Earthquakes and Floods

Earthquakes and Flooding DataPrepared by:Rockwell Land CorporationDesign & Planning Team

Earthquake Shaking of the Earth caused by a sudden movement of rock beneath its surface.

Epicenter That point on the Earth's surface directly above the hypocenter of an earthquake.

Fault A break in the Earth along which movement occurs. Sudden movement along a fault produces earthquakes.

Intensity A measure of severity of shaking at a particular site. It is usually estimated from descriptions of damage to buildings and terrain. The intensity is often greatest near the earthquake epicenter. Today, the Modified Mercalli Scale is commonly used to rank the intensity from I to XII according to the kind and amount of damage produced. Magnitude A quantity characteristic of the total energy released by an earthquake, as contrasted with intensity, which describes its effects at a particular place. A number of earthquake magnitude scales exist, including local (or Richter) magnitude, body wave magnitude, surface wave magnitude, moment magnitude, and coda magnitude. As a general rule, an increase of one magnitude unit corresponds to ten times greater ground motion, an increase of two magnitude units corresponds to 100 times greater ground motion, and so on in a logarithmic series.

Richter Scale Also known as the local magnitude (ML) scale, assigns a single number to quantify the amount of seismic energy released by an earthquake

Definition of Terms

Flooding Is an overflow or accumulation of an expanse of water that submerges land. In the sense of "flowing water", the word may also be applied to the inflow of the tide.

Statistical Hydrology or Flood Study Analyzes estimate future hydrologic phenomena, assuming the characteristics of the processes remain unchanged.

Hydrology Is the study of the movement, distribution, and quality of water throughout Earth, and thus addresses both the hydrologic cycle and water resources.

Above Mean Sea Level (AMSL) Refers to the elevation (on the ground) or altitude (in the air) of any object, relative to the average sea level datum. The 0.00 mean sea level is referred from the Manila Bay level.Return Period Also known as a recurrence interval is an estimate of the interval of time between events like an earthquake, flood or river discharge flow of a certain intensity or size. Can also be expressed as cycle.Tsunami A tsunami is a series of very long wavelength ocean waves caused by the sudden displacement of water by earthquakes, landslides, or submarine slumps. Ordinarily, tsunamis are produced only by earthquakes exceeding magnitude 7.5. In the open ocean, tsunami waves travel at speeds of 600-800 kilometers per hour, but their wave heights are usually only a few centimeters. As they approach shallow water near a coast, tsunami waves travel more slowly, but their wave heights may increase to many meters, and thus they can become very destructive.Definition of Terms

Wind Tunnel Test Is a scaled test to provide the necessary design pressure measurements for use in the dynamic analysis of the structure. It is used to determine the appropriate faade materials (e.g. thickness of glass)Acoustics Is the interdisciplinary science that deals with sounds. It determines how much sound passes through different materials and what to use for rooms that require a specific loudness or quietness expressed in Db or decibels.Marikina Fault or West Valley Fault System That earthquake prone belt on which we, Metro Manila lurkers, sit on. The fault extends from San Mateo, Rizal all the way down to Taguig down south, carrying with it the weight of these cities: Marikina, Pasig, Makati, Paranaque and Taguig. Soil Test Is the analysis of a soil sample to determine nutrient content, composition and other characteristics. It determines the type of structural foundation to use and how deep it should beDefinition of Terms

Earthquakes

Magnitude 8 Earthquake Locations Map

Earthquake Fatalities Map

MagnitudeRegionDate19.5Chile1960-05-2229.2Prince William Sound, Alaska1964-03-2839.1West Coast, Northern Sumatra2004-12-2649.0Kamchatka1952-11-0449.0East Coast of Honshu, Japan2011-03-1158.8Offshore Maule, Chile2010-02-2768.8Off the Coast of Ecuador 1906-01-3178.7Rat Islands, Alaska1965-02-0488.6Northern Sumatra, Indonesia2005-03-2898.6Assam, Tibet1950-08-15108.6Andreanof Islands, Alaska1957-03-09118.5Southern Sumatra, Indonesia2007-09-12128.5Banda Sea, Indonesia1938-02-01138.5Kamchatka1923-02-03148.5Chile-Argentina Border1922-11-11158.5Kuril Islands1963-10-13

Most Destructive Earthquakes in the WorldSource: USGS.gov

MagnitudeRegionDate17.9Luzon1990-07-1627.9Moro Gulf1976-08-1737.3Casiguran1968-08-0247.1Panay1990-06-1447.1Mindoro1994-11-1557.0Ragay Gulf1973-03-1766.8Bohol1990-02-0876.8Palimbang2002-03-0686.5Laoag1983-08-1796.2Masbate2003-02-15105.6Bohol1996-05-27115.1Bayugan1999-06-07

Destructive Earthquakes in the PhilippinesSource: USGS.gov

Mercalli Earthquake Intensity ScaleSource: USGS.govI. InstrumentalGenerally not felt by people unless in favorable conditions.II. WeakFelt only by a few people at best, especially on the upper floors of buildings. Delicately suspended objects may swing.III. SlightFelt quite noticeably by people indoors, especially on the upper floors of buildings. Many do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibration similar to the passing of a truck. Duration estimated.IV. ModerateFelt indoors by many people, outdoors by few people during the day. At night, some awaken. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rock noticeably. Dishes and windows rattle alarmingly.V. Rather StrongFelt outside by most, may not be felt by some outside in non-favorable conditions. Dishes and windows may break and large bells will ring. Vibrations like large train passing close to house.VI. StrongFelt by all; many frightened and run outdoors, walk unsteadily. Windows, dishes, glassware broken; books fall off shelves; some heavy furniture moved or overturned; a few instances of fallen plaster. Damage slight.VII. Very StrongDifficult to stand; furniture broken; damage negligible in building of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken. Noticed by people driving motor cars.VIII. DestructiveDamage slight in specially designed structures; considerable in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture moved.IX. ViolentGeneral panic; damage considerable in specially designed structures, well designed frame structures thrown out of plumb. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations.X. IntenseSome well built wooden structures destroyed; most masonry and frame structures destroyed with foundation. Rails bent.XI. ExtremeFew, if any masonry structures remain standing. Bridges destroyed. Rails bent greatly.XII. CataclysmicTotal destruction - Everything is destroyed. Lines of sight and level distorted. Objects thrown into the air. The ground moves in waves or ripples. Large amounts of rock move position. Landscape altered, or leveled by several meters. In some cases, even the routes of rivers are changed.

Mercalli (Intensity) vs. Richter Scale (Magnitude)Source: USGS.govRichter MagnitudeTypical MaximumModified Mercalli Intensity1.0 - 3.0I3.0 - 3.9II - III4.0 - 4.9IV - V5.0 - 5.9VI - VII6.0 - 6.9VII - IX7.0+VIII or higher

Flooding

Philippine Flooding: Historical DataMajor FloodTyphoonCauses of FloodNo. of Affected FamiliesEstimated Damage (in Millions)1986*SisangO/B/I--1993GloringO/B/I2,754-1994KatringF/O/B/I13,91922.81995RosingO/B/I109,25471.41997Ibiang & MilingO/B/I78,9536.62000 MayBiringO/B/I30,408-2000 JulyDitang & EdenO/B/I--2000 NovemberSeniangO/B/I--2009 SeptemberOndoyF/O/B/IF-Flash Flood / O-Overflow / B-Bank Erosion / I-Inland Flooding*Flood Level rose to +4.00 amsl at Lower Marikina River

Source: PAGASA

Reference Grading Plan & Flooding Heights

+2.65 Lowest Point+3.80+3.91+3.95+4.20+4.40+4.25+5.30+3.57+3.36+3.46+3.48+6.50+6.81+6.38+6.16+7.33+6.58+5.66+16.60+13.97+8.25+7.22+5.98+19.55+6.93+7.54+9.09+12.40+8.60+7.95+10.20+9.00+8.45+7.60+5.65+7.70+6.24

+11.15+11.20+7.90+7.75

Pasig River Level +2.18

+6.46

+6.45Data Source: Rockwell Center as-Built Survey by Gildo Jimenez dated 08 August 2006Elevation Mark locations are for reference purposes only not to be construed as exact.

+8.45

+3.95Tower GF Interior ElevationStreet ElevationLEGEND:*All elevation points are based on above mean sea level datum

Typhoon Ondoy Visual Flood Level Mark :Ankle High(+/-0.15m-0.20m)

Knee High(+/-0.40m-0.5m)

Waist High(+/-1.00m)

Chest High(+/-1.16m-1.20m)

JP Rizal corner Waterfront Drive

0.30 m highTyphoon Ondoy, September 26, 2009

Estrella in Front of Joya

0.35 m high

Typhoon Ondoy, September 26, 2009

Estrella in Front of Manansala

0.25 m high

Typhoon Ondoy, September 26, 2009

Estrella corner Rockwell Drive

0.15 m high

Typhoon Ondoy, September 26, 2009

C-5 Reference Grading Plan & Flood Heights

+4.46+5.16Lower Marikina River Level +2.18Data Source: Google Ondoy Flooding Map, 2009Elevation Mark locations are for reference purposes only not to be construed as exact.

+0.00

+0.00Tower GF Interior ElevationStreet ElevationLEGEND:*All elevation points are based on above mean sea level datum

Typhoon Ondoy Visual Flood Level Mark :Ankle High(+/-0.15m-0.20m)

Knee High(+/-0.40m-0.5m)

Waist High(+/-1.00m)

Chest High(+/-1.16m-1.20m)

+7.66

Geo-Hazard Maps

5 KM Radius Map from Rockwell CenterEstate Management Team , June 2010, Source: Google EarthROCKWELL CENTER

NEAST: Bgy. Ugong, Pasig City SOUTH: Sitio Masigasig, Taguig CityWEST: Bgy. San Isidro, Pasay City NORTH: San Juan CityTHE GROVE

E D S AC - 5SOUTH SUPER HIGHWAYROXAS BLVD.NAIA

Manila BayLaguna LakeThe FortAYALA AVE.BUENDIA AVE.PASIG RIVERSM MOACAINTATAYTAYMANILAMANDALUYONGPASIGRBC

Q.C.

Landslide Prone Areas MapEarthquake Risk Zonation MapFlood Prone MapMetro Manila Geo-Hazard Maps

Source: Mines & Geo-Sciences Bureau

Earthquake Risk Zonation Map

GR

GRRRBCSource: Mines & Geo-Sciences Bureau

Flood Prone Area MapGR

GRRBCRBCSource: Mines & Geo-Sciences Bureau

Liquefaction Hazards Map

Philippine Faults and Trenches Map

Valley Fault System Maps

Valley Fault System Maps

Valley Fault System Maps

Valley Fault System Maps

Valley Fault System Maps

Valley Fault System Maps

Valley Fault System Maps

Valley Fault System Maps

Valley Fault System Maps

Earthquake Design ConsiderationsAs Explained by Engr. Wilson Sy of Sy2 (From a letter to Rockwell, dated 28 May 2008)We will hereunder try to explain seismic design in a layman's term as much as we can, as per your earlier request. We would like to offer initially a few items that need to be clarified and are enumerated hereunder:Earthquake forces are based on magnitude. Magnitude is the amount of force that one particular earthquake generates. It can be the magnitude at the focal point or the magnitude at the earth's surface directly vertically up the focal point, which is called the epicenter. The epicenter therefore, lies on the earths surface. Evidently the magnitude at the epicenter is lower depending on the depth of the focal point of the earthquakes origin. As additional information, the amount of force that an atomic bomb will generate is also based on magnitude.Intensity is a subjective scale; it is based on the amount of damage that a particular earthquake will generate on the surrounding buildings. It is never a measure of the strength of the earthquake, but rather a measure of the amount of destruction that it generated on a particular location.The Richter scale was formulated in 1935, and is not a very accurate way of measuring earthquake magnitude beyond magnitude 7. The new method of determining the energy released by an earthquake is called Moment magnitude. it is somehow similar to the Richter scale from magnitudes 1 to 7, but is more accurate in higher magnitudes. More commonly used nowadays, even by the USGS is the Moment Magnitude Scale. Most Earthquake scales which include the Richter and the Moment Magnitude scales are based on a logarithmic scale and not a linear scale. This means that magnitude 6 is ten (10) times more powerful than magnitude 5, whereas magnitude 7 is ten (10) times more powerful than magnitude 6; therefore, magnitude 7 is one hundred (100) times more than magnitude 5.Additional factors that can affect earthquake design are proximity to a known active fault system, the known or expected activity rate of the known fault zone in terms of slippage per year, the kind or type of soil at the intended building site, the duration of the earthquake, and the depth of occurrence of the earthquake, or the depth of its focal point from the surface.We normally design buildings in conformance with the provisions of the National Structural Code of the Philippines (NSCP), 2001 edition and the Uniform Building Code (UBC) 2004 edition, which is used in the West Coast such as California, in the U.S.A. We have also used as Additional Codes of Reference, the American Concrete Institute Manual of Concrete Practice (ACI, 318-04 M) and the American Institute of Steel Construction (AISC, 9th Edition).Just like Japan and California, most of the Philippines is located under Seismic Zone 4 (except Palawan which is located under Zone 2). This is in accordance with the above-mentioned Structural Codes. Zone 4 is the zone with the most severe and most damaging seismic activity. There are specific and a wide range of code provisions that needs to be strictly considered in the design of structures falling under this special seismic zone. A dedicated chapter in the code is specified for this purpose. All of the applicable provisions of the Uniform Building Code (UBC) and the American Concrete Institute (ACI), including those of the local code, (NSCP), are all strictly considered in the Structural Design of the buildings we are designing.The UBC and the NSCP further require that buildings under Seismic Zone 4 be designed for computed equivalent static forces, as well as dynamic-induced loading.

Earthquake Design ConsiderationsAs Explained by Engr. Wilson Sy of Sy2 (From a letter to Rockwell, dated 28 May 2008)The dynamic analysis of structures makes use of the code prescribed normalized response spectra as the basis for the simulated earthquake ground movements. This spectrum is an envelope diagram of the more known and most destructive earthquakes in the past, wherein the historic data is available, and it includes among others: the El Centro Earthquake, the Mexico Earthquake, the Kobe earthquake, the Taiwan Jiji earthquake and the Los Angeles Northridge Earthquake, among others. The codes further stipulate that the resulting dynamic analysis base shear be scaled up to the equivalent static base shear as an added factor of safety in the design process.In the dynamic analysis of the structure, which is being performed diligently for most of the structures that we are designing, most buildings are modeled as three-dimensional space frames considering all of the properties of every structural element. The 3-dimensional model is analyzed using the latest licensed software from California Structures, Inc. (CSI). We employ the world-renowned seismic software E.T.A.B.S. for this purpose. This model is then subjected to simulated strong ground earthquake movement based on the anticipated peak ground accelerations by the 1997 UBC Code. The performance of the structure is then analyzed. Anticipated stresses at each and every structural member such as beams, columns, shear walls, slabs, and the foundation elements, are then considered in the design of said structural members.The combination of gravity, wind and seismic forces are also considered in the analysis, and form part of the rigorous calculations involved in the Structural Design of the buildings.Above considerations express that structures designed in conformity with these code provisions, if properly constructed, as per Structural Design Drawings, will most likely survive a major earthquake with such magnitude which has a 10% probability of occurring during a 50-year cycle. The code allows that the structure will suffer a minor degree of damage under strong earthquake tremors, but will not collapse and will still be serviceable. Life safety is of utmost consideration.We hope that with the above explanations we were able to address all of your concerns and should you feel the need for further inputs from our end, please feel free to call on us at a time most convenient to your good selves.We hope that we have made the issue much clearer and much easier to understand.Sincerely,Aromin & Sy + Associates, Inc.(Signed) WILSON A. SYVice-President

Thank You.