REAL-TIME SEISMOLOGY AND EARTHQUAKE DAMAGEMITIGATI

11Mar200522:18ARAR233-EA33-06.texXMLPublishSM(2004/02/24)P1:JRX10.1146/annurev.earth.33.092203.122626Annu.Rev.EarthPlanet.Sci.2005.33:195–214doi:10.1146/annurev.earth.33.092203.122626Copyrightc
2005byAnnualReviews.AllrightsreservedFirstpublishedonlineasaReviewinAdvanceonDecember2,2004REAL-TIMESEISMOLOGYANDEARTHQUAKEDAMAGEMITIGATIONHirooKanamoriSeismologicalLaboratory,CaliforniaInstituteofTechnology,Pasadena,California91125;email:[e-mail]lywarning,earthquakerupture,earthquakeprediction,hazardmitigation,structuralcontrol■AbstractReal-timeseismologyreferstoapracticeinwhichseismicdataarecollectedandanalyzedquicklyafterasignificantseismicevent,sothattheresultscanbeeffectivelyusedforpostearthquakeemergencyresponseandearlywarning.Asthetechnologyofseismicinstrumentation,telemetry,computers,anddatastoragefacilityadvances,thereal-timeseismologyforrapidpostearthquakenotificationisessentiallyestablished.Researchforearlywarningisstillunderway.Twoapproachesarepossible:(a)regionalwarningand(b)on-site(orsite-specific)warning.In(a),thetraditionalseismologicalmethodisusedtolocateanearthquake,determinethemagnitude,andestimatethegroundmotionatothersites.In(b),thebeginningofthegroundmotion(mainlyPwave)observedatasiteisusedtopredicttheensuinggroundmotionatthesamesite.Aneffectiveapproachtoon-sitewarningisdiscussedinlightofearthquakerupturephysics.INTRODUCTIONSeismologyprovidesuswithkeyinformationonthestructureofEarthaswellasthephysicsofearthquakesandothergeophysicalprocesses.Atthesametime,ithasanimportantroleinreducingtheimpactofearthquakesonoursociety.Ac-curatepredictionsofearthquakeswouldbeobviouslyeffectiveforreducingthedamagecausedbyearthquakes.Unfortunately,thenucleationandrupturepro-cessesofearthquakesaregovernedbymanyfactorsthatinteractwitheachotherinacomplexfashion.Becauseofthiscomplexinteraction,itisdifficulttomakeaccuratepredictionsofearthquakes.Anotherpracticalwaytouseseismologyforeffectivedamagemitigationisreal-timeseismology.Real-timeseismologynormallyreferstoapracticeinwhichseismicdataarecollectedandanalyzedquicklyafterasignificantseismiceventsothattheresultscanbeeffectivelyusedforpostearthquakeemergencyresponseand,underfavorablecircumstances,earlywarning.Also,gainingscientificinformationquicklyhasitsownmeritforbet-terunderstandingtheprocessthroughstrategicallydeployedinstrumentationandplannedfieldworks.0084-6597/05/0519-0195$20.00195Annu.Rev.EarthPlanet.Sci.2005.33:195-214.Downloadedfromarjournals.annualreviews.orgbyCaliforniaInstituteofTechnologyon12/14/07.Forpersonaluseonly.11Mar200522:18ARAR233-EA33-06.texXMLPublishSM(2004/02/24)P1:JRX196KANAMORIThetimescaleinvolvedinreal-timeseismologyis,inmostcases,minutestohours.Inthesecases,bythetimeinformationisreleasedtheearthquakeisover,andtheinformationisusedmainlyforpostearthquakeemergencyresponse,plan-ningfieldworks,deployinginstruments,andpublicinformationservices.Iftheinformationcanbegainedinamatterofsecondstominutes,itcanbeusedforearlywarningpurposesinwhichinformationontheseverityofseismicshakingreachestheusersbeforeshakingbeginsattheusersite.Thetechnologyforthisisfarmoredifficultthanthatforthepostearthquakeinformationsystem,andactiveresearchisnowunderway.Recentreviewsonreal-timeseismologyandearthquakeearlywarningsystems(EWSs)arefoundinKanamorietal.(1997)andLee&Espinoza-Aranda(2002),respectively.Also,abook(inJapanese)byKikuchi(2003)coversabroadaspectofreal-timeseismology.Here,wefirstbrieflyreviewthehistoryandthepresentstatus,andthenfocusonthescientificbasisofearthquakeearlywarning.HISTORYRapidNotificationofEarthquakeInformationInthelate1960sto1970s,theU.S.GeologicalSurvey(USGS)inMenloParkdevel-opedatelemeteredearthquakemonitoringsystemincentralCaliforniathatenabledrapidlocationandmagnitudedeterminationofregionalearthquakes(Stewartetal.1971,Lee&Stewart1981).Ataboutthesametime,USGSandtheCaliforniaInstituteofTechnology(Caltech)jointlyoperatedatelemeteredseismicnetworkinsouthernCalifornia.Also,numerousreal-timemonitoringsystemswerede-velopedandimplementedworldwide.Thebasictechnologyfortelemeteringandrapid(i.e.,nearreal-time)processingofseismicdatahadbeenfullydevelopedbytheendofthe1980s.Takingadvantageofthesedevelopments,rapidearthquakenotificationsys-temsweredevelopedwithspecialemphasisoninvolvingtheusersofsuchinfor-mation.TheCaltech/USGSBroadcastofEarthquakes(CUBE)(Kanamorietal.1991)developedinsouthernCaliforniaandtheRapidEarthquakeDataInte-grationProject(REDI)(Geeetal.1996,2003)developedinnorthernCalifor-niaareamongtheearlyexamples.Thesesystemsallowearthquakeparameterstobebroadcasttousersafewminutesafteranearthquakeoccurs.Afterthedeploy-mentofadensebroadbandseismicnetworkinsouthernCalifornia,calledTriNet(Morietal.1998,Haukssonetal.2001),amoregeneralnotificationsystem,ShakeMap(Waldetal.1999a,b),wasdevelopedinwhichtheobservedground-motiondataarerapidlyprocessedtoproduceamapshowingthedistributionofstronggroundmotions.ShakeMapsaregeneratedautomatically,followingmod-erateandlargeearthquakes,withinseveralminutesoftheearthquakeorigintime(Goltz2003).InJapan