地震-介绍-earthquake

↙AlipdeBelt地中海-喜马拉雅地震带TheCircumPacificBelt环太平洋地震带EarthquakeWhyisEarthquake？Duringthedecadefrommid-2004tomid-201418great(Mw≥8.0)earthquakesoccurredglobally(∼1.8peryear),comparedto71from1900tomid-2004(∼0.68peryear),yieldingashort-termrateincreaseof265%.SixeventshadMw≥8.5.EarthquakeDefinitionandelementsClassficationEffectsofEarthquakesPredictionPrecursors（前兆）ReferencesDefinitionandElementsEarthquake：theresultofasuddenreleaseofenergyintheEarth’scrustthatcreatesseismicwaves.(seismicevent)DefinitionandElementsFocus（Hypocenter):Anearthquake’spointofinitialruptureEpicenter：thepointatgroundleveldirectlyabovethehypocenterEpicentralDistance:thedistancetoepicenterDepthoffocusIsoseismalLineClassficationOrigion：naturalearthquake（VIP）artificialearthquakeSeismicsequence:foreshockmainshockaftershockPositionoffocus：Intraplateearthquakes（板内）Interplateearthquakes（板间）ClassficationDepthoffocus：shallow-focusearthquakes(70km)mid-focusearthquakes(70-300km)Deep-focusearthquakes(300km)EffectsofearthquakesShakingandgroundrupture（振动和地表破裂）GroundruptureisavisiblebreakinganddisplacementoftheEarth’ssurfacealongthetraceofthefault,whichmaybeoftheorderofseveralmetresinthecaseofmajorearthquakes.EffectsofearthquakesLandslidesandavalanches（雪崩）Landslidesoccurwhenthestabilityoftheslopechangesfromastabletoanunstablecondition.Achangeinthestabilityofaslopecanbecausedbyanumberoffactors,actingtogetheroralone；soitgoeswithavalanches。EffectsofearthquakesFiresEarthquakescancausefiresbydamagingelectricalpowerorgaslines.Intheeventofwatermainsrupturingandalossofpressure,itmayalsobecomedifficulttostopthespreadofafireonceithasstarted（mainlyindevelopedareas）.eg：1906SanFranciscoearthquake1995GreatHanshinearthquakeEffectsofearthquakesSoilliquefaction（砂土液化）occurswhen,becauseoftheshaking,water-saturatedgranular（颗粒）material(suchassand）temporarilylosesitsstrengthandtransformsfromasolidtoaliquid.Soilliquefactionmaycauserigidstructureslikebuildingsandbridges,totiltorsinkintotheliquefieddeposits.Forexample,inthe1964Alaskaearthquake,soilliquefactioncausedmanybuildingstosinkintotheground,eventuallycollapsinguponthemselves.EffectsofearthquakesTsunami：whenanearthquakehappensoffshore，aseriesofwavesinabodyofwaterwillbecausedbythedisplacementofalargevolumeofwater。Anddatasindicatingthatmostdestructivetsunamisarecausedbyearthquakesofmagnitude7.5ormore.eg:2004Indianoceanearthquake2011TohokuearthquakeEffectsofearthquakesHumanimpactsAnearthquakemaycauseinjuryandlossoflife,roadandbridgedamage,generalpropertydamage,andcollapseordestabilization(potentiallyleadingtofuturecollapse)ofbuildings.Theaftermathmaybringdisease,lackofbasicnecessities,andhigherinsurancepremiums.PredictionEarthquakepredictionmaybeintrinsicallyimpossible.IthasbeenarguedthattheEarthisinastateofself-organizedcriticality“whereanysmallearthquakehassomeprobabilityofcascadingintoalargeevent”.Ithasalsobeenargueddecision-theoreticgroundsthatpredictionofmajorearthquakesisimpossible。PrecursorsAnimalbehaviorRadonemissions（氡气释放）Electromagneticvariations（电磁变化）ChangesinVp/Vs（P波、S波的变化）Inparticular,manycasesofreportedprecursorsarecontradictory,lackameasureofamplitude,oraregenerallyunsuitableforarigorousstatisticalevaluation.Publishedresultsarebiasedtowardspositiveresults,andsotherateoffalsenegatives(earthquakebutnoprecursorysignal)isunclear.ReferencesTheAdHocWorkingGroupontheDecember2—3,1990,EarthquakePrediction[AHWG](18October1990),EvaluationoftheDecember2-3,1990,NewMadridSeismicZonePrediction.IncludedinApp.BofSpenceetal.1993.Ammon,C.J.,Kanamori,H.,Lay,T.,Velasco,A.A.,2006.The17July2006Javatsunamiearthquake.Geophys.Res.Lett.33,L24308.ThorneLay，2015，Thesurgeofgreatearthquakesfrom2004to2014EarthandPlanetaryScienceLetters409(2015)133–146.Fidani,C.(2010).Theearthquakelights(EQL)ofthe6April2009Aquilaearthquake,inCentralItaly.NaturalHazardsandEarthSystemScience10(5):967–78.