简介：

简介：

简介：IntheSoutheastMarginoftheTibetanPlateau,low-velocitysedimentarylayersthatwouldsignificantlyaffecttheaccuracyoftheH-κstackingofreceiverfunctionsarewidelydistributed.Inthisstudy,weuseteleseismicwaveformdataof475eventsfrom97temporarybroadbandseismometersdeployedbyChinArrayPhaseItoobtaincrustalthicknessesandPoisson’sratioswithintheChuxiong-SimaoBasinandadjacentarea,employinganimprovedmethodinwhichthereceiverfunctionsareprocessedthrougharesonance-removalfilter,andtheH-κstackingistime-corrected.Resultsshowthatthecrustalthicknessrangesfrom30to55kminthestudyarea,reachingitsthickestvalueinthenorthwestandthinningtowardsouthwest,southeastandnortheast.TheapparentvariationofcrustalthicknessaroundtheRedRiverFaultsupportstheviewofsoutheasternescapeoftheTibetanPlateau.RelativelythincrustalthicknessinthezonebetweenChuxiongCityandtheRedRiverFaultindicatespossibleupliftofmantleinthisarea.ThepositivecorrelationbetweencrustalthicknessandPoisson’sratioislikelytoberelatedtolowercrustthickening.Comparisonofresultsobtainedfromdifferentmethodsshowsthattheimprovedmethodusedinourstudycaneffectivelyremovethereverberationeffectofsedimentarylayers.

简介：Irregularsurfaceflattening,whichisbasedonaboundaryconforminggridandthetransformationbetweencurvilinearandCartesiancoordinatesystems,isamathematicalmethodthatcanelegantlyhandleirregularsurfaces,buthasbeenlimitedtoobtainingfirstarrivalsonly.Bycombiningamultistageschemewiththefast-sweepingmethod(FSM,themethodtoobtainfirst-arrivaltraveltimeincurvilinearcoordinates),thereflectedwavesfromacrustalinterfacecanbetracedinatopographicmodel,inwhichthereflectedwavefrontisobtainedbyreinitializingtraveltimesintheinterfaceforupwindbranches.Alocaltriangulationisappliedtomakeaconnectionbetweenvelocityandinterfacenodes.Thenajointinversionoffirst-arrivalandreflectiontraveltimesforimagingseismicvelocitystructuresincomplexterrainsispresented.Numericalexamplesallperformwellwithdifferentseismicvelocitymodels.Theincreasingtopographiccomplexityandevenuseofahighcurvaturereflectorinthesemodelsdemonstratethereliability,accuracyandrobustnessofthenewworkingscheme;checkerboardtestingillustratesthemethod’shighresolution.Noisetolerancetestingindicatesthemethod’sabilitytoyieldpracticaltraveltimetomography.Furtherdevelopmentofthemultistageschemewillallowotherlaterarrivalstobetracedandusedinthetraveltimeinversion.