地震波传播模拟动画ppt课件

,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,Amajor7.7earthquakeoccurredTuesday205km(125miles)west-northwestofSibolga,Sumatra,Indonesia.Therewaswidespreadpanicasresidentsrushedtohigherground.Localmediareportthathundredsofhouseshavebeendamaged,andthereareelectricityblackoutsacrosstheprovince.Followingtheearthquake,peopleremainedoutonthestreets,waryofaftershocks.,USGS,ResidentssitonatruckastheypreparetofleeafteranearthquakeinBandaAcehonSumatraisland,Indonesia,Tuesday,April6,2010.A7.7earthquakeshookIndonesiasnorthwestislandofSumatraearlyTuesday,promptingabrieftsunamiwarningandsendingresidentsrushingforhigherground.(APPhoto/HeriJuanda),1,TheredstarshowstheepicenteroftheearthquakewhilethearrowsshowthedirectionofmotionoftheAustralia-IndianPlate.Atthelocationofthisearthquake,theAustralia-IndianPlatemovesnorth-northeastwithrespecttotheSundamicroplateatavelocityofapproximately60-65mm/yr.TheSundatrenchaxisstrikesapproximatelyN37W.TheIndianOceancrustismovinginanazimuthofN23ErelativetoSoutheastAsia,givinganangleofobliquityof60.,UNAVCO,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,2,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,ThesubductionzonesurroundingtheimmediateregionofthiseventlastslippedduringtheM8.6earthquakeofMarch2005,andtodaysevent(redstar)appearstohaveoccurredwithintherupturezoneofthatearthquake.Withinafewyears,almosttheentirelengthoftheSumatramegathrusthasruptured:twoM7.3earthquakes125kmtothenorthin2002and2008;aM9.1earthquakethatrupturedtowithin125kmnorthofthisearthquakein2004;aM7.9earthquake250kmtothesouthin2007;aM8.4earthquake375kmtothesouthin2007;andaM7.5earthquake260kmtothesouthnearin2009.,NASA,Earthquake,3,TheIndonesianregionisoneofthemostseismicallyactivezonesoftheearth.Themapontherightshowshistoricearthquakeactivityneartheepicenter(star)from1990topresent.Asshownonthecrosssection,earthquakesareshallow(orangedots)attheSundaTrench(purpleline)andincreaseto300kmdepth(bluedots)towardsthenortheastastheAustralia-IndianPlatedivesbeneaththeSundamicroplate.TheearthquakeofApril6,2010nicelyfitsthepatternofdepthsforearthquakesthatoccuronthesubsurfaceinterfacebetweentheAustraliaIndianPlateandtheSundamicroplate.,A,A,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,USGS,4,USGS,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,Inmostsubductionzones,motionofthesubductedplateisnearlyperpendiculartothetrenchaxis(purpleline).Insomecases,forexampleSumatra,theconvergentmotionisobliquetothetrenchandastrike-slipfaultisobservedrunningnearoralongthevolcanicchain(greenline).,ThegeographyofIndonesiaisdominatedbyvolcanoesthatareformedduetosubductionoftheAustralia-IndianPlatebeneaththeSundamicroplate.,5,ThisSumatraearthquakeoccurredasaresultofthrustfaultingonornearthesubductioninterfaceplateboundarybetweentheAustralia-IndiaandSundaplates.Onthebasisofthe,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,USGSCentroidMomentTensorSolution,Thetensionaxis(T)reflectstheminimumcompressivestressdirection.Thepressureaxis(P)reflectsthemaximumcompressivestressdirection.,IdealizedFocalMechanismforThrustFault,currentlyavailablefaultmechanisminformationandearthquakedepth,itislikelythatthisearthquakeoccurredalongtheplateinterface.,USGS,6,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,NOAA,ThailandMeteorologicalDepartment(TMD)STB-SAICTsunamiBuoy(DARTIIpayload),Thismapshowsprojectedtsunamitraveltimesfromthisearthquake.Thismapindicatesforecastedtimesonly,notthatawavetravelingthosedistanceshasactuallybeengenerated.Tsunamimonitoringsystemshavebeenstrategicallydeployednearregionswithahistoryoftsunamigeneration,toensuremeasurementofthewavesastheypropagatetowardscoastalcommunitiesandtoacquiredatacriticaltoreal-timeforecasts.,Anearbytsunamibuoydetectedasmallelevationinwaveheightfromthisearthquake(indicatedinredonthegraphbelow).ThiscausedalocaltsunamiwatchtobeissuedforIndonesiabutthatwatchhasnowbeencancelled.,7,TherecordoftheM7.7NorthernSumatra,IndonesiaearthquakeontheUniversityofPortlandseismometer(UPOR)isillustratedbelow.,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,8,Portlandisabout13,408km(8331miles,120.79degrees)fromthelocationofthisearthquake.,DirectPandSwavescannottraveltostationsmorethanepicentraldistance103becauseofthelargedecreaseinwavevelocitiesacrosstheboundarybetweenthemantleandtheliquidoutercore.ThereisashadowzonefordirectPwavesintherange103103becausetheliquidoutercoreblocksSwavesthatcannottravelthroughliquids.,PPisacompressivewavethattraveledthroughEarthsmantleandbouncedmidwaybetweentheepicenterandPortland(arrived20minutes15seconds);SSisashearwavethatalsobouncedmidwaybetweentheepicenterandPortland(arrived36minutes44seconds).,Surfacewaveenergyrequiredapproximately51minutes6secondstotravelaroundtheperimeteroftheEarthfromSumatra,IndonesiatoPortland,Oregon.,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,9,Magnitude7.7NORTHERNSUMATRA,INDONESIATuesday,April6,2010at22:15:02UTC,QuickTimeRequiredAnimationexplainingtheseismicshadowzone.EpicentraldistanceistheangleformedbytheintersectionofthelinefromtheearthquaketoEarthscenterwiththelinefromtheobservingpointtotheEarthscenter.Swavesareseenuptoadistanceof104fromanearthquake,butdirectSwavesarenotrecordedafterthis