 2.

Sykes, L. . and asperities, Geology, v.

(;LOPINE G~OLOGICA(, S~RVICES ~.t.ULIN;lt:AI. AN(I [.'.1 lllUl'OIV.NTAL ilt:..UK"D AND l:\'.<LL'~ TIO!'<~

Seeber, L. , 1985, Great San Andreas fault,

13, P- 835-838.

earthquakes and great southern California:

Taylor, C., and Cluff, L., 1973, Fault activity and its significance assessed by exploratory excavation, if\ Kovach, R. and Nur, A. cited above, p_ 239-247.

Tinsley, J.C. , sedimentary response: iQ

and Fumal, T.E., 1985, Mapping Quaternary deposits for areal variations in shaking Ziony, 1985, cited below, p. 101-125.

Tinsley, J.C., Youd, T.L .. Perkins, D.M. Evaluating liquefaction potential: below, p_ 263-315.

and Chen, A.T.F., 1985, in Ziony, 1985, cited

Toppozada, T., Real, C., and Pierzinski, D., 1979, Seismicity of California: California Geology, v. 32, no. 7, p. 139-142.

Toppozada, T. , Real , C _ , and Parke, D. , 1986, Earthquake history of California: California Geology, v. 39, no. 2, p. 27-33.

United States Geological Survey, 1987, Recent reverse faulting in the Transverse Ranges, California: United States Geological survey Professional Paper 1339, p. 1-203.

Vaughan, F., 1922, Geology of the San Bernardino Mountains north of San Gogornio Pass: California University Publications in Geological Sciences, v. 13, p. 319-411.

Wallace, R., 1970, Earthquake Andreas fault: Geological 81, p, 2875-2889_

recurrence intervals on the San Society of America Bulletin, v.

Weldon, R. and Sieh, K., 1985, Holocene rate of slip and tentative recurrence interval for large earthquakes on the San Andreas fault, Cajon Pass, southern California: Geological Society of America Bulletin, v. 96, p. 793-812.

Wilson, R.C., and Keefer, D.K., 1985, earthquake-induced landsliding, 317-345.

Predicting areal limits of in Ziony, cited below, p.

Yerkes, R.F., 1985, Geologic and Seismic Setting,: in. Ziony, 1985, cited below, p. 25-41.

Ziony, J.I., Editor, 1985, Evaluating earthquake hazards in the Los Angeles region ~ an earth science perspective, United States Geological survey Professional Paper 1360, p. 1-505_

Ziony, J.I_ and Yerkes, R.F_, 1985, Evaluating earthquake and surface-faulting potential: in Ziony, 1985,cited above,p.43-91

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n San (",abriel M:>untains E_J Block - granitic and

:retam:m:ihic rodes

ra:>logy after Matti, fur ton ! and Cox, 1985, u.s.G.s. epen \' Pile Rep::lrt 85-365, sheets 1 and 2 i

_..,.. ...... AND ..._-----

••••

- --

contact

fault.with ar=is ~or relati'lle' noverer

ttuust fault barbs on upper pl.ate

U = UC D = cta.lrl

faults as shown by Matti Morton and Cox

faults fran !uquist-Priolo State Map

-0_ MON .. 6 ON; w;s' '/_1 NG T 1'C S

Sr+' -------f-____ --------.:::_ !;"

f 7 ------- i

' 5

?06.5. 0 ---..( -·- -

/_ /

)

..____

'"'----

SITE MAP1

Quaternary (Holocene)

Alluvium

Qal

~·

' ~-"I

. ..--' f' I " / .! "'-, ,

0.88

Page 24

Llntr -

\ --r \.204f!~t

/\ .

Steven Craig June 14, 1989 Page 30

APPENDIX A

l'TonW>ent eonhQUak"5;,, C.Hfomia, 1769 tt>rough September 197' (Intensity VIII ""d above)

Dote

28 Jul' T769 8 Dec 1812

21 Dec 10 Jun 1836

Jun 1838 10or11 Jul 1855

9 Jan 1857 26 Nov 1858

Nov 1860 3 Jul 1861 1 Oct 1865 8 Oct

21 Oct 1868 26 Har 1872 19 Apr 1892 21 Apr

4 Apr 1893 20 Jun 1897 14 Apr 1898 22 Ju 1 1899 25 Dec

27&31 Jul 1902 18 Apr 1906 28 A?:" 28 Oct 1909 11 Jan 1915 22 Jun 21 Apr 1918 21 Jun 1920 10 Har 1922 29 Jun 1925 22 Oct 1926 20 Aug 1927

4 Nov 25 Feb 1930

1 Mar 6 Jun 1932

10 Har 1933 7 Jun 1934

18 May 1940 30 Jun 1941 15 Mar 19:,5 29 Jul 1950 21 Jul 1952 22 Aug 25 Apr 1954 21 Dec: 12 Sep 1966 e r.;:,.. 1968 I Oct 1969 9 Feb 1971

Region

Orange County, near lrvlne •• Southeni Cal ifornla. • • • • • Off coast of southern California Hayward fault, Berkeley. . . San Fran~isco region, San Andreas fault. Los Angeles County Fort Tejon-Carrlzo Plain San Jose . . . Humboldt Bay ••• Neai Li~errrore • Fort Humboldt-Eureka area. Santa Cruz Mountains Hayward. • • Near Lone Pl ne Vacaville. \Jinters. . North~eot of Los Angeles Near Hol 1 ister Mendocino area San Bernardi no County, San Jacinto-Hemet area Santa 3arbara County . San Francisco region Brawl~, Imperial Valley Humbolci~ County. • . Los A l.amos • • • • El Cent~o-Calexi~o~Mexicali area San Jacinto-Hemet area Inglewood. • • Chola""' Valley Santa aarbara area Monterey Bay ... Humboldt: Bay West of Point Arguello .. Westmorland. • • Bra,.Jey. . •• Humboldt County . Near- Long Beach. Parkfi., Id. . •• Imperial Valley. . Santa Barbara-Cii.trp i nteri a area Nort~ of Walker Pass lmpel""ial Valley .. Arvin-Tehachapi .•• Bake..Sfield •••.. East of Watsonville. Eu re~ • , . • T rocl<ee. • • • • • Na~th~!5t San Diegc County Santa Rosa • . . . • ~ San Fe 1.nando • ... . . • ~ .

*

Richter M.egnin.de

. Possibly 8

Possibly 8+

6.25. 6.8

6.5 6.3 6-6.9

7.5 5.0 4.5 6.4 6.3 6.0 7. 1 5-9 6.25. 5-5 7,7 . 5.8 5.25. 6.6 6.6 6.5 5.7 6.5

Modifibd Men:;.;alli Intensity

.VI 11-IX

.x • I X-X

.x

.VI 11 · .X-XI .VI 11 • VI I I • VI 11 .VI 11-IX , VI 11-1 X . I X-X .X-XI • IX • IX • VI 11-IX • VI I I • VI 11 -IX • VI 11 • IX • VI 11 .XI • VI 11 • VI 11 • VI 11 • VI 11 • IX .VI 11 • IX • VI I 1-1 X . Vl 11 • V 11 I , I X-X . VI 11 .VI 11 • VI I I . IX • VI 11 . x .VI 11 • VI 11 • VI 11 .XI • VI 11 • VI 11 • VI I • VI I I , VI I _v11-v111 . VI I 1-Xl

SCilJRG: c~_lif-:-rni"'.=1. G~01o:;r 1 ~Iovt:'lber 1971, pu.bli.;;Ued ~:i-· Ctli.!'or~a

r::.."71...?ion of l·~~.s and Geo.lcgy.

Steven Cra:ig June 14, 1989 Page 31

APPENDIX B

MODIFIED MERCALLI INTENSITY SCALE OF 1931

Tho fin! scalo to refioct earthquake interu:itios was d"" veloped by de Rossi of Italy, and Ford of Swit••rland, in the 1880•. This scale, with values from I to X was used for about two decades. A need for a more refined scale in­creased with the advancement of the science of .seismology, and in 1902, the Italian soisrnologist, Mercalll. devised a new scale on a I to X11 range. The ~fc.rcalli Scale was modi~ fied in 1931 by American seismologists Harry 0. Wood and Frank Neumann to take into account modem structural features:

I Not felt except by a very few under especially favor­able circumstances.

II

Ill

IV

v

Vil

Felt only by a few persons at rest, especially on upper floors of buildingS. Deucately su•pcnded ob· jeets may swing.

Felt quite notiCcably indoors, especially on uppe:r floors of buildingS, but many people do not recog· niz.e it as an ea.Ithquake. Standing motor cars may rock sl.ighC!y. Vibration lll<e passing of truck. Du.ration estimated.

-~ During the day felt indoors by many, outdoors by few. At night some awakened. Dishes1 windows., doors distw-bed; walls :make cracking sound. Sensation lll<e heavy truck striking building. Stand· ing motor cars rocked noticeably.

Felt by nearly everyone, many :a.wakened. Some dishes1 windows, etc. 1 broken: a few instances of cracked plasterj unstable objects ovcnurncd. Distur-­bances of trees, poles. and other tall objects some. Um.es noticed. Pendulum clocks may stop.

Felt by all, many frightened and run outdoors. Some heavy fumiture movtdi a few instant:l!:S of fallen plaster or damaged chimneys. Damage slight.

Everybody runs outdoors. Damage n<glillible in buildingS of good dcoign and construction; slight to moderate in well-built ordinary structures; consider­able in p0orly bui1t Ol' badly designed structures; some chimneys broken. Noticed by persons driving motor cars. •

VIII Damago slight in spocially desipiod structures; con­sidorablo in ordinary substantial buildings, with par­tial collapse; groat in poorly built structures. Panel

· wall.s thzown out of frame structures. Fall of chim­neys, factory stacks, column.sj monuments, walls. Heavy furniture overturned. Sand ilild mud ejected in small amounts_ Changes. in well water .. Persons driving motor cars disturbed.

IX Damage considerable in spcc:ially desipiod strue­tures; wcll·design.ed frame structures thrown out of plumb; great in substantial bu~dings, with partial collaP5•· Buildings shifted off foundations. Ground cracked conspicuously. Underground pipes b•okon.

x

XI

XII

Some well~built wooden structures destroyed; most masonry and frame: structures dest:royed with foun­dations; ground badly cracked. Roils bent. Land­slides considerable from river banks and stcci:: slopes. Shifted sand and mud. Water splashed (slopped) over banks.

Few, i.f any, (masonry) structu:res remain.standlng Bridges destroyed. Broad fissures in ground. Under· ground pipelines. completely out of service. Ea.rtt slumps and land slips in soft ground. Rails bcn: greatly.

Damage total. Practically all works of constructio• are damaged greatly or destroyed. Waves seen or ground surface. Lines of sight a.nd level arc dis tortcd. Objects are thrown upward into the air.

COMPARISON OF MAGNITUDE AND INTENSITY

It is difficult to compare magnitude aniJ intensit because intensity is linked with the particular ground an structural conditions of a given area, as well as distanc from the earthquake epicenter, while mag.n.itude is a 1ne: suri: of the ener~ released at the focus of the carthqu.i.l

Richter Magnitude

2

3

4

5

6

7

8+

Ex pt:~ted Mod ifie~ ~1 etcalli Maximum Intensity (at epicent~r)

Hl Usu a 11 y d <Ce cl e d only by instrument~

Ill Felt indoors

IV··V Felt by most people; slignt damage

Yl·Yll Felt by all; many

frightened and run outdoorSj damage minor to moderate

VII-VIII Everybody runs outdoors; damage moderate to maJor

IX-X

X-Xll

Major damage

Total and major da.magc

After Charlc:s F. Richter1 1958, Elementary Sl!i.rmolog

CJH/1·72 Modi/itd f">m USG

APPENDIX C

FAULT-RUPTURE HAZARD ZONES IN CALIFORNIA

By Earl W. Hort

INTRODUCTION

The Alquist-Priolo Special Studies Zones Act was signed into law December 22, 1972, and went into effect M.areh 7, 1973. The Act, codified in the Public Resources Code as Division 2, Chap­ter 7.5, has been amended four times. A complete text of the Act is provided in Appendix A. The purpose of this Act is to prohibit the location of most structures for human occupancy across the traces of active faults and to mitigari: !hereby the hazard of fault·rupturo (Section i6i )_5) _

Under the: Ae1. the State Geologist (Chief of the Division of Min~ and Geology) is r~quired to delineate ··special studies zones .. along known active faults in California. Cities and coun­ties affected by the zones musl ri:gulate certain development ··projects'" wi1hin the zones. They must withhold development permits for sites within the zones until geologic investigations demonstrate rhat the sites are not threalcned by surface displaceT mcnt from future faulting. The Shi.le Mining i'tnd Geology Board provides a.dditional tegulations (Policies and Criteria) to guide cities and counties in their implementation of the law (California Admi11is1ra1ive Code, Title 14, Div. 2, Chap. B, Subc:hap. 1, Art_ 3). A summary of the principal responsibilities. and functions required by the: AlquistTPriolo Act arc given in Table 1. The Policies and Cri1~I'ia are sumrn.ari.ted in Table 2, and the com­plete lext is. proYided in Appendix B.

This publication identifies and describes (I) actions taken by 1he St~te Geologist to delineate Special Studies Zones, (2) poli­cies used to make zoning decisions, and (3) Official MapS of Special Studies Zones issued to date. A continuing program to evaluate faults fot furure zoning or z.one revision also is summa­ri.zed. Other aspects of the AlquistTPriolo Spc:cial Studies Zones Act and its implementation are discussed by Hart ( 1978).

Inform.a.'1ion ptesentcd hctc is. based on various in-house docu­ments and publications of this author and 01her5 of the Division. The principal publications arc cited in 1he list or references. The assistance of Perry \\'ong (compilation of faults on Figure 4), Rk:ha.rd R. Moa.r (drafting), Jon Lloyd (editing), and olher technical and clerical staff of the Division in revising I his rep-Ort is gratefully acknowledged.

Tab/11 1. Summory of reipon1ibiliti~!I t:Jru:/ functions undttr the AJT q11l1r-Priofo Sp~eial Studitts Zantts Act ( stttt Applffm:J;~ A for f1JI/ t~xt of ActJ_

Stole G,,alagist

1. Delineates Special Studies Zones: compiles and issues maps to cities, counties, and state agencies (S«:. 2622). a. Preliminary Review Maps. b. Official Maps.

2. Reviews new data (Sec. 26Z2)-a. Revises exi!i.ting ma.ps. b. Compiles new maps.

3. Approves. requests for wajvers initiated by cities and counT ties (Sec. 2623).

State Mining and ~ology Board

1. Formulates policies and criteria to guidt: cities and counties (Sec. i62 l.5 and 2623)- (Seo Appendix B.)

2. Serves as Appe.i.ls lloard (Sec. 673).

Cities and Counties

1. Must adopt 2:.oning laws, ordinances, rules, and regulations; primary responsibility for irnplc=menting Act (Sec. 2621.5).

2. Regulates speeified "projects" within Special Studies Zones (Sec. 2623)-a_ Detenn.ines need for geologic rep0rts prior to project

development. b. Approves. geologic repons prior to issuing development

permits. c. May initiate waiver ptocedures. (S~ Appendix D.)

3. May charge reasonable fees for a.dminis.lrative co5ts (See. i62~)-

Other

I. Seismic Safety Commission - advi$es St.att: Geologist and State Mining and Geology lloard (Sec. 2630).

2. St.a.t~ Ag~:ncies ~ prOhibited from siting structures across a.c:tive fault traces (Sec. 2621-5).

3. Disclosur~ ~prospective buyers of any real property locatr ed within a Special Studies Zone must be notified of that fact (Soc. 26it. 9) _

Steven Crai.g June 14. 1989 Page 33

Tobia 2. Summary af policitu g,.,d i:rif~da adopft:d by th~ Sfot~ Mining end G~ofogy Board in Cr:iliforl'lia Admini1trative Codi! ( !.~i! App~ndix B for fuJI fexf}.

Policies

L Defines active fault (equals p0tential hazard) as a fault that has had surface displacement during Holocene time ( las.t 11,000 years).

2- Defines .. structure for human occupancy" and other lenns.

3. Provides opportunity for public to comment on Preliminary Review Maps. of Special Studies Zones.

4. Provides. for comments and recommendations to State Geol­ogist regarding Preliminary Review Maps.

Sp<cific Criteria

I. No structures for human occupancy d~fined. as a "project" are pennitted on the trace of an active fault. Unless proven otherwise~ the area within 50 .feet of an active fault is pre­sumed. to be underlain by an active rault.

2. Requires that buildings converted to structures for human occupancy comply with provisions or Act

3. Requires geologic rep0rts directed at the problem of poten~ tial surface faulting for all projects defined by the Act.

4. Require5 cities and counties to review geologic rep0rts for •dequacy.

5_ Requires. that geologic reports be submitted to th~ State Geologist for open-file.

PROGRAM FOR ZONING AND EVALUATING FAULTS

Requirements of the Act

Section 2622 of the Alquist-Priolo Special Studies Zones Act (Appendix A) requires the State Geologist to'

I. "Delini:ate ... appropriately wide special s1udies zones to en· compass all potentially and recently active traces of 1he San Andreas, Calaveras., Hayward, and San Jacinto faults, and such other faults or segments thereor, as he di:ems sufficiently active and well-defined as to c:onstilute a potential hazard to s.1ructurcs from surface faulting or fault creep."

2. Compile maps of Special Studi~ Zones and submit su~h maps to affected cities, i::ounties, and state agencies for their review and comment. Following appropriate reviews, the Stale Geologi:st·must provide Official Maps to the affet:tcd cities, coun­ties, and state agencies..

3. Continually review new geologic and seismic data in order to revise the Special Studies Zones or delineate addi1ion::!!l z.ones.

These requiterncnts constitute the basis for the State Geolo­gist's rauh-zoning program and fo[' many of the policies. devised to implement the program.

Progrom for Zoning Foults

As required under the Act; the Stat~ Geologist initiated a program early in 1973 10 delinea1e Special Studies Zones to encompass potentially and recently active I races of the San An­drea$, Calave1a.s, Hayward, and San Jacin10 faults, and to com~ pile and distribute maps of these zones_ A project leam, headed by this writer, was established. within the Division to develop and conduct a program for delineation of the zones.

Initially, 175 maps of Special Studies Zones were delineated ro[' the four named faults. These zone maps. issued as Prelimi· nary Review Maps, were distributed for review by local and !>fate government i.igencles on December J 1. l 97 J. Folll)Wing pre­seribed 90-day review and 1e1Jis.ion periods, Official Maps were issued on July l. 1974. At that time, the Special Studies Zone~ became effective, and the affected cihcs and councies were re­quired to implement programs to regulllte development within the mapped zoni:s. A se~ond ~et of Official M.aps-81 maps. of new zones and live maps or revised zones~was issued on Janu­ary l, 1976, to delineate new and revised zones. Additional Official Maps of new and revised zones were issued in succeeding years, as summarized in Table 3.

All of the Special Studi~ Zones Maps issued prior to January I, 19781 were based almost solely on the mapping of others. Later maps are based extensively on interpretations or the: Fault Evaluation Program staff.

T()b/~ 3, Official Map.s ,,f Sp~t::ial Shldi~!f. ZtJn~.s i.s!f.u~a a:i cf January 1, 1985.

Da'• of /1$/J~ Now f? • .,,j$~d map:!f. m'1p:!

July 1, 1974 175 January 1, 1976 81 5 January 1, 1977 4 3 January I. 1978 1 July 26, 1978 2 Janu3.ry 1, 1979 4 7 January 1, 1980 21 9 January I. 1982 13 27 2 January 11 1983 18 12 January 1, 198.5 33 10

Totals 352 73 2

Steven Craig June 14, 1999 Page 34

As. of Januaty I. lQ8S, 352 Official Maps of Srecial S1udics Zone!i. have been b~u~d. Seventy-three of th~e rnaps have be(:n revi~ed since their initial h.sui:= and 1wo have been wilhdrawrL The mar~ are identified by quadt.angle map name and 1hc date of issue or tevisinn on the Index lo M<ip!i. ()fSpcl·ial Studies Zones

(Figure 4). The maps delincale regulatory .zones for !he faults identified ln Figure 1. Additional faults will be zoni::d in the fu1ure, and some zones will be revised. Thirly counties and 74 dlies are affected by the exis1ing Sreci.al .S1udies Zones. The!;e Juris.dictions are lis1ed in Table 4.

Tab/9 4. Cltie$ ond c1;111nties alfect~d by Special $fudi~$ Zont:~ as of Janvcry l, 798.5. *

Antioch Arcadia Arca.ta Bakersfield Banning Berkeley Beverly Hills Bishop Brea Carson Coach<ila CoUon Compton Concord Cotona Culver City Daly City Danville

CITIES ( '4)

Desert Hot Springs Dublin El Cerrito Foirfi<id Fremont Glendale Hiiyward Herne1 Hollister Huntington Beach Indio Inglewood La Habra Lake Elsinore Livermore Loma Linda Long Beach Los Angeles Mammoth Lakes Millbrae

Milpitas Monrovia Morgan Hill Oakland Pacifica Palmdale Polo Alto Pasadena Pleasanton Portola Valley Rancho Cucamonga Redlands Rialto Richmond San Bernardino San Bruno San Fernando San Jacinto San Jose San Juan Bautista San Leandro San Marino San Pablo San Ramon Santa Rosa Seal Beach Signal Hill South Pasadena South San Francisco Trinidad Union City Walnut Creek Willits Woodside Ventura {San

Buenaventura) Yorba Linda

COUNTIES i 30)

Alarn~da Alpine Butte Contra Costa Fresno Humboldt Imperial Inyo Kern Lake Lassen Los Angeles Marin Mendocino Mono Monterey Napa Orange Riverside San Benito San Bcmardino San Diego San Luis Obispo San Mateo Santa Clara Santa Cruz Solano Sonoma v~ntuta

Yolo

•To inquire obout lo1;1:1I go..,.ernm~nt polii;;i•1 cmd regulotion• or lo con1ult [obtail'I) t.cpies of 1pecifk. Spei;iQl Studie1 Zone1mops,1;1i;ldr•u tli111 Plonl'llng Oiri!!Clor i;if •!:l~li county o-r i;;ity. Some iul'i:t.dktiOn$ figv• r•pla.tt&d the SSZ bc1,mdgri•1i en lorge•Ji;;Qlll" parcel mops.

Definitions, Policies, Rationale

In order fOr the State Geologist 10 carry out his manda1e 10 establish reguhuory zones. certain terms identified in Seclloii 2622 of the Ael had to be defined and policies had to be devel­oped 10 provide a consis1ent and reasonable approach lO zoning. After the :ioning program WilS underway and the surface= fauh· tup1ure process wa!i ~tter understood, other terms were defined and some zoning policies were modified.

Fault and Fault Zone

A fa.ult is defined as a fracture or zone of closely associated fractures along which rocks on one side have been displa.ced with respcct to those on the other side. Most faults arc the result of repeated displacement which may have taken place suddenly and/or by slow creep. A f~u/t zone is a zone of related faul!S which commonly arc braided and subpa.rilllel, but m~y be branching and dlvetgc:nt. A fault zone has significant width

Steven Craig June 14. 1989 Page 35

(with tespi:ct to the scale at u.·hii::h the fauh is being considered, portrayed, or investigated), ranging frorn a. few feet to several miles._

Fault Trace

A (suit trace is the line formed by the inte-l'!><=Ction of a fault and the earth's surface:. It is the representation of a fault as depicted on a map, including maps of the special studies zones.

Activ~ fault

For the pui-p0ses of this Act, an 8(..'fivc fault is defined by the State Mining and Geology Board as one which has "had surface displacement within Hol0¢ene time (about the last 11.000 years)" (>«Appendix B, Section 3601). This definition does not, of cour.;c, mean that faults having no evidence for surface: displacement within Holocene time ate ncce:ss.arily inactive. A fault may be presumed to be inactive based on satisfactory geo­logic evidencei however, the e.vidence necessary to prove inactivi· ty som~limes is difficult to obtain and locally may not e>:.ist.

Potentially Active fault

Because the Alquist-Priolo Act requires the State Geologist to establish Special Studies Zones to encompass all .. potentially and recently ac1ive" 1races of the San Andreas, Calaveras, Hayward, and San Jacinto faults, additional definitions were needed (Sec· tion 2622)_ Faults were defined as pOtcntia.Jly activ~. and were ioned, if they showed evidence of surface displacement during Quatenlary time (last 2 million years, Figure 2). E7i.ccptions were made fo1 certain Quaternary (i.e., Pleistocene) faults that were presumed lo be inactive based on dil"¢¢t geologic evidence of inai::tivity during all of Holocene time or longer. The term ··recently active" was not defined, as it was considered to be covered by the ter-rn "p0tentially active,"

.

Suffici.,ntly Active and We/I-defined

A major objective of the Division's continuing fault zoning and evaluation program is to e:valu.ate the hundreds of remaining p0tentially active faults in California for zoning consideration. However, i1 be~:a.rne apparent as the program pl'ogre!jsed that there are so many potentially active (i.e., Quaternary) fauilf> in the S11:1te (Jennings. 1975) that i1 would be meaningless to zone all of them. In l~tc 1975, the S1a1c Geologisi made a policy decision to 2oni::= only those potentially active faults !hat have a tela1ivC'ly high poterHial for ground tupture. To facililnle 1his, the terms .. sufficiently active" and "well-def!ried," from Section 2622 of the Act, were defined for application in zoning faults other than the four named in the Ac1. These two tetm~ constitute lhe present criteria u.sed by the St.are Geologist in dete!'mining if a giv~n fault should be zoned under the Alquist·Priolo Ac;t.

Sufficiently activ~- A fault is deemed sufficiently active if there is evidence of Holocene sur'face displacement a.Jong one or more of its segments or branches_ Holocene surface displacement may be directly observable or inferred; it oeed not be p1esent every· where along a fault to qualify that fault for zoning.

Well·d~fincd. A fault is considered well-defined if its trace is clearly detectable by a trained geologis1 as a physical feature at or just below the ground surface. The fault may be identified by direct observation or by indirect methods (e.g., geomorphic evi­dence; Appendix C). The critical consideration is that the fault, or some part of it, can be located in the field with sufficient precision and confidence to indicate that the required site-specif· ie investigations. would meet with some success.

Determining if a fault is sufficiently active and well-defined is a matter of judgment. However, these definitions provide stand~ ard, workable guidelines for establishing Special Studies Zones under the Act. More precise meanings or these terms should develop as more is learned about the techniques of evaluating the hazard of surf~cc faulting .

Gl':OlOGIC AGE YEARS BEFORE

E'o Period Epoch

Histor:ic

Holocene

QUATERNARY '-' 0 Plel=itoc..,. "' 0 %

"' '-'

Pliocene ToRTIARY

pr•·Pliocene

pre~CENOZOIC time

;aeqinnino of oeolo~ic: time 1

PR ESE NT (Hlimalod I

2

11,000

2,000,000 -5,000,000 -

66,000,000 -,4,Goopco

}

FDult:1 oking whic;h mo¥emen1 Ila~ 0<:i:1,1rT•d during tlii$ int•rval ar• ct.fined (" Qf;liY• by Palki1U Dnd Crit1trig cif th11 Sta1e Mlnin!jl ond Geology Board.

F0i1,1lh d.finecl as pol-Mlliolly "'"'~for tM purpoM af l!tv~luotiQl't for pouiblit fOni;i•

tlan.

Steven Craig June 14. 1999 Page 36

The evaluarion of faults for 7.oning purpot.es is done with the n:alization that not all ~ctive fa1,1lts can be idi::ntified. Further· more, i:.ertaln faults considered to lx: :ictive at depth, because of known ~cismic activity, are so poorly di::fined at the surface that zoning is impractical. Although the Map eJC.planation (Figure 3) indii:: .. tes that "po1cntially active" (i.e., Qua1ernary) fault~ arc identified and zoned (with e~ccptions) on the Official Maps of Special StudiC'i Zortes., this. is. basicall~ true only for thos.e maps issued July I, 1974. and Janual"y t, 1976. Even so, all of the prh1cipal fault~ zoned in 1974 and 1976 were ai::ti.,.c during Holo­cene time, if not his1orically_ Beginning with the maps of January l, l977, all faults zoned meet lhe criteria of "sufficiently active and well~deflned."

Delineating the Special Studies Zones

Special Studies Zones arc deline.ated on U.S. Geological Sur­vey ropograpb.ic bas.e maps at a scale of 1;24,CQO ( 1 inch equals 2,000 feet). The 2one bound.arics are s1raigh1-li11e segments de· fined by turning poirns (Figure 3). Most or the turning points are intended to coincide with loc-atable featur'5 on the ground (e.g., bench marks, roads, .streams). Neither the turning points nor the connecting .tone boundaries have been sur\'ii:yed to "'~rify iheir mapped locarions.

L()t::.a.tions of SpeclalStud\es Zone boundar-\es are controlled by I he rt)Sition of fa1,1lt traces ~hown on the Official Maps of Special Studh~s Zones. With few ex.cl'plions, the faults shown on the 1974 and 1976 Sp<:cial Studies Zones maps were not tield-checked during 1he compilalion of these maps. However, all faults zoned since 1$nuary 1, 1977, have been field-che:cke:d ~o veriry that they do meet the criteria of sufficiently ac:tive and well .. defined.

Zone boundaries on early maps were positioned a.bout 660 feet (200 meters) away from the fault traces to accommodate impre­cise \oca1lons of the faults and possible existence of .active branches. The policy since 1977 is to position the: SSZ boundary about 500 t~c away from major .active: faults and About 200 to JOO feer away from well-defined, minor fault!;.. E.x.ceplions to this policy exis.t where faults are locally complex or where faults are nor V!:rtical.

Fault Evaluation Progrom

The Fault Evaluation Program was. initiated il'l early 1976 for the purp0se of evl\luating those "other faults" idtntified in the Aet as "s.ufficienrly active and well·defined" (see definition above) after it was riteogni:z:ed that e:ffectiv~ future zoning could nol rely solely 011 the limited fault dara of otheJ"$_ Justitication of this progT;;i.m is dise1,1ssed in more detail in Special Publication 47 of the CaHfornia Division of Mines and Geology (1976; also see Hart. 1978).

The program was originally scheduli:d over a ten-year period. The slate was divided into ten regions or work arc-as (Figure 1), with one region s.cheduled for evaluation each ye~r. However, 1he work in some regions has been extended ror various reasons (Hart and others, 1981, 1983, and 1984) and it is expected that the regional evalua1ion work will be completed in 1988. The fault evaluation work includes limit~d fi~ld mapping and the interpre­tation of aerial photographs, a.s well as the us.e of other geolo~ gists" work, A list of faulr.s 10 be evalualed in a target region is prepared and priorllies assigned. The list includes potentially active faults not yet zoned, as well as previously zoned faults or fa.ult-segments that may w11rrant a zone revision (change or deletion). Faults also are evalu.!lted in areas outside or scheduled regions, as 1he need arises (e.g., to map fault-rup1ure immediate­ly after an earthquake).

For each fault evaJ1,1atcd. a Fault Evaluation Report (FER) is prepared, :'iummarizing data on the location, rec:.ency of activ­ity, and .!:iense and magnitude of displacement. Each FER c:on­tains recommendations. for or against zoning. These in-house reports are filed .at the Division's Bay Al'ea Regional Office at 380 Civlc Drive:, Suite 100, Pleasant llill, where they are avail· able for reference:. Reference copies or the FER 's are filed in the Division's Los Angeles office_

Evaluations for the first six regions. ha,ve beii:n completed. Work in the 1984~1985 r~gion is underway, but it has been ex.tended s.i~ months to accommodate the evaluation of addition­al faults in other regions where new or revised zoning is needed. The result of the work done in the first sh: regions are summa­rized in open-file reports (Hart and others, 1977, 1978, 1979, 198t. 198J, and 1984). These reports arc available at a nominal cost from the Bay Area Region.a.I Office ln Plea....:;an~ Hill.

As a result of the fault evaluations made sirtce 1976. 96 new and 68 re.,.is.ed Special Studies Zones Maps have been issued and two maps. have been withdrawn (Table 3). The faulis zoned are c:onsidered 10 meet the: criteria of "sufficlen1ly acth·e ~nd well~ defined" (see Definitions above). Many other faults did not appear to meet the criteria and were not zoned. It is in1porrant to note that it is s.omettmesdifficult todi~tingu1sh between slight­ly active faulls and in~ctive ones, because the surface features formed as a Te:;u1t of minor, infrequent rupture ate easily obliterated by geologic proces.se.s (erosion, sedimentation, ma~s wasting) or the activities of m"n- Even large-scale fault·rupture" caQ be obscured in complex geologic terrancs o~ high-energy environments. Recent fault-rupture also is. difficuh to dete-ct where ii is distributed as. numerous. breaks or warps tn broad zones of deformation. As a consequence of these problems, it is not possible to lde:ntify and zone all acrive faults in Californh1.. For the mosr part, rupture on faults not identified as active is. expecled 10 be minor.

During the las' 10 years1 there have been 14 e.~rthqua.kes or earthquake sequences associated with surface faulting in various parts of California (lab\e 5). This ls an a\'erage of 1.4 fault­rupture events pet year. Most of the recent surface faulting has been relatively minor, either in terms of amount of displacement or length of surface rupture (Table 5). However, 30 cm (one root) or more di.splacemertt occurred during four events. in 10 years. Past records (incomplete) sugges.t that displacements of a meter (3 feet) or more occurs at least once every 15 to 20 years in Californla (Bonilla, \970-, Grantz. and Bartow, 1917). Many of the recent coseismic events occurred on faults that were: not yet zoned for special studies, a.ad some were on raults not consid­ered to be potentially active or not even mapped. Howe'l'ef, co.seismic rupture also occurred on faults within 1.he Special Studies Zones. In addition, a.seismic rautt-creep has occurred on many zoned faults in the last 10 years (see footnote, Table 5). Mos.t fa.ult cre:ep is tectonic (i.e., natural), although .'!Orne is induced by man (mainly by nuid withdrawal).

In addition to evaluating and i.oning faults, Program 5taff also perform other functions l'lecessary to 1he lmplementalion of the APSSZ Act. Regulations (Section 3602, Appendix B) require th.at cities and counties file geologic reports for "project" sitc:s in Special Studies Zones with the State Geologist. B~ the end or January t 98.:5~ 1761 site.~gcologic reports had been filed for public reference (available at the Division's Pleasartt Hill Office). An index map of these Teports was prepared to mak¢ others awa.re of thi$ resource (Wong, 1984). In order to improv~ the guality of site investigations and reports, guidelines were prepared in l 97S to assist others in evaluating faults. These guide\\nes have been slightly !'(:Vised and ~ppear as, Appendi.x C.

If a clty or county considers that a. gi::ologic iovestigation of a proposed "proj~t" is unnecessary, it may request a waiver from the State Geologist (Section 2()23, Appendix A). A Waiver

Steven Craig June 14. 1989 Page 37

Form detaillng the: procedures used is provided in Ap~ndi;t; D. Through January 1985, 69 Waiver Requests have been processed by Program staff.

Another important activity is to provide in(orrnation on the APSSZ Ac1. the Divis.ion's Fa.uh Evaluation and Zoning Pro· gram, and fault·rup!ure hazards to bo(h the public and private sectors. Program staff respond to hundreds or inquiries each )'ear from geologists, planners, building officials, di:velopers., rea.hors, financial ir1sri1utions, and othets.

Uses and Limitations of Special Studies Zones Maps

The Special S1udies Zones are delineated to define 1hose areas within which special studies are required prior to building struc· tu res for hum;;in occupancy. Traces of faults are shown on the maps mainly 10 justify the locations of :z.onc boundaries. These fault traces are ploued as accurately as the sources of data per­mit; yet the plots are not sufficiently accurate to be used as the basis for building set-back req1,1irements, and they should not be so used.

The fault informarion shown on the maps is not sufficienl to meet the requirement for special studies. Local govcrnmenral units mus1 require the developer to evaluate specific sites wtihin the special s1udics zones to de1ermine if a potential haz.a.rd from any fault, whether heretofore recognized or not, exists with re· gard to proposed strui:tures and their occupants.

The surface" fault ruptures associated with historic earthquake and creep evenlS are identified where known. However, no de~ gr~ of relative po1ential for future surface displacement or de· gree of haz:ard is implied for the faults shown. Surface ruptures resulting from the secondary effects or seismic shaking (e.g. 1

landsliding, dirTeren1ial settlemenl, liquefaction) are omitted from the map and do not serve as a basis for .z.oning.

Active fauhs may exist outside the Special Studies Zones on a.11y zone map. Therefore, fault investigations are rec:ommc:nded for critical and important developments proposed outside the Special S1udies Zones.

INDEX TO MAPS OF SPECIAL STUDIES ZONES

The following pages (Figures 4A 10 4H) indica1e the names and locations oft h1: official m.1'ps of special studies zoni=s dcline· ated by the Californi~ Division of Mines and Geology under 1h~ AlquiM-Priolo Special Studies Zor1e~ Act of 1972 (Appendix A). These index pages identify all OtT1cial Maps of Spc:c;ial Studie!". Z~)ne:;; released b)· 1hc Stale Geologist through January l, 1985. The official n1ap!> an: compiled on U.S. Geological Survey 7.5· minute 1opographic quadrangle maps al a scale of 1 inch equals 2,(XX) fee-( (Figure 3). Cities and cou111ies affected by 1hese maps are listed in Table 4.

Because S~cial S1udie~ Zones maps will be issued approxi­mately once a ~·ear to de!inci:ue re,·ised and additional zones, users of 1hi:sc maps. s.h11uld check wi1h the California Di\·is.ion of Mines a11d Geology for up-10-date information on neW and re­,·iscd Special S1udies Z(Jncs map~- A Change in zone~ als.o may affect differc:111 101,:al governments. This indC';i;. lo Official Maps of Spi:1,.·ial S1udlt:$ ZClnes (Figures 4A to 4H) will be revi:.ed in fulure years as new map~ are issued.

"fhe Special Studies Zones maps are available for pun.:has(" as indicated under Availability of Special S1udie:s Zones Map~. Also, 1hey may be consulted at any offic.:e of the California. Division of Mines and Geology and a1 the planning departm~ntfi of all cities and counties locally affected by Spe1,:ial Studies Zones (Tabi< 4).

Availability of Special Studies Zones Maps

Reproducible masters. from which copies of local Special Siudies Zones. maps (scale 1:24,000) c.an be made, h:;ivc ~en provided to eaeh of fhc cities and c.:ounties affecled by the z.onrs. Requesrn for copies of particular Special Studies Zones trta.p~ of local ari::as should be directrd to the Planning Dircc1or of rhe appropriate city or coun1y. Refer to the index to special s1udies zones maps for the quadrangle names of the rru1ps needed.

Arrangcmenrs also have been made with Blue Print Service Compariy, San Francisco, to provide blue line copies of the Special Studies Zones maps to those who cannot get lhi:m con~ veniently from the cities and coun(ies.

Blue Print Service Company 149 Second Street San Francisco, CA 94105 Telephone' (415) 495·8700

Each map must be ordered by quadrangle name as ~hown on the index. map. The cost of the maps is nominal, although there is a minimum charge; handling and C.O.D. charges are extra. These maps are not sold by the California Divi!i.ion of Min~ and Geology.

REFERENCES

!¢1'1illa, M.G .• 1970, Surloc1t fa1,11ti11Q and 'elo1itd 11ffecll ifl ;:,L. Wiegel, 11d1f¢r, Earth'

(lll<ik11 Engil't••ri!li: Prel'ttic:.-11011, Inc., Er1gl1fwood C:lilh. NJ, p. 47-74. Colifomio Di't'i'i~n of Min~1 ol'td Oeology, 19-76, .A.cti't'e fa1,1li mopping a11o' 11voluo1ion

pr<igram- 10-ytigr P'ogrom 1¢ implem1tl'll AIQ11i1t·Priolo Spt'ciol S.tudi11t Zone1 Act: Ci:ilifornia Oi~hi;.n of Min1H Cl!'ld Geology Si>rciol Public..:ition 47, 42 p,

Gral'ttl, A., and !orlQw, A., 1977, A.tliv11 lou11$ ¢1 Colifo,flii:ii U.S. Geolo.;i<OI Sul"'!'t'Y pomphl11t, 15p,

l-10,t, !.W., 1978. Zwiing for th11 hozard ol nirli:ic .. fault 'VPlllrt' in Colifo111l<i, ln111rno-1'1onal Conf•tlfl'IC1t on Mic1~~011..:i!ion, 2nd, Sori Fronciu:o, 1978, Proc.t1frding1 ..... 2, p. ti.3.5-646.

H1ul, E.W,, Bortugl't¢1 E:.J., and S.111ith, f.C., 1977, Summary 1.i.i:i<;irt-Foult Evol~t;ition PfogtO"rn, 1976 ei1•..:i (Wt'tll!'l't Tron1v11r111 R""Ou): Californi(I Divi1iill'I oi Mi11111 ond G•ology Op•t1 Fil..r R11po'I '17-8 :if, 13 p., :2 platu.

Hart, E.W., 9.ryonl, W.A., i;mJ Smith, T.C,, lV!IJ, Su11·11nary repo1t - Fault E•illudlil)f"

Pr091af!'I, 1981-1982 O•t'o (North11111 C...a11 Rong•1 '"Wion): C"lifi:;.mio Di•i1><Jn ¢/ Mine1 al'ld 011ology Oi:ien Fil11 ~1tpMt 83-10 SF, 16 p., l plalit

H1:1r1, E.W., l!ttygl"t, W.A., 0"11d .Smith, T.C:,, 198.oi, Sull'lmo:iry report - ~Ql!lt Evoluali¢n Prografl'I, 1983 o'.i.o (S.i111ra N1tvod.:i •efjlionl: Coli/omio Di~i1ion of i.l\ir,~1 al'!d G11oloo~ Op11n fil11 R•p<irt 84·5'1 S~, 2'- p., '1 pl.:itu.

H<;irl, E.W., !ryQnt, W.A .. .Smith, T.L, l!t11dr¢nion, T.L, 011d Smith l;).F>,, 1981, S.umm~ry r11po'I ~ ~gult E't'olui:ilion ProQ:,ilfl'I, 1979-1980 "*"O (1outhatl'I :So., Franci1co (!joy r11giol'I) 1 C<ilifomio Ol.-i1ion of Mi110 ond G.-,oloor Open Fil• R11por! gJ,3 S~. 23 p., 1 pli:it •.

Hi;ir1, E.W., S111ith, D.P., i:it1d Saul, R.!., 191V, Summery •!!port - F1;111lt Evoluotiet1 F'ro9ram, 1978 or110 (P11l'lin~11lor Rong.ti - Solton r,auoh •11gion): Col1l¢rnio Divi,iot1 ¢/ Min111 011d 011ology OP"n Fi!t' 11:.rpor! 79-10 SF, 17 p., 1 plat11.

Hort, E.W., Smith, 0.P., ond Smid\ T.C., 19-78, $11mmafy '•Port - Fault E.-Ql1,1Q1ion PrD!it•Om, 1977 .,,.,,.. (Lil! Al'IQ•llll'1 bo1in 1•gl61'1) 1 ColifDll'll~ Oivi1ion oi M1n-•1 ond 011.:ol(l(lr Open Filtr Reporl 78-!0 SF, 16 p,. 1 i:ola111.

J11r1fting~. C..W., 1975, ~oult milp ¢1 C.olilornio with l1:1catioM of volconoitl. !~<rrrnal

'P1in!i1, ond th1trll'l¢I wt'll1: Colilor11io Oivi1io11 ¢1 Mi'lt'I ond G110IC1g)'" Doto M<Jp No. I.

Wot1Q, P., 1984, Ind.,~ lo g11oloQIC r11porh l~t )i1111 ...,.ithin S~cial Stu~it'1 Zont-1: Colifornio Oi~i,i¢n i;if Mine1 a11~ 0t'olog)' Oi:i"n Fil~ Ritp1:1rt B•·Jl Sf.'] plot111. !'JOT6· R{ftr~nc~ 111":"~ 1(11·1)mpil~ fau11~ \>n ~ h1d1 1ht- Sr-eci.al S1114,~ z,ine~ irt !:ii"td ue l1•t11d on 111~ md1vidL1.al Off..:1.11 l.hpi.

Steven Craig June 14, 1989 Page 38

APPENDICES

Dat~ are presented herein to provide cily and couniy official:;, properly owners, developers, geologists, and others ,,,,ith specirk: information they rnay need 10 effectuate thi= Act in practice. Becavse the Acl must be implemented at the local governm~nt level, it is impet"~Uive that lhe local entities understand its various complex aspects.

ALQUIST-PRIOLO SPECIAL STUDIES ZONES ACT

Excerpts from California Public Resources Code

DIVISION I. ADMINISTRATION CHAPTER 2. DEPARTMENT OF CONSERVATION

Article 3. State Mining and Geology Board and the Di vision of Mines and Geology

660. There is in the department a State Mirting and Geology Board consisting of nine members appointed by the Governor.

673. The board shall also serve as a policy and appeals board for the purposes of Chapter 7 .5 ( eommeni::ing with Section 2621) of Division 2.

DIVISION 2. GEOLOGY. MINES AND MINING CHAPTER 7,,, SPECIAL STUDIES ZONES

2621. This chapter shall be known and may be cited as the Alquist·Priolo Special Studies Z<lnes Act.

2621.5. It is the .purpose or this chapter to provide for the adoption and administration of 1oning laws, ordinances, rules, and regulations by cities and counties in implementation of the gc:.nera.l plan that i$ in effect in any city or county. The Lt-gisla· ture declares that the provisions.of this chapter are intended to provide pOlicies :t.nd criteria to assist cities, counties, and state agencies in the exercise of their resp0nsibility to prohibit the 1ocation of developments and structures for human occupancy across the trace: of active faults as defined by this board.

This. chapter is applical)le to any project, as defined in Section 2621.6, upon issuance of the official special studies zones maps to affected local jurisdictions, but does not apply to any de1,1elop· ment or structure in existence priot to May 4, 1975_ The im­plementation of this chapter shall be pursuant to policies and criteria ~tablishcd and adopted by the State Mining and Geol­ogy Boord.

2621.6. (a) As used in this chapter, "proj.:<l" means: (I) Any subdivision of land which is subject to the Subdivi~

s.ion Map Act, Divis.ion 2 (commencing with Section 664 lO) of Title 7 of the Government Code, and which contemplates the eventual construction of structures for human oceupancy.

(2) Structures for human occupa.ncy, with 1he exception of: (A) Single-family wood framie dwellings \o be bu lit on p<!rcels

of land for which geologic ri:ports have been approved pursuant to the provisions of paragraph ( 1) of th\s subdivision.

(B) A single-family wood frame dwelling not e~ceeding two stories when such dwelling is 11ot part of a developmeni of four or more dwellings.

(b) For the purp0ses of this cha.pter1 a mobileliome, who~e body width exceeds eight feet shall l)e considered to ~ a single­family wood frame dwelling not exceeding (W(l stories.

2621.7. This chapter, except Section 2621.9 shall no1 apply w the conversion of an exisling .apartment cornpkx. in10 a <:ondo­minium. This ch.a.p1cr sha.I) apply 10 projects which are Joc.::-Hed within a delineated special s~udies z.ane.

2621.8. This chapter shall not apply to alterations or additions to any structure within a special studies zone the value of which does not e,.ceed 50 percent of the value of the Structure.

2621.9. A person who is acting as an agen1 for a selkr of re~l property which is located within a dcline.a1ed special studies zone, or the seller if he is acting without an a.gent, shall disclose to any prospec:tive purchaser the fact that the propeny is located within a. delineated special studies :i:one..

2622. In order to assist citi~ and counties in 1heir planning, zoning, a.rid building.regulation functions, 1he State Geologisl shall delineate, by December 3 l. 1973., appropri'ate\y wide spe­cial studies zones to encompass all potentially and recently active traces of the San Andr~'S. Calaveras, Hayward, a.nd San Ja.c:into Faults, and such other faults, or segments rhereof. as he deems sufficiently active. and we11~defined a.5 to constitute a potential ha.iard to structures from surface faulting OJ' fault creep. Such special stud'es z.ones shall ordinarily be one-qusner mile or less in width, C!Xcept in circumstances which may require the Siiue Geologist to designate a wider zone.

Pursuant to thi5 section, the Sra1c Geologist :!iohall compile rnaps. delineating the special studies zones and shall submit such maps to •II affected cities, counties, and state agcn<:ics, not later than December 31, 1973, for reviev.· and comment. Concerni:d jurisdictions and agencies shall submit all such comments to the State Mining and Geology Board for review and con.sideration within 90 days_ Within 90 days of such review. the State Geo lo~ gist shall provide copies of the official ma.ps to concerned state agencies and to each city or count)' having jurisdiction over lands lying within any .such zone.

Thi: State Gi:ologist .shall continually ti:view ni::w geologii:;: and seismic dat~ and sh~ll revise the speci~I studies zones or deline.a.1e addirional spi:cial studies zones whert warranted by new infor­mation. The State Gcologi.s.t shall su.bmit all revised. maps and

Steven Craig June 14. 1989 Page 39

additional maps to all atTe:~ttd c~ties, counties, and state agi:=ncies for their review and comment. Concerrted jurisdic;tions. and agencies shall submit all s.uch comments to the State Mining artd Ge.o!ogy Board for review and consideration within 90 days. Within 90 days of such review, the State Geologist shall provide: copies of the revised and additional official maps to concerned state agencies and 10 each city or county having jurisdiction over lands lying within any !'.UCh zone.

2623_ The approval of a project by a city or county shall be tn accordance with pol\cits and criteria established by the State Mining and Geolog)o board and the findings. of the State; Geolo­gist. In the dev~loprnen1 of such policies. and criteria, the State Mining and Geology Board shall seek the comment and advice of affected cities. counties, and state agen..::ies. Cities and cou:n.hes shall require, prior to the approval of a project, a geologic rep0rt defining and delineating any hazard of 5urface rault r'Upture. If the: city or county finds that no undue ha.urd of this kind exists, lhe geologic repon on such hazard may be waived 1 with approval of the State Geologist.

After a. report has been approved or a waiver granted, sub!;;e~ quent geologic reports shall not be required, provided tha.l new geologic data warratHing further investigations is not recorded.

2624. Nothing in this chapter is intended to ptevcnt cities. and counties from establishing p0licies and criieria which are stricter than those established by this chapter or by the State Mining and Geology Board, nor from iniposing and collecting f~ in addi· tion to those required under this chapter.

2625. (a) Each applicant for approval of a project may be charged a reasonable fee by the city or county having jurisdiction over the project

(b) Such fees !'.hall be set in an amount sufficient to meet, but not to exceed, the coses to lhe city or county of adminls.tering arid complying with the provisions of this chapter.

(c) The geologic report required hy Section 262J shall be in sufficient detail to meet the criteria and policies established by the State Mining and Geology Board for individual parcels of land.

2630. Irt carrying out the provisions of this chapter, the State Geologist and the board shall b(: advised by the Seismic Safety Commission.

SIGNED INTO LAW DECEMBER 22, 1972; AMENDED SEPTEMBER 26, 1974, MAY 4, 1975, SEPTEMBER 28, 1975, SEPTEMBER 22, 1976 AND SEPTEM!3ER 27, 1979.

POLICIES AND CRITERIA OF THE STATE MINING AND GEOLOGY BOARD

With Reference to the Alquist-Priolo Speo;iol Studies Zones Act

(Excerpts from the Colifornia Administrative Code, Title 14, Oivi>ion 2, Chopter 8, Subohaptet 1, Article 3)

3000. Purpose. It ·is the purpose of this subchapter to st:t fonh the policies and

criteria of the State Mining and Geology Board, hc:reinaftc:r rc:ferred to as the "Board," governing the e;i1;.ercise of city, county, and state agency r~ponsibilities to prohibit the location of deve· lopment.s and structures for human O(:tupancy across the traci: of active faults in accordance with the provisions of Public Re~ sources. Code Sectio11 262.1 ef seq. (Alquist-Priolo Special Stud­ies Zones Act)_ The policies and criteria set forth herein shall be limited to potential hazards resulting from surface faulting or fault ~reep within special studies ionics delineated on maps offi· oially ;,.ued by the Stale Oeologi>t. NOTE: Authority cited: Section 2621 . .5. Public Resources Code. Reference: Sections 2621 • 2630, Public Resources Code. 3601. Dc:.finitions.

The following deflnitio11.s as used within the A«:.t and herein shall apply:

(a) An "active fauh'" is a fault that has had surface displace­ment wi1hin Holocene: time (about the last t t,000 years), henc~ c:onstituting a potential hazard to structures that mighl be local· ed. across it.

(b) A "fault trace:" is that Hne formed by the int~rsection or a fault and !he canh's. surface, and is the ri::present$tion of a fault a.s depieted on a map, includirig maps or special studies zones.

(c) A "lead agency•• is the city or county with the authority to approve ptojc:cts.

(d) 4'Spccial studies zones'' are areas delineated by the State Geologist, pursuant to !he Alquist-Priolo Special Studies Zones. Act (Public Resources Code Se<tion 2621 et seq.) and t11is sub­chapter, which e.n'Compas.s the traces of active faults.

( e) A "structure for human occupancyj-1· is .any structure used or intended. for supporting or sheltering any U$C: or occupancy, which is t"-pected to have a human occupancy rate of more than 2,0C>O pet"$0n·hours per year.

(f) "Story" is that portion of a building included between the upper surface of any noor and the upper surfa.ee of the noor neJ;t above, execpt that the topmost story shaU be that portion of a building included between the: upper surface of the topmost floor and the: ceiling ot roof above. For the purpose of the Act and this subcha.pter, the number of s.tories tn a building is equal to the number of disiinct noor levels, providc:d that any le\'els that differ from each other by less than two feet shaJI be considered a.S one distinct levet

NOTE' Authorily cited' Section 2621.5, Public Resources Code. Reference: Sections 2621 - 26301 Public Resources Code.

Steven Craig June 14, 1989 Page 40

3602. Review of Preliminary Maps. (a) The Board shall provide- an opportunity for receipt of

public comments and recommendations during the ninety (90) diy period provided by Public Resources Code Section 2622. which shall include at least one public meeting schi:duled for that purpose.

(b) Following the end of the 90-day review period, the Board shall fotward its comments and tecommendations, with support· ing data received, 10 the SnHe Geologist for consideration prior to his officially issuing the maps. NOTE: Authority cited; Sec­tion 2621.!i, Public Resources Code. Reference: Section 2622., Public Resources Code.

3603. Specific Criteria. The following specific criteria shall apply within special stud·

ies zones and shall be used by affected lead agencies in complying with the provisions of the acl:

(a) No sh'lJcture (ot human OCC\lpzncy, identified as. a project under Section 2621.6 of the Act, shall be permiUed ID be placed across the trace of an active fault. Funhermore, as the area within fifty (SO) feet of such active faults shall be pres:umed to be underlain by active branches of that fault unless proven olhcr· wise by an appropriate geologic investigation aod report pre· pared as specified 'n Section 3603-(d) of this subchapter, no such structur~ shall be permitted. in this area.

{.b) Affected lead agencies, upon receipt or official $pecial studies zones maps, shall provide for disclosure of delineated special studies zone~ to the public. Such disclosutc may be by teference in genf:ral plans, specific plans. property maps, or other appropriate ~ocs.l maps.

(c) No ch~nge in us~ or character of occupancy, which rcsuhs in the conversion of a building or stru<::~urc from one nol used for human occupancy to one !hat is so used, shall be pernii11cd unless the building or structure complies with the provisiorls of the: Act.

(d) Application for a development permit for any project within a deliue.a1ed special studies tone shall be accon1pan1ed by a geologic report prepared by a geologist n::gistered in the Sta.le of California, which is direc1ed to the problern of potential sur­face. fault di$placement through the project site, unless s~ic;h report is waived pursuant io Section 2623 of the A~t- The re­quired report shall be based on a geologic inveshgatio11 d~~igned to identify the location, recency, and na1ure offaulling thar may have affi:cted the projec( site in the pa~t and may affect 1he project site in the fulur'°. The report may be combined "''ith other geologk:a.I or geotecbnical reporis.

(e) A geologist regislcred in the State of California, within or retained by each lead agency, shall eYaluale the geologic report:; required herein and adYise the lead agi:ncy.

(I) One (I) copy of all •uch geologic ceports shall be filed with 1he State Geologist by 1he lead agency wi1hin thirty (30) days following the report's .acccp1ance. The State Geologist shall place such repons oo open tile.

NOTE! Authority cited: Section 2621.S, Public Resources Code. Reference• Sections 262L5, 2622, 2623, and 2625(c). Public Resources Code.

ADOPTED NOVEMBER 23, 1973; REVISED JULY 1, 1974, AND JUNE 26, 1975. CODIFIED IN CALIFORNIA ADMINISTRATIVE CODE JANUARY 31. 1979;

REVISED OCTOBER 18, 1984 (EFFECTIVE 30 DAYS THEREAITER).

•

•

•

TEUWHONE 17141 7'J4-67CMI

CLOPINE GEOLOGICAL SERVICES,

GEOLOGICAL AND AND EVALUATIONS 13(193 IJURNS LANE

TITLE:

PREPARED BY:

PREPARED FOR:

DATE:

R1':DLANDS, 1:,\1,lf'ORNIA

RIVERSIDE COUNTY 92373

Pl.ANNING DEPARTMENT ADDENDUM TO GEOLOGIC/SEISMIC REPORT FOR 20 ACRE (~} PARCEL IN THE NORTHEAST QUARTER OF THE NORTHWEST QUARTER, SECTION 7, TOWNSHIP 3 SOUTH, RANGE 2 EAST, S_B.B. & M., CABAZON AREA, RIVERSIDE COUNTY, CALIFORNIA

Mr. Gordon A. Clopine President, Clopine Geological Services, Inc. Registered Geologist No. 511, State of CA.

Mr. Steven A. Kupferman Engineering Geologist Riverside County Planning Department 4080 Lemon Street, 9th Floor Riverside, CA. 92501

AUGUST 10, 1990

REGARDING: RIVERSIDE COUNTY GEOLOGIC REPORT NO. 741, AND YOUR LETTER TO CLOPINE GEOLOGICAL SERVICES, INC., DATED JULY 30, 1990.

Dear Mr. Kupferman:

In response to your letter referenced above, please accept the following information and/or clarification, which is provided to you at your request.

Thank you for our telephone conversation concerning this matter that took place on August 8, 1990_

As you are aware, four topics were listed in your'letter of July 30, 1990. Each of the four topics will be addressed, in the order that you listed them_

Please consider all of the information contained in this addendum report to be supplem<>ntal to our forty page geologic:./seismic report referenced above, dated June 14, 1989_

Page 1 of 6

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CLOPl'll'. Gt;ULOGICAL SF;KYU.:ES, l'\L (;~))L,U(;l(;,\I. AM} F.:"o:"\l}l(~ML"iTAI. REJ'OF(Th MV 1::\/4.J.l)ATIO,rtt:>

Aodenq,um Report for .~ount.Y Geologic Report No, 7'•1 Aqgust 10, 1990 Pag(;':____g_

TOP}:_C ONE: DESCRIPTIQN OF fl\ULT ZONE IN GREAT!i:.~ DE_TAIL

On pages 2, 3, and 4 of this addendum report please find trench logs for Trenches 1-A, 1-B, and 1-C. The fault is further described, with attitudes of the fault plane indicated.

'.fRENCH 1-A

~ D/STAN~~ ~Ar1 /Vol2·nf£/l\<!fr ~.D o~ 7~<0A/CI>(

So' / 55' €.o' ~s· 70' '-.7.s"

NOTE::

oN'L )" Ao po/i!rtolll ~ TKEAIU/ t -A s.t-' o...,,.; 1:1 &Rt,

5' FO!i!. caMPu::T~ TREfi/df I-A,, SE'€ f'· 2-6 OF ouR i<,€pof2T 10' OF :TUA/€"

l'-6/7~?.

SOIJTH 28" wEsr-

..

1",,,_5'

Fault is described to be right-lateral strike-slip and reverse dip-slip (shallow thrust) in character. (An Q.l:Jliqlle slip fault). Structural features are variable along the strike of the fault. In Trench 1-A the shallow thrust nature of the fault is fairly well developed, modified by strike-slip movement. In Trench 1-B and 1-C the strike-slip nature of the fault is more prominent, with only hints at the compressive reverse component of motion. It is my judgement that the loose and unconsolidated nature of the sediments on the hanging wall (upper plate, northeast side as viewed in the trench} have allowed this variation in response to the compressive and shear forces which have been applied to the sediments during past tectonic events.

Strike of the fault across the trench as indicated (N 39°W)_ Reverse components of dip as indicated (10°to 12° }. Strike-slip component of relative motion as indicated (A -· away and T = tow<irdl. in poorly defined disturbed zone approximately 13 feet wide. Cobbles in zone above ~ at 65' from north end of trench appear rotated. Other details of fault movement not preserved in the unconsolidated phenoclas:tic sediments.

CLOl'INF. f;F,()LOGl<.:AL SFJ{Vl<.:ES. I\G. G•:<>lfll".l(:"-1. A.NU t::"li.1no:··iMl:;! .. TAL Hl::ronTI-i "'""U t;\'ALl:ATif)f'lj'.'j

• Addendum __ fteporJ for County Geologic Report No. 74.J, August 1 Q .____1_fil!Q

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Page '.,'l.

This log duplicated from Page 27 No. 741, a Geologic/Seismic Report June 14, 1989.

of Riverside County Geologic Report by Clopine Geological Services dated

Fault as described on page 2 of this addendum report. Major component of relative motion strike-slip in character, in irregular zone approximately 2 1/2' wide, with dip essentially vertical. Minor compressive reverse fault movement suggestive, with fault plane at 45• dip as indicated. #£

Strike of fault across trench North 35~ West, indicates northeast side of fault moving awav from southeast. I indicates southwest side of fault observer, to the northwest .

0

5

!i' /Cf

So1rrt1'i+o• WE'ST

,, 5' I ~

NO ~'L.

.w

as indicated. 6 observer, to the

moving toward the

s'

10'

o;t,OPL'"E GF1)L0GKAL SF.I< VICES. INC Gt:Ol .. O(.ICl\L A.'-,U t:,"\lROl'ri"\tl~TAL Hl:::J"ORT."i 4.NU l::\"AU.'A110l'tti

• Add~ndum _l.1~port for County Geologic Report No. 741 August lo __ , __ 199.Q

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TRENC" ___ J-C

This log is duplicated from page 27 of Riverside County Geologic Report No. 741, a Geologic/Seismic Report by Clopine Geological Services dated June 14, 1989.

Fault as described on page 2 of this addendum report. Major component of relative motion strike-slip in character, in an irregular zone approximately 4' wide, with dip essentially vertical. Less obvious compressive reverse fault movement also present, with dip of fault plane 359 to the northeast, as indicated.

Strike of fault across trench North 46° West, indicates northeast side of fault moving away from southeast_ T indicates southwest side of fault observer, to the northwest .

0

5'

as indicated. ~

observer, to the moving towa.LQ the

s-o'

.. I

~ f-{o..,,c£AIE ,,._ LLU VI(./.!"'\

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CLOJ'L"\F: GF.01 .OGICAL ~F:R\1CES. INC. GF.OI.OGll:.U, ANU Ei•i\lno···iMF.''IT..U. Hhl"OHTS A\l• l?t'ALL',\TION~

AddendUll! Repqrt for CountY .. Geologif; Report No_ 741 August 10, 1990 Page 5 of .6

TOPIG TWO, VERTICAL EXAGGERAI!ON OF TRENCH LOGS

Critical portions of the trench logs (Trenches 1-A, 1-B, drafted with no vertical exaggeration in this addendum trench log for Trench 1-A was originally drafted at 2x; Trenches 1-B and 1-C were drafted in our original report 1989 with no vertical exaggeration.

and 1-cJ report_ the logs of June

are The for 14,

It is agreed that all future trench logs will be submitted with no vertical exaggeration.

TOPIC THREE: SOU.RCE OF AERIAL .. PHOTOGRAPHS. UTILIZED

The three aerial photographs identified in our report of June 11•, 1989, as described as item (11), page 12, were obtained from Mr. Charles Price, Certified Engineering Geologist No. 183, of Yucca Valley California, telephone (619) 365-5447. Mr_ Price informs me that the photographs are available for your inspection, upon request.

TOPIC FOUR, LEGEND FOR MAP 1

Page 6 of this 6 page addendum report is a copy of our Map 1 reproduced unchanged from our report of June 14, 1989_ At your request, additional fault information from the State Alquist-Priolo Map is now included as a legend.

Six copies of our addendum report response to your letter are provided to your office, as requested.

Corporate Off ice and Residence: 13093 Burns Redlands, CA. 92373 (714) 794-6700

Lane

Respectfully submitted,

Gordon A. Clopine President, Clopine Geological

services, Inc_ · Registered Geologist No. 511 State of CA.

C.P.G. No. 6125, A.I.P.G.

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~ ALQUIST-PRIOLO SPECIAL STUDIES ZONE BOUNDARY

0 NG 0 .~

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Map 1. Location of Subject Property, and Alquist-Priolo Special Studies Zone boundaries. San Gorgonio Pass fault as shown on State Map (1974) approximately located_ This map a portion of the Cabazon Quadrangle, U.S.G.S., 1956, photorevised 1972, scale 1,24,000. North to top of page as indicated.

l:LUl'L' E GEULOGIC . .\J. ';EK \'ICES. I ~C. C.EJJLOGIC.U. ·'l"lit.l f:'\l 1 H f)'i,""\1J.:"iiT .\L IU:]--'(ffi~ A "Ill E,·.u.t:A 110\S

Addendum Report for County Geologic Report No_ 741 August 10. 1990 Page 6 of 6

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MAP EXPLANATION

Potenll 1lly Active Feull1

Faults considered to have been active during Quaternary time; solid line where accurately located, long dash where approximately located, short dash where inferred, dotted where concealed; query (? J indicates additional uncertainty. Evidence ol historic offset indicated by year of earthquake­assoc i ated event or C for displacement caused by creep or possible creep.

Aerial photo lineaments (not field checked); baS!'!d on youthful geomorphic and other features believed to be the resu Its of Quaternary faulting.

Special Studie1 Zone Boundaries

These are delineated as s!raig ht-line segments th at connect consecutively numbered turning points so as to define one or more special studies zone segments.

--------0 Seaward proiection ol zone bcundary.

IMPORTANT - PLEASE NOTE I

1) This map may not show all potentially active faults. either within the special studies zones or outside their boundaries.

2) Faults shown are the basis for establishing the boundaries of the special studies zones.

3) The identification of these po1entially active !au Its and the location of such lault traces are based on the best available data. Traces have been drawn as accurately as possible at this map scale, how ever, the quality of data used is highly varied. The fau Us shown have not been field checked during this map compilation.

4) Fault information on this map is not sufficient to serve as a sub­stitute for i nformatign developed by the special studies th at may be required under Chapter 7.5. Division 2, SectioJI 2623 o! the Califor­nia Public Resources Code.