简介：AdenseseismicnetworkwasinstalledinthecapitalregionofChinainrecentyears,whichmakesitpossibletoresolvethefocalmechanismsofsmallearthquakes.Wegatheredlargeearthquakefocalmechanismsfromthelastfiftyyearsandmoderateorsmallearthquakefocalmechanismsfrombetween2002and2004,andcalculatedthepresenttectonicstressfieldofthecapitalregionbythegridsearchmethod,whichweighsdifferentsizedearthquakesandcanimprovetheaccuracyofthestressfieldinversion.Theanalysisofinversionresultsofdifferentsub-regionsshowsthattheazinuthofthemaximumprincipalcompressivestressaxisisNE43°-86°intheBeijing-Zhangjiakou-Datongarea,NE38°-86°intheTangshanarea,andNE79°-81°intheXingtaiarea.Inversionresultsofthispaperaresimilartopreviousresults,whichprovesthecorrectnessoftheapproach.Asrevealedbytheresults,thestressfieldofthecapitalregionischaracterizedbyoverallconsistencyandsub-regionaldifferences.Thisstudyprovidesreferenceforearthquakemechanismexplanationandgeodynamicsresearch.

简介：Twoaspectsofanewmethod,whichcanbeusedforseismiczoning,areintroducedinthispaper.Ontheonehand,theapproachtoestimatebvalueandannualactivityrateproposedbyKijkoandSellevollneedstousetheearthquakecatalogue.Theexistingearthquakecataloguecontainsbothhistoricalandrecentinstrumentaldatasetsanditisinadequatetouseonlyonepart.Combiningthelargenumberofhistoricaleventswithrecentcompleterecordsandtakingthemagnitudeuncertaintyintoaccount,Kijko’smethodgivesthemaximumlikelihoodestimationofbvalueandannualactivityrate,whichmightbemorerealistic.Ontheotherhand,thismethodconsidersthesourcezoneboundaryuncertaintyinseismichazardanalysis,whichmeanstheearthquakeactivityrateacrossaboundaryofasourcezonechangessmoothlyinsteadofabruptlyandavoidstoolargeagradientinthecalculatedresults.

简介：ThevelocitystructureofthecrustbeneathLiaoningprovinceandtheBohaiseainChinawasimagedusingambientseismicnoiserecordedby73regionalbroadbandstations.Allavailablethree-componenttimeseriesfromthe12-monthspanbetweenJanuaryandDecember2013werecross-correlatedtoyieldempiricalGreen'sfunctionsforRayleighandLovewaves.PhasevelocitydispersioncurvesfortheRayleighwavesandtheLovewavesweremeasuredbyapplyingthefrequencytimeanalysismethod.DispersionmeasurementsoftheRayleighwaveandtheLovewavewerethenutilizedtoconstruct2Dphase-velocitymapsfortheRayleighwaveat8–35speriodsandtheLovewaveat9–32speriods,respectively.BothRayleighandLovephase-velocitymapsshowsignificantlateralvariationsthatarecorrelatedwellwithknowngeologicalfeaturesandtectonicsunitsinthestudyregion.Next,phasedispersioncurvesoftheRayleighwaveandtheLovewaveextractedfromeachcellofthe2DRayleighwaveandLovewavephase-velocitymaps,respectively,wereinvertedsimultaneouslytodeterminethe3Dshearwavevelocitystructures.ThehorizontalshearwavevelocityimagesclearlyandintuitivelyexhibitthattheearthquakeswarmsintheHaichengregionandtheTangshanregionaremainlyclusteredinthetransitionzonebetweenthelow-andhigh-velocityzonesintheuppercrust,coincidingwithfaultzones,andtheirdistributionisverycloselyassociatedwiththesefaults.Theverticalshearwavevelocityimagerevealsthatthelowercrustdownwardtotheuppermostmantleisfeaturedbydistinctlyhighvelocities,withevenahigh-velocitythinnerlayerexistingatthebottomofthelowercrustnearMohoincentralandnortherntheBohaiseaalongtheTanlufault,andthesephenomenacouldbecausedbytheintrusionofmantlematerial,indicatingtheTanlufaultcouldbejustastheuprisingchannelofdeepmaterials.

简介：WestudythefeatureofmediachangesbeneaththeZipingpureservoiranddiscusstheprocessofpermeationwiththewaterlevelriseandfallofthereservoirfromJanuary2005toJanuary2008fromambientnoisecrosscorrelationbyusingcontinuousseismicdatarecordedbythestationsofZipingpuseismicnetworkandYZPstation.Amoving-windowcross-spectrumtechniquehasbeenusedtocalculatetherelativeseismicvelocitychangesbetweenstationpairs.Resultsrevealedanobviousrelationshipbetweenrelativeseismicvelocity,andthewaterlevelchangeswithatimedelaythatmaybecausedbypermeationduringthreemainimpoundmentsandtwolargescaledisemboguements.Impoundmentgeneratesafastandlargeimpactonthesuperficiallayer,andthechangesofseismicvelocityistheresultofincreasedpressureandpermeationduringtheimpoundment.Atthefirstimpoundment,themaineffectfactorispressure.Duringthenexttwoprocessofimpoundment,permeationbecomesthemaineffectfactor,affectingthefaultatadepthofabout8km.

简介：Weappliedthedouble-differenceearthquakerelocationalgorithmto1348earthquakeswithM_S≥2.0thatoccurredinthenorthernTianshanregion,Xinjiang,fromApril1988toJune2003,usingatotalof28701P-andS-wavearrivaltimesrecordedby32seismicstationsinXinjiang.AimingtoobtainmostoftheseM_S≥2.0earthquakesrelocations,andconsideringtherequirementsoftheDDmethodandtheconditionofdata,weaddedthetraveltimedataofanother437earthquakeswith1.5≤M_S<2.0.Finally,weobtainedtherelocationresultsfor1253earthquakeswithM_S≥2.0,whichaccountfor93%ofallthe1348earthquakeswithM_S≥2.0andincludesalltheM_S≥3.0earthquakes.Thereasonfornotrelocatingthe95earthquakeswith2.0≤M_S<3.0isanalyzedinthepaper.Afterrelocation,theRMSresidualdecreasedfrom0.83sto0.14s,theaverageerroris0.993kminE-Wdirection,1.10kminN-Sdirection,and1.33kminverticaldirection.Thehypocenterdepthsaremoreconvergentthanbeforeanddistributedfrom5kmto35km,with94%beingfrom5kmto35km,68.2%from10kmto25km.Theaveragehypocenterdepthis19km.

简介：Inthispaper,wemadeasystematicstudyonmorethan40yearsofobservationaldataoftentemporaryfault-crossingmeasurementsitesinthecapitalcircleregionofChina.Wecalculatedhorizontalandvertica1componentsoffaultslip,andhorizontalextensionorcompressioncomponents.Consideringthetectoniccharacteristicsofthecapitalcircleregionandregionalseismicity,weanalyzedthepresentfaultactivityofthecapitalcircleregionandtherelationshipwithearthquakes.Theresultsshowthecomplexityoffaultactivityintheregion:thelevelofactivityofallfaultsislow,mostfaultsareleft-lateralstrike-slipfaults;thereislessverticalactivitythanhorizontalactivityandcrustalmovementiscontrolledbyhorizontalmovement;faultactivityandearthquakeactivityhaveacertainrelationship,regionalfaultactivityincreasesbeforeanearthquake,andfaultactivityhascertainabnormalfeaturesbeforestrongearthquakes.

简介：

简介：ＡｎａｌｙｓｉｓｏｆｆｕｔｕｒｅｓｅｉｓｍｉｃｉｔｙｏｆＪｉｎｇ－Ｊｉｎ－Ｔａｎｇｒｅｇｉｏｎａｎｄｓｅｖｅｎｍａｊｏｒｓｅｉｓｍｉｃｚｏｎｅｓ　ｗｉｔｈｔｈｅｅｘｔｒｅｍｅ－ｖａｌｕｅｔｈｅｏｒｙＲａｎＺＨＯＵ（周冉）ａｎｄＢａｎｇ－ＨｕｔＬＩＮ（...

简介：Weemployedadouble-differencealgorithm(hypoDD)torelocateearthquakeswithintheregionboundedby66°E-78°Eand32°N-42°Nintheperiodof1964?2003reportedbytheInternationalSeismologicalCenter(ISC).Theimprovedhypocentrallocationsdelineateadouble-layeredWadati-BenioffzoneintheeasternHinduKushintermediateseismicbelt.Basedonthisfeatureandotherevidences,weproposethattheintermediate-depthearthquakesbeneaththePamir-HinduKushregionmayoccurintwocollidedsubductionzoneswithoppositedipdirections.

简介：Basedonthefittingonpaleoearthquakedataofintra-plateregionsinthenorthernpartofChi-naandgivingastatisticalmodeloftimeinterdependence,thepotentialdamageearthquakesinadefinitefutureperiodandcharacteristicsofpresentshocksalongtheLingwufaulthavebeenanalyzedbyusingdangerousprobabilityfunctionandsomenewdataconcerned.Wehavein-ferredthatthefaulthasenteredaperiodthatearthquakeswillprobablyoccur.ThereexistsapotentialdangerthatastrongearthquakewithMs7.0-7.5willoccurin10-100a.

简介：

简介：Analysisofdeformationdatameasuredacrossthefaults,regionalverticaldeformationdataandGPSmeasurementsintheSichuan-Yunnanregionmadesincethe1980spermittedustoconcludethatthecrustaldeformationintheregionduringthisperiodoftimewasrelativelyweakandcausedtheoccurrenceofearthquakes(Ms≥6.0),whichwerenotdistributedalongthemajorboundaryactivefaultsintheregionafterthe1981DawuMs6.9earthquakeandthattheseismicactivityischaracterizedbyquasi-clockwisemigration.Thus,itfollowsthatearthquakepredictionresearchshouldbefocusedonthecentralpartoftheSichuan-Yunnanregioninthecomingyears.Finally,aconceptoftemporaldivisionoftheregionintoactiveblocksissuggestedandthepreliminaryresultofthedivisionisgiveninthepaper.

简介：TheprimarygoalofthedemonstrationprojectendorsedbytheScientificandTechnicalCommitteeforIDNDRin1992istoensurethatnationalagenciesareabletoassessseismichazardinaregionallycoordinatedfashionbyusingadvancedmethods.China,asaRegionalCenterofCentralSouthernAsia,hascontactedwithcountriesoftheregiontorealisticallypracticeseismichazardassessmentsofContinentalAsia.AtestarealocatedinthecollisionboundarybetweentheIndianandEurasianplateswaschosentoexaminetheseismichazardassessmentapproachintheregionalcoordinates.TheseismotectonicsandthreeversionsofseismicsourcesofthetestareaaredescribedinthispaperandundertheGlobalSeismicHazardAssessmentProgram(GSHAP),guidelinesanearthquakecatalogueofthetestareawasassembled.Becauseoftheincompletenessofearthquakedataindifferentcountries,weadoptdifferenttimewindowsfordifferentmagnitudeintervalsinordertoobtaintheseismicityparametersofsources.Byu

简介：Micro-aftershockswithmagnituderangeof1.5-4aroundtheWenchuanearthquakeepicenter,thesouthernpartoftheLongmenshanfaultzone,exhibitgoodfrequency-magnitudelinearrelationships,thusenablingb-valueanalysis.Theaverageb-valueformicro-aftershocksofM1.5-4fromJulytoDecemberof2008inourlocalstudyregionisabout0.88,similartotheb-valueforallaftershocksofM3.0-5.5fromMay,2008toMay,2009alongthewholeLongmenshanfaultzone.Thesimilaritybetweenthelocalandregionalb-valuespossiblyindicatesthatthesouthernpartoftheLongmenshanfaultzonehassimilarseismogenicenvironmenttothewholeLongmenshanfaultzone.Alternatively,itmayalsoimplythatb-valuesderivedfromalleventswithoutconsiderationofstructuralvariationcannotdiscriminatelocal-scaletectonicinformation.Thepresentstudyshowsthattheb-valuefortheWenchuanearthquakemicro-aftershocksvarieswithdifferentregions.Theb-valueinsouthwestoftheYingxiutownishigherthanthatinthenortheastoftheYingxiutown.Thehighb-valueinthesouthwestpartwheretheWenchuanearthquakemainshockhypocenterlocatedindicatesthatthecurrentstressaroundthehypocenterregionismuchlowerthanitssurroundingarea.Theb-valuesarealsodependentondepth.Atshallowdepthsof<5km,theb-valuesareverysmall(~0.4),possiblybeingrelatedtostrongwaveattenuationorstrongheterogeneityinshallowlayerswithhighcontentofporosityandfractures.Atdepthsof~5-11km,wheremostaftershocksconcentrated,theb-valuesbecomeashighas~0.9-1.0.Atthedepthbelow~11km,theb-valuesdecreasewiththedepthincreasing,beingconsistentwithincreasingtectonichomogeneityandincreasingstresswithdepth.

简介：