简介：EstimatedGreen'sfunction(EGF)betweenstationshasbeenextractedfromambientseismicnoise,directsurfacewaveandcodawaves.Itisalsoconfirmedbylaboratoryexperimentsonultrasonicsandtheoreticalderivationsassumingdiffusivewavefield,equi-partitionofmodesorrandomsourcesonanenclosedsurface.Thismethodprovidesanewapproachtostudythecrustandmantlestructureatregionalscale,continentalscaleandglobalscale.Followingtheachievementswithseismometerrecords,therecordsofinfrasonicstation,hydrophoneandmicrophonewerealsousedtoobtaintheEGFsofdifferentwavefields.Sincesuperconductinggravimeterisabetterlongperiodinstrumentthanregularseismometer,EGFatlongerperiodisexpectedtobeobtainedwiththecrosscorrelationofgravitydata.Inthispaper,wewillshowtheEGFsextractedbycross-correlationsbetweenthesuperconductinggravimetersandtheseismometers.Boththetraveltimesanddispersioncurvesobtainedfromdifferentdatatypesareconsistent.Theresultshowsthatitispossibletoretrievethedeepstructurebythecrosscorrelationofgravitydata.

简介：BasedonthesolutionsoftheGreen'sfunctionforasaturatedporousmediumobtainedbytheauthors,andusingtransformationofaxisymmetriccoordinates,Sommerfeldintegralsandsuperpositionoftheinfluencefieldonafreesurface,theauthorshaveobtaineddisplacementsolutionsofasaturatedporousmediumsubjectedtoatorsionalforceinahalf-space.Therelationshipcurvesofthedisplacementsolutionsandvariousparameters(permeability,frequency,etc.)underactionofaunitoftorquearealsogiveninthispaper.TheresultsareconsistentwithpreviousReissner'ssolutions,whereatwo-phasemediumdecaystoasingle-phasemedium.Thesolutionisusefulinsolvingrelevantdynamicproblemsofatwophasesaturatedmediuminengineering.

简介：ThisstudyproposesaGreen’sfunction,anessentialrepresentationofwater-saturatedgroundundermovingexcitation,tosimulategroundbornevibrationfromtrains.First,generalsolutionstothegoverningequationsofporoelasticmediumarederivedbymeansofintegraltransform.Secondly,thetransmissionandreflectionmatrixapproachisusedtoformulatetherelationshipbetweendisplacementandstressofthestratifiedground,whichresultsinthematrixoftheGreen’sfunction.ThentheGreen’sfunctioniscombinedintoatrain-track-groundmodel,andisverifiedbytypicalexamplesandafieldtest.Additionalsimulationsshowthatthecomputedgroundvibrationattenuatesfasterintheimmediatevicinityofthetrackthaninthesurroundingarea.Thewavelengthofwheel-railunevennesshasanotableeffectoncomputeddisplacementandporepressure.Thevariationofvibrationintensitywiththedepthofgroundissignificantlyinfluencedbythelayeringofthestratasoil.WhenthetrainspeedisequaltothevelocityoftheRayleighwave,theMachconeappearsinthesimulatedwavefield.TheproposedGreen’sfunctionisanappropriaterepresentationforalayeredgroundwithshallowgroundwatertable,andwillbehelpfultounderstandthedynamicresponsesofthegroundtocomplicatedmovingexcitation.

简介：Alargeearthquake(MW=7.6)occurredinJiji(Chi-Chi),Taiwan,ChinaonSeptember20,1999,andwasfollowedbymanymoderate-sizeshocksinthefollowingdays.TwoofthelargestaftershockswiththemagnitudesofMW=6.1andMW=6.2,respectively,wereusedasempiricalGreen(sfunctions(EGFs)toobtainthesourcetimefunctions(STFs)ofthemainshockfromlong-periodwaveformdataoftheGlobalDigitalSeismographNetwork(GDSN)includingIRIS,GEOSCOPEandCDSN.FortheMW=6.1aftershockofSeptember22,therewere97pairsofphasesclearenoughfrom78recordingsof26stations;fortheMW=6.2aftershockofSeptember25,therewere81pairsofphasesclearenoughfrom72recordingsof24stations.Foreachstation,2typesofSTFswereretrieved,whicharecalledP-STFandS-STFduetobeingfromPandSphases,respectively.Totally,178STFindividualswereobtainedforsource-processanalysisofthemainshock.Itwasnoticedthat,ingeneral,STFsfrommostofthestationshadsimilaritiesexceptthatthoseinspecialazimuthslookeddifferentoroddduetothemechanismdifferencebetweenthemainshockandtheaftershocks;andindetail,theshapesoftheSTFsvariedwithazimuth.BothofthemreflectedthestabilityandreliabilityoftheretrievedSTFs.ThecomprehensiveanalysisofthoseSTFssuggestedthatthiseventconsistedoftwosub-events,thetotaldurationtimewasabout26s,andontheaverage,thesecondeventwasabout7slaterthanthefirstone,andthemoment-rateamplitudeofthefirsteventwasabout15%largerthanthatofthesecondone.

简介：利用转换函数的方法对乾陵、泾阳、周至台1991—2002年地磁资料进行了计算处理，对关中各台地磁转换函数的变化特征进行了初步分析探讨。结果表明：不同周期的转换函数A、B以及总方差σz和△αρ在震前有明显变化；转换函数异常幅度不仅与周期有关，也和地震的震中距和震级有关。

简介：本文采取将经验格林函数法与随机有限断层法相结合的方式，突出体现了各自方法的优点，通过经验格林函数法确定地震震源参数，用随机有限断层法计算参数、检验其合理性。利用1998年新疆阿图什M6．9级地震的肘L4．7级余震记录，合成了这次地震的最大余震Ms6．0级地震的加速度记录，并将合成的结果与实际记录在频域和时域做了对比，分析研究了地震动特征和这次最大余震的可能破裂特征。同时对经验格林函数法需进一步改进的方向进行了探讨。