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1、ÓBirkhaÈuserVerlag,Basel,2001Pureappl.geophys.158(2001)211±2400033±4553/01/020211±30$1.50+0.20/0PureandAppliedGeophysicsImprovingRegionalSeismicEventLocationinChina111LEEK.STECK,AARONA.VELASCO,ALLENH.COGBILL,and1HOWARDJ.PATTONAbstractÐInaneorttoimproveourabilit
2、ytolocateseismiceventsinChinausingonlyregionaldata,wehavedevelopedempiricalpropagationpathcorrectionsandappliedsuchcorrectionsusingtraditionallocationroutines.Thusfar,wehaveconcentratedoncorrectionstoobservedParrivaltimesforcrustaleventsusingtravel-timeobservat
3、ionsavailablefromtheUSGSEarthquakeDataReports,theInternationalSeismicCentreBulletin,thepreliminaryInternationalDataCenterReviewedEventBulletin,andourowntravel-timepicksfromregionaldata.Locationgroundtruthforeventsusedinthisstudyrangesfrom25kmforwell-locatedtele
4、seimicevents,downto2kmfornuclearexplosionslocatedusingsatelliteimagery.Wealsouseeighteventsforwhichdepthisconstrainedusingseveralwaveformmethods.WerelocateeventsusingtheEvLocalgorithmfromaregionencompassingmuchofChina(latitude20°±55°N;longitude65°±115°E).Weobse
5、rvethattravel-timeresidualsexhibitadistance-dependentbiasusingIASPEI91asourbasemodel.Toremedythisbias,wehavedevelopedanew1-DmodelforChina,whichremovesasigni®cantportionofthedistancebias.ForindividualstationshavingsucientP-waveresidualdata,weproduceamapoftheregi
6、onaltravel-timeresidualsfromallwell-locatedteleseismicevents.Residualsareusedonlyiftheyaresmallerthan10sinabsolutevalueandiftheseismiceventislocatedwithaccuracybetterthan25km.Fromtheresidualdata,correctionsurfacesareconstructedusingmodi®edBayesiankriging.Modi®e
7、dBayesiankrigingoersustheadvantageofprovidingwell-behavedinterpolantsandtheirerrors,butrequiresthatwehaveadequateerrorestimatesassociatedwiththetravel-timeresidualsfromwhichtheyareconstructed.ForourP-waveresidualerrorestimate,weusethesumofmeasurementandmodeling
8、errors,wheremeasurementerrorisbasedonsignal-to-noiseratioswhenavailable,andonthepublishedcatalogestimateotherwise.Ourmodelingerrororiginatesfromthevarianceoftravel-timeresid
