Earthquake and its hazards
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PHIVOLCS monitors earthquakes in the Philippines using a network of over 100 seismic stations. Earthquakes are natural occurrences caused by the slow motion of tectonic plates. The Philippines is located in a seismically active area between several plates. PHIVOLCS provides information to the public on earthquake locations, intensities, and issues advisories. Larger earthquakes are inevitable given the Philippines' position between plates and presence of faults.
Earthquake and its hazards
- 1. BABY JANE T. PUNONGBAYANBABY JANE T. PUNONGBAYAN Seismological Observation and Earthquake Prediction DivisionSeismological Observation and Earthquake Prediction Division Philippine Institute of Volcanology and SeismologyPhilippine Institute of Volcanology and Seismology PHIVOLCSPHIVOLCS -- DOSTDOST UNDERSTANDINGUNDERSTANDING EARTHQUAKES ANDEARTHQUAKES AND EARTHQUAKE HAZARDSEARTHQUAKE HAZARDS
- 2. 30 unmanned stations:30 unmanned stations: 1 in1 in OrmocOrmoc 1 in1 in MaasinMaasin 29 manned stations29 manned stations 1 in Palo1 in Palo 55 seismoseismo--volcanologicalvolcanological observatoriesobservatories Metro ManilaMetro Manila micronetworkmicronetwork with 5with 5 telemeteredtelemetered seismic stationsseismic stations TemporaryTemporary HinunanganHinunangan NetworkNetwork 5 stations5 stations Network of Earthquake Monitoring Stations in the Philippines
- 3. Seismic monitoring station in El Nido, Palawan
- 4. PHIVOLCS seismologists:PHIVOLCS seismologists: earthquake huntersearthquake hunters 4,000th quake in 4 days!
- 5. PHIVOLCS: Source of earthquake information in the PhilippinesPHIVOLCS: Source of earthquake information in the Philippines Details of earthquake location:Details of earthquake location: Origin time, coordinates, depth,Origin time, coordinates, depth, source (tectonic or volcanic),source (tectonic or volcanic), generatorgenerator Intensities of affected areasIntensities of affected areas Tsunami bulletins and warningsTsunami bulletins and warnings Advisory in times of necessaryAdvisory in times of necessary evacuationevacuation Information transmitted by tri-media (tv, radio and print)
- 6. What have we learned?What have we learned? PHIVOLCS is the agency mandated toPHIVOLCS is the agency mandated to monitor earthquakes in the Philippinesmonitor earthquakes in the Philippines A seismically active area may produceA seismically active area may produce hundreds to thousands of earthquakes in ahundreds to thousands of earthquakes in a brief span of time (hours to several weeks)brief span of time (hours to several weeks)
- 7. EarthEarth Our planet is dynamic The outermost layer is broken into pieces These pieces called “plates” are moving, away or toward each other
- 8. Mantle convection is driving the earth’s tectonic platesMantle convection is driving the earth’s tectonic plates
- 9. The Earth is dynamic: Plate TectonicsThe Earth is dynamic: Plate Tectonics
- 10. The Philippines is a region between tectonic plates EQUATOR
- 11. FaultFault -- form in rocks when the stresses overcome theform in rocks when the stresses overcome the internal strength of the rock resulting in a fractureinternal strength of the rock resulting in a fracture
- 12. THE CRUST IS FRAGMENTED Tectonic plates Earthquakes are found along plate boundaries
- 13. What have we learned?What have we learned? Earthquakes are natural phenomenaEarthquakes are natural phenomena brought about by slow but powerful motionsbrought about by slow but powerful motions within the earthwithin the earth The internal motion within the EarthThe internal motion within the Earth induces deformation along the fragileinduces deformation along the fragile surface of the planetsurface of the planet Sudden ground deformation producesSudden ground deformation produces seismic waves or earthquakesseismic waves or earthquakes
- 14. A weak to violent shakingA weak to violent shaking of the ground produced byof the ground produced by the sudden movement ofthe sudden movement of rock materials below therock materials below the earth’s surface.earth’s surface.
- 15. 2. Volcanic - earthquakes produced by movement of magma beneath volcanoes 1. Tectonic - earthquakes produced by sudden movement along faults and plate boundaries TYPES OF NATURAL EARTHQUAKESTYPES OF NATURAL EARTHQUAKESTYPES OF NATURAL EARTHQUAKESTYPES OF NATURAL EARTHQUAKES
- 16. Particle Motion upon passage of different types of seismic waves P – primary wave; displacement of media along direction of propagation (up-down) S – secondary; displacement of media perpendicular to direction of wave propagation (sideways) Surface waves: 1. Love waves 2. Rayleigh waves (rotational)
- 17. SeismogramSeismogram Distance of point of observation from earthquake source is determined using the arrival times of different seismic waves, usually P and S waves
- 18. Locating the Epicenter Travel Time and earth structureTravel Time and earth structure Velocity ModelsVelocity Models Refracted and Reflected PhasesRefracted and Reflected Phases
- 19. FAULT FOCUS vs. EPICENTERFOCUS vs. EPICENTER
- 20. • at least 20 earthquakes are recorded per day • 4 – 5 earthquakes are felt per week Instrumental Data (ISC) 1964-1999 Philippines is an earthquake country !
- 21. M7.5 01 Apr 1955 Lanao (291/713) M7.3 02 Aug 1968 Casiguran (270/600) M7.3 07 Apr 1970 Baler (15/200) 17 Aug 1976 Moro Gulf (3,739/8,000) 16 July 1990 Luzon (1,283/2,786) 15 November 1994 Mindoro (78)
- 22. Fact: The Philippine Archipelago has a complex tectonic setting with several trenches and many active faults
- 23. perceived strength of an earthquake based on relative effect to people and structures; generally higher near the epicenter based on instrumentally derived information and correlates strength with the amount of total energy released at the earthquake’s point of origin Two ways of describing the strength of an earthquakeTwo ways of describing the strength of an earthquakeTwo ways of describing the strength of an earthquakeTwo ways of describing the strength of an earthquake 1.... Intensity 2.2.2.2. Magnitude
- 24. MagnitudeMagnitude <energy><energy> Compares logarithmic of amplitude withCompares logarithmic of amplitude with distance from epicenterdistance from epicenter Types depending on instrumentation:Types depending on instrumentation: Period (s)Period (s)DescriptionDescriptionNameName MomentMoment MagnitudeMagnitude SurfaceSurface MagnitudeMagnitude BodyBody MagnitudeMagnitude LocalLocal MagnitudeMagnitude MwMw MsMs MbMb MlMl > 200> 200 2020 1.01.0 –– 5.05.0 0.10.1 –– 1.01.0 WoodWood-- Anderson typeAnderson type seismographseismograph
- 25. RICHTER MAGNITUDE SCALERICHTER MAGNITUDE SCALE Earthquakes with M over 9 have never occurred since the data based on the seismographic observations became available. 1010 M over 9 have never occurred since the data based on the seismographic observations became available. 99 M 8 to 9 are the "great earthquakes" occurring once or twice a year. When in land areas, damages affect wide areas. When under the sea, considerable tsunamis are produced. Many aftershocks occur in areas approximately 100 to 1,000 kilometers in diameter. 88 M 7 to 8 are the "major earthquakes“; can cause considerable damages near epicenters; may generate tsunamis. 77 M 6 to 7 are "strong earthquakes“; accompanied by local damages near epicenters.66 M 5 to 6 are "earthquakes with moderate strength“; felt over the wide areas; some of them cause small local damages near the epicenter. 55 M 4 to 5 are "feeble shocks" where damages are not usually reported.44 M 3 to 4 are "very feeble shocks" and only felt near the epicenter.33 M below 3 are "hardly perceptible shocks" and are not felt.22 magnitude below 1 are only detectable when an ultra sensitive seismometer is operated under favorable conditions. 11
- 26. • There are different types of magnitude depending on type of seismograph used: Ml, mb, Ms, Mw, Mwp, etc. • Magnitude scale is open ended (no limit)
- 27. 1960 Chile earthquake (strongest1960 Chile earthquake (strongest recorded earthquake)recorded earthquake) 9.5 estimate for a 2 km rocky meteorite impacting at 25 km/s1 teraton10.0 Catastrophic to whole earthCatastrophic to whole earth12.0 2004 Indian Ocean earthquake32 gigatons9.3 1990 Baguio (Luzon) earthquake (67,000x hiroshima) 1 gigaton7.8 Nagasaki atomic bomb32 kiloton5.0 Small atomic bomb1 kiloton4.0 Construction site blast32 kg (70 lb)1.0 large Hand grenade 5.6 kg (12.4 lb) 0.5 Example Approximate TNT for Seismic Energy Yield Richter Approximate Magnitude (Ml)00
- 28. Indonesia 2004
- 29. INTENSITY • Decreases with distance from source • can be gauged by Assumption students!! Very easy…
- 30. INTENSITY VIII INTENSITY IX INTENSITY VIII INTENSITY VII
- 31. What have we learned?What have we learned? Magnitude = instrumentsMagnitude = instruments Intensity = personal observationsIntensity = personal observations An increase of one unit on the Richter Scale corresponds toAn increase of one unit on the Richter Scale corresponds to approximately a 30approximately a 30--fold increase in the total energy released.fold increase in the total energy released. Large magnitude earthquakes have occurred in theLarge magnitude earthquakes have occurred in the Philippines in the pastPhilippines in the past Large magnitude earthquakes are inevitable in the PhilippinesLarge magnitude earthquakes are inevitable in the Philippines because of its geodynamic setting and the presence of faultsbecause of its geodynamic setting and the presence of faults YOU and your class may contribute in intensity reporting!YOU and your class may contribute in intensity reporting! Basic seismology deciphers information about the earth andBasic seismology deciphers information about the earth and its movements using the imprint of the passing of seismicits movements using the imprint of the passing of seismic waveswaves
- 32. Basic TermsBasic Terms SeismologySeismology -- sciencescience SeismicSeismic -- pertaining to earthquakepertaining to earthquake SeismographSeismograph -- instrumentinstrument SeismogramSeismogram –– record of earthquakerecord of earthquake AftershockAftershock -- following thefollowing the mainshockmainshock ForeshockForeshock ––before abefore a mainshockmainshock
- 33. Seismic Hazards:Seismic Hazards: dangers posed by large earthquakesdangers posed by large earthquakes • Ground Shaking - shake • Ground Rupture - cut • Liquefaction - very soft soil • Landslides - slope failure • Tsunami - waves Secondary Hazards: •Fire •Lateral spreading, etc.
- 34. Intense shaking, earthquake of Kobe, Japan 1995Intense shaking, earthquake of Kobe, Japan 1995
- 35. intense shaking + weak structure = building damage or collapse Ex. Hyatt Hotel in Baguio City after the magnitude 7.8 earthquake of July 16, 1990
- 36. USA
- 37. INDIA
- 38. Ground rupture with vertical displacementGround rupture with vertical displacement
- 39. Intense shaking + loosely hanged objects =Intense shaking + loosely hanged objects = falling objectsfalling objects
- 40. Hazard 2:Hazard 2: GROUND RUPTUREGROUND RUPTURE fissuringfissuring or faulting along the surface The creation of new or the renewal of movements of old fractures, oftentimes with the two blocks on both sides moving in opposite directions
- 43. •• Reverse FaultReverse Fault Photo of Nojima Fault in Japan, fissured during the M=7.2 1995 Kobe earthquake
- 44. Ground rupture and fissuring Taiwan Earthquake, 1999
- 48. Active Fault: trace certain Active Fault: trace approximate Offset stream Legend: Faulted outcrop (Brgy. Salog, Leyte) Salog Elementary School, Leyte
- 49. Hazard 3: LiquefactionHazard 3: Liquefaction -- a process that transforms the behavior of a body of sediment from that of a solid to that of a liquid
- 50. Liquefaction in Hinunangan, Southern Leyte July 19, 2007 Photo courtesy of PHIVOLCS HINUNANGAN JULY 2007 QRT Team Brgy. Badiangon Brgy. Das-ay
- 51. Liquefaction:Liquefaction: The ground loses strength and structuresThe ground loses strength and structures built on top of it may sink and tilt...built on top of it may sink and tilt...
- 52. EarthquakeEarthquake--induced Landslidesinduced Landslides Occurrence of a strong earthquakeOccurrence of a strong earthquake Elevated areas:Elevated areas: steeper slopes, more pronesteeper slopes, more prone Thick soil cover:Thick soil cover: more loose materials to fallmore loose materials to fall Proximity to fault:Proximity to fault: stronger shaking in areasstronger shaking in areas near the earthquakenear the earthquake--generating faultgenerating fault Water saturation of materials:Water saturation of materials: wet slopeswet slopes easier to landslideeasier to landslide READY MAPPING 2007: Dr. Arturo Daag and Ms. Angela Montes
- 54. Hazard 4:Hazard 4: Landslides andLandslides and RockfallsRockfalls
- 55. HinunanganHinunangan, Southern, Southern LeyteLeyte July 19, 2007 11:10 PMJuly 19, 2007 11:10 PM Magnitude 5.5 EarthquakeMagnitude 5.5 Earthquake Intensity VII in Hinunangan Landslide in Brgy. Biasong Photo: Punongbayan, BJT 2007
- 56. Tension cracks inTension cracks in BrgyBrgy.. ManalogManalog July 19, 2007July 19, 2007 (Intensity VII in(Intensity VII in HinunanganHinunangan))
- 57. Ground FailureGround Failure -- LandslideLandslide INTENSE shaking +INTENSE shaking + SlopeSlope VegetationVegetation Water contentWater content PrePre--existingexisting structuresstructures
- 58. Secondary Hazard: FireSecondary Hazard: Fire
- 59. COMMON QUESTIONS:COMMON QUESTIONS: Can earthquakes be predicted?Can earthquakes be predicted? Is there a fault passing through yourIs there a fault passing through your school?school? Where is theWhere is the MarikinaMarikina Fault?Fault? Is there a risk of tsunami inIs there a risk of tsunami in MetroManilaMetroManila?? Who are at risk?Who are at risk?
- 61. ~3 km
- 62. WVFWVF Maximum 4mMaximum 4m average 2maverage 2m alongsidealongside Manila BayManila Bay Will notWill not occuroccur TsunamiTsunami SeismicSeismic IntensityIntensity (PEIS)(PEIS) FaultFault MechanismMechanism MagnitudeMagnitude ModelModel Almost VIII,Almost VIII, IX alongsideIX alongside MarikinaMarikina River andRiver and Manila BayManila Bay Inland FaultInland Fault 7.27.2 ModelModel 0808 VIII at West ofVIII at West of MetropolitanMetropolitan Mania, VII atMania, VII at other areaother area SubductionSubduction 7.97.9 ModelModel 1313 Is there a possibility of a big earthquake inIs there a possibility of a big earthquake in MetroManilaMetroManila?? TheThe MetroManilaMetroManila Earthquake Impact Reduction Study (MMEIRS)Earthquake Impact Reduction Study (MMEIRS) Some Earthquake Models/Scenario for Metro ManilaSome Earthquake Models/Scenario for Metro Manila
- 63. HAZARD MAPPING Ex. Groundshaking for West Valley Fault Mag=7.2 Scenario 08 INVENTORY OF CRITICAL FACILITIES Ex. Schools
- 64. PEIS Intensity VIIIPEIS Intensity VIII –– Very DestructiveVery Destructive People are panicky and find it difficult to stand even outdoorsPeople are panicky and find it difficult to stand even outdoors Many wellMany well--built buildings are considerably damagedbuilt buildings are considerably damaged Concrete dikes and foundations of bridges destroyed by groundConcrete dikes and foundations of bridges destroyed by ground settlingsettling Railway tracks may be broken; tombstones may be displaced,Railway tracks may be broken; tombstones may be displaced, twisted or overturnedtwisted or overturned Utility posts, towers and monuments may tilt or toppleUtility posts, towers and monuments may tilt or topple Water and sewer pipes may be bent, twisted or brokenWater and sewer pipes may be bent, twisted or broken Sinking or titling of structures due to liquefactionSinking or titling of structures due to liquefaction Landslides andLandslides and rockfallsrockfalls; Boulders thrown out near epicenter; Boulders thrown out near epicenter Fissures or rupture observedFissures or rupture observed Water splashes over dikes orWater splashes over dikes or oror riverbanksriverbanks
- 66. August 2, 1968 (Ms 7.3); Casiguran Fault-East Luzon Trench region The Ruby Tower in Binondo, Manila, a large six-storey building containing 38 commercial units in its first two floors and 76 residential units in its upper four floors; Most of the building collapsed except for a part of the northern end of its first and second floors. 268 persons died and 260 were injured.
- 67. ESTIMATED IMPACTS OF WORST CASE SCENARIO EARTHQUAKEESTIMATED IMPACTS OF WORST CASE SCENARIO EARTHQUAKE (Magnitude=7.2 West Valley Fault)(Magnitude=7.2 West Valley Fault) 13%13% 170,000170,000 heavily damagedheavily damaged or collapsedor collapsed Residential buildingsResidential buildings 25.6% or25.6% or 350,000350,000 moderatelymoderately damageddamaged 34,000,34,000, 90% from pressure of90% from pressure of collapsed buildingcollapsed building deaddeadHuman LossHuman Loss With population of 9,932,560With population of 9,932,560 120,000120,000injuredinjured 2020 –– 25 %25 %Partly DamagedPartly Damaged 88 -- 10 %10 %Heavily DamagedHeavily DamagedPublic Purpose Buildings:Public Purpose Buildings: Schools 1412, Hospitals 177, FireSchools 1412, Hospitals 177, Fire Fighting 124, Police 43, MMDCCFighting 124, Police 43, MMDCC Organizations and 17 LGU CityOrganizations and 17 LGU City and Municipal Halls 53and Municipal Halls 53 Four out of ten buildings and houses will be damaged
- 68. PHIVOLCS has the knowledge, it is ourPHIVOLCS has the knowledge, it is our mission to prepare the public.mission to prepare the public. Some of our information andSome of our information and earthquake campaigns:earthquake campaigns: Nationwide lectures and seminarsNationwide lectures and seminars Earthquake drillsEarthquake drills Tsunami warning systemsTsunami warning systems Tsunami warning signageTsunami warning signage Tsunami drillsTsunami drills
- 69. Make the drill a nice learning experience …
- 70. http://www.phivolcs.dost.gov.ph For requests/inquiries: Director Renato U. Solidum, Jr. PHIVOLCS Bldg., C.P. Garcia Ave. U.P. Diliman, Q.C. 1101 Tel: 426-1468 loc. 112 or 124 or 125 Fax: 927-8366