简介：13earthquakeswithM≥5.0havebeenrecordedinthenortheastregionofChinasince1970,amongwhicheightmedium-strongearthquakesareindependentinspaceandtime.Studiesofseismicitybeforetheseeightmedium-strongearthquakesshowthatsmallearthquakeactivitywasenhancedbeforetheoccurrences.ThoughseismicityincreaseisacommonphenomenoninthenortheastChinaregion,wehavedifficultyinpredictingthemedium-strongearthquakesbythisphenomenonalone.Inordertopredictmedium-strongearthquakesthroughseismicityincrease,thispapertriestoproposeanewmethodthatcalculatessmallearthquakefrequencythroughthechangingpatternofsmallearthquakeactivitiesbasedonthecharacteristicsofsmallearthquakeactivityinthenortheastChinaregion.Theresultsshowthatwecangettheobviousanomalyfrequencyofsmallearthquakesbeforemedium-strongearthquakesthroughthenewmethod,andcanobtainamediumtoshorttermanomalyindexforthenortheastChinaregion.

简介：

简介：P-waveandS-wavereceiverfunctionanalyseshavebeenperformedalongaprofileconsistedof27broadbandseismicstationstoimagethecrustalanduppermantlediscontinuitiesacrossNortheastChina.TheresultsshowthattheaverageMohodepthvariesfromabout37kmbeneaththeDaxing’anlingorogenicbeltinthewesttoabout33kmbeneaththeSongliaoBasin,andtoabout35kmbeneaththeChangbaimountainregionintheeast.OurresultsrevealthattheMohoisgenerallyflatbeneaththeDaxing’anlingregionandaremarkableMohooffset(about4km)existsbeneaththebasin-mountainboundary,theDaxing’anling-TaihangGravityLine.BeneaththeTanlufaultszone,whichseperatestheSongliaoBasinandChangbairegion,theMohoisupliftandthecrustalthicknesschangesrapidly.WeinterpretthisfeatureasthattheTanlufaultsmightdeeplypenetrateintotheuppermantle,andfacilitatethemantleupwellingalongthefaultsduringtheCenozoicera.Theaveragedepthofthelithosphereasthenosphereboundary(LAB)is*80kmalongtheprofilewhichisthinnerthananaveragethicknessofacontinentallithosphere.TheLABshowsanarc-likeshapeinthebasin,withtheshallowestpartapproximatelybeneaththecenterofthebasin.TheupliftLABbeneaththebasinmightberelatedtotheextensivelithosphericstretchingintheMesozoic.Inthemantletransitionzone,astructurallycomplicated660kmdiscontinuitywithamaximum35kmdepressionbeneaththeChangbairegionisobserved.The35kmdepressionisroughlycoincidentwiththelocationofthestagnantwesternpacificslabontopofthe660kmdiscontinuityrevealedbytherecentPwavetomography.

简介：Becauseofitsexcellentseismicperformance,reinforcedsoilretainingwallsareincreasinglyusedincivilengineering.Althoughmanycountrieshavepublishedcorrespondingdesigncodes,thedifferencesbetweenthemarestillrelativelylarge.UsingtheFHWACodeandtheCodeforSeismicDesignofRailwayEngineering(CSDRE),stabilitycalculationsofreinforcedsoilretainingwallswerecarriedoutandthesimilaritiesanddifferencesbetweenthesetwodesigncodeswereanalyzed.Accordingtothecomparativeanalysis,thefollowingconclusionsaredrawn:theinertiaforce,theearthpressureandthetensileforceofreinforcementscalculatedfromtheCSDREarelessthanthosefromtheFHWACode,andthesafetyfactorcalculatedfromtheformerislarger.AlthoughtheM-Omethodisrecommendedtocalculatethedynamicearthpressure,theFHWACodesuggestsahigheractionpointascomparedtotheCSDRE.

简介：ThecharacteristicsofseismicgroundmotionsinsouthernChinaaredifficulttodeterminestatisticallyduetoalackofstronggroundmotiondata.Inthisstudy,astochasticfinite-faultgroundmotionmodelwasadoptedtosimulatetheseismicgroundmotionsatbedrockforsouthernChina,basedonparametersderivedfromsmallandmediumearthquakesthathaveoccurredintheregion.Fromthese,theresponsespectrawasestimated.Asetofgroundmotionattenuationrelationshipswasthendevelopedbasedonsimulatedpeakgroundmotionsandresponsespectralparametersthroughregression,whichwouldbeapplicableforuseinengineeringpractice.Throughcomparisons,itwasdemonstratedthattheproposedgroundmotionrelationshipsaregenerallyconsistentwiththoseobtainedfromotherreportedgroundmotionattenuationmodelsforsouthernChina.

简介：At19:33p.monSeptember27,2003,anearthquakewithM7.9occurredintheRussiaMongolia-ChinaboundaryRegion.ItwasstronglyfeltintheAltayregionofXinjiang.Thelossescausedbytheearthquakewas76millionyuan(RMB).Someinformationabouttheearthquakewasoutlined,includingbasicparameters,focalmechanism,evaluationofearthquakedisasterlossesandsoon.Thesatelliteremotesensinginformationworkedinitialanalysisfordeformationofgroundandfailurephenomenon.

简介：ThenorthernLiulengshanpiedmontfaultislocatedalongthesouthernmarginoftheYangyuanbasinandrepresentsadip-slipnormalfault,generallyNEE-trendingandNNW-dipping.LandformsoffsetbythefaultarefairlydevelopedandwellpreservedintheDushanpuareaofYangyuanCounty,HebeiProvince.TwotrencheswereexcavatedinfrontofascarpofthenorthernLiulengshanpiedmontfaultatDushanpuandtwopaleoseismiceventswererevealedinthetrenches,fromwhichseveralsampleswerecollectedfordating.ThesamplesweredatedusingtheIRSLdatingtechnique.Thepreliminaryresultshowsthepossibleagesofthetwopaleoseismicevents.

简介：Studyofgeothermalfielddata,terrestrialheatflowvalues,andothergeophysicaldatafromtheXingtai-ShuluareaofHebeiProvincemadeusmoreunderstandingofthedistributionofgeothermalfieldsanddeepstructuresandtheirinterrelation.Thestudyillustratesthatthegeothermalfieldhasanapparentlateralinhomogeneityandisevidentlycorrelatedbythestructureofthecrustanduppermantleinthearea.Therelationofthegeothermalfielddistributiontothestructureindicatesthatincomparisonwiththedepressionzone,theupliftzonehasahigherheatflowvalueandalargergeothermalgradient.Theanalysisoftherelationbetweendistributionofearthquakeepicentersandgeothermalfieldandmathematicalsimulationofthermalstressintheareasuggeststhatthermalstressplaysanimportantroleintheprocessofearthquakegeneration.

简介：MomenttensorsolutionswereretrievedfortheearthquakeswarmthatoccurredduringNovemberandDecember2010intheBoshanminingarea,ShandongProvince,China.Theresultsshowedthatthedouble-couplecomponentsinthesourcemechanismswerehigheratthebeginningoftheswarmandconsistedmainlyofshearfaultingcontrolledbytectonicstress.Thesubsequenteventshadsignificantnon-double-couplecomponents,indicatingtensilefaulting.Thedouble-couplecomponentspredominatelypresentedasnormalfaultingandthePaxeswereorientatedalmostvertically.Theslipvectorsoftheswarmeventswererelativelystable.Withreferencetothetectonicfeaturesneartheepicenter,weconcludedthattheswarmwasaresultofsubordinatefaultmotionrelatedtotheWangmuMountainfaultandthathigh-pressureporefluidsplayedacrucialroleintheactivityoftheearthquakeswarm.

简介：Basedonthecasestudiesandstatisticalanalysisofearthquake-relatedionosphericdisturbancesmainlyfromDEMETERsatellite,ground-basedGPSandionosoundingdata,thispapersummarizesthestatisticalcharacteristicsofearthquake-relatedionosphericdisturbances,includingelectromagneticemissions,plasmaperturbationsandvariationofenergeticparticleflux.AccordingtothemainresultsdonebyChinesescientists,fusingwiththeexistedstudyfromglobalresearches,seismo-ionosphericdisturbancesusuallyoccurredafewdaysorhoursbeforeearthquakeoccurrence.Parallelingtothesecasestudies,lithosphere-atmosphere-ionosphere(LAI)couplingmechanismsarecheckedandoptimized.Athermo-electricmodelwasproposedtoexplaintheseismo-electromagneticeffectsbeforeearthquakes.Apropagationmodelwasputforwardtoexplaintheelectromagneticwavesintotheionosphere.Accordingtotherequirementofearthquakepredictionresearch,Chinaseismo-electromagneticsatellite,thefirstspace-basedplatformofChineseearthquakestereoscopicobservationsystem,isproposedandplannedtolaunchatabouttheendof2014.ItfocusesoncheckingtheLAImodelanddistinguishingearthquake-relatedionosphericdisturbance.ThepreliminarydesignforthesatellitewilladoptCAST-2000platformwitheightpayloadsonboard.Itisbelievedthatthesatellitewillworktogetherwiththegroundmonitoringnetworktoimprovethecapabilitytocaptureseismo-electromagneticinformation,whichisbeneficialforearthquakemonitoringandpredictionresearches.

简介：

简介：ThispaperreportstheinternalstructuresoftheBeichuanfaultzoneofLongmenshanfaultsystemthatcausedthe2008Wenchuanearthquake,atanoutcropinHongkou,Sichuanprovince,China.PresentworkisapartofcomprehensiveprojectofInstituteofGeology,ChinaEarthquakeAdministration,tryingtounderstanddeformationprocessesinLongmenshanfaultzonesandeventuallytoreproduceWenchuanearthquakebymodelingbasedonmeasuredmechanicalandtransportproperties.Outcropstudiescouldbeintegratedwiththoseperformedonsamplesrecoveredfromfaultzonedrilling,duringtheWenchuanEarthquakeFaultScientificDrilling(WFSD)Project,tounderstandalong-faultanddepthvariationoffaultzoneproperties.Thehangingwallsideofthefaultzoneconsistsofweakly-foliated,clayeyfaultgougeofabout1minwidthandofseveralfaultbrecciazonesof30-40mintotalwidth.Wecouldnotfindanypseudotachyliteatthisoutcrop.DisplacementduringtheWenchuanearthquakeishighlylocalizedwithinthefaultgougelayeralongnarrowerslipping-zonesofabout10to20mminwidth.Thisisanimportantconstraintforanalyzingthermalpressurization,animportantdynamicweakeningmechanismoffaults.Overlappingpatternsofstriationsonslickensidesurfacesuggestthatseismicslipatagiventimeoccurredinevennarrowerzoneofafewtoseveralmillimeters,sothatlocalizationofdeformationmusthaveoccurredwithinaslippingzoneduringcoseismicfaultmotion.Faultbrecciazonesareboundedbythinblackgougelayerscontainingamorphouscarbon.Faultgougecontainsilliteandchloriteminerals,butnotsmectite.Clayeyfaultgougenexttocoseismicslippingzonealsocontainsamorphouscarbonandsmallamountsofgraphite.ThestructuralobservationsandmineralogicaldataobtainedfromoutcropexposuresofthefaultzoneoftheWenchuanearthquakecanbecomparedwiththoseobtainedfromtheWFSD-1andWFSD-2boreholes,whichhavebeendrilledveryclosetotheHongkououtcrop.Thepresenceofcarbonandgr

简介：

简介：Becauseseismicactivitywithinmid-continentsisusuallymuchlowerthanthatalongplateboundaryzones,evensmallearthquakescancausewidespreadconcerns,especiallywhentheseeventsoccurinthesourceregionsofpreviouslargeearthquakes.However,thesesmallearthquakesmaybejustaftershocksthatcontinuefordecadesorevenlonger.TherecentseismicityintheTangshanregioninNorthChinaislikelyaftershocksofthe1976GreatTangshanearthquake.ThecurrentearthquakesequenceintheNewMadridseismiczoneincentralUnitedStates,whichincludesaclusterofM*7.0eventsin1811–1812andanumberofsimilareventsinthepastmillennium,isbelievedtoresultfromrecentfaultreactivationthatreleasespre-storedstrainenergyinthecrust.Ifso,thisearthquakesequenceissimilartoaftershocksinthattheratesofenergyreleaseshoulddecaywithtimeandthesequenceofearthquakeswilleventuallyend.WeusesimplephysicalanalysisandnumericalsimulationstoshowthatthecurrentsequenceoflargeearthquakesintheNewMadridfaultzoneislikelyendingorhasended.Recognizingthatmid-continentalearthquakeshavelongaftershocksequencesandcomplexspatiotemporaloccurrencesarecriticaltoimprovehazardassessments.

简介：OnApril25,2015,aM_S8.1earthquakeoccurredinNepal.IntheTibetareaofChina,thisearthquakecausedheavycasualtiesanddamagetohousing,roads,communications,otherlifelineengineering,waterconservancyandotherinfrastructure.Thispaperintroducesthebasicsituationoftheearthquake,andbasedontheinvestigationandassessmentofseismicintensity,thedamageofthedisasterareaisanalyzed,andbuildingtypesanddamagetothelifelinesystemsandvariousindustriesaregiven.Throughtheanalysisofthecharacteristicsoftheearthquakedisaster,thispaperpointsouttheexistingproblemsinseismicfortification,andfinallyputsforwardproposalsforthepreventionandcontrolofearthquakegeologicaldisasters,scientificplanningfortherestorationandreconstruction,strengtheningearthquakepreventionanddisasterreductionpropaganda,improvingtheawarenessofearthquakepreparednessintheagriculturalandpastoralareas,strengtheningtheguidanceandsupervisionofhousingconstructioninruralareastoreducethecasualtiesandlosses,andpromotingtheharmoniousdevelopmentofeconomyinTibet.

简介：Ontheconditionthatthevelocityratioofcompressivewavetoshearwaveisstableduringthepropagatingprocessofseismicwave,thispaperdevelopsanestimationmethodformediumqualityfactorbasedonsinglestation'straveltimedifferencebetweendirectSandPwavesandthefirstperiodsignalofdirectPwave.8774highSNRwavedataaltogetherrecordedby75stationsareanalyzed.Theresultsshowthat:(1)underthenormalregionalstressfield,thequalityfactorsQmSPinthestabletectonicareaarehigherthanthatintheactivetectonicareaaroundtheWeifang-JiashansectionanditssurroundingareaintheTanlufaultzone;(2)intheJuxian-Tanchengsectiontheseismicwaveattenuationisrelativelyquick,andthemediaisrelativelybroken,suggestingnotectonicstressaccumulation;(3)theXinyi-Sihongsectioniscurrentlylockingandinaccumulatingelasticstrainenergystage,whichhasthedeepenvironmentandconditionsofstrongearthquakegenerationsimilartothoseofthe1668M8.5Tanchengstrongearthquake.

简介：ＰｒｅｌｉｍｉｎａｒｙｒｅｓｕｌｔｓｏｎｋｉｎｅｍａｔｉｃｍｏｄｅｌｏｆｔｅｃｔｏｎｉｃｂｌｏｃｋｓｄｅｒｉｖｅｄｆｒｏｍｈｉｇｈｐｒｅｃｉｓｉｏｎＧＰＳｏｂｓｅｒｖａｔｉｏｎｓｉｎＳｏｕｔｈｗｅｓｔＣｈｉｎａＬＩＲＥＮＨＵＡＮＧ１）（黄立人）...

简介：Buisomg126earthquakefocalmechanismsolutions(Ms≥4.7)duringtheperiodof1963-1998,moderntectonicstressfieldinNorthChinaisinvertedbymeansofthestepbystepconv-ergence.Theinversionresultsindicatethatthetectonicstressfieldintheresearchregionisclearlyvariationalinspaceandtime:(1)Themiddlingprincipalstressaxisó2isbasicallyver-tical.Themaximumandminimumprincipalstressaxesó1andó2arenearlyhorizontal,buttheazimuthsofó1andó3areinconsistentindifferentdistrictsandperiods.(2)BeforetheTangshanearthquakein1976,thethreeprincipalstressaxesareuniform.Theazimuthofmaximumprincipalstressaxisó1is68°(strikinginaNEE-SWWdirection).(3)AftertheTangshanearthquake,themaximumprincipalstressaxisó1andminimumprincipalstressaxisó3havevariationsindifferentdistricts.InthenorthernareaofNorthChinaandontheeasternsideoftheTancheng-Lujiangfaultzone,themaximumprincipalstressaxisó1isalsostrikinginaNEE-SWWdirection.Itsazimuthis68°.ItistheasmeasthatbeforetheTangshanearth-quake.InthesouthernareaofNorthChina,themaximumprincipalstressaxisó1isstrikinginaE-Wdirectionanditsazimuthis87°.

简介：Ｃｒａｃｋ－ｉｎｄｕｃｅｄａｎｉｓｏｔｒｏｐｙｉｎｔｈｅｃｒｕｓｔｆｒｏｍｓｈｅａｒｗａｖｅｓｐｌｉｔｔｉｎｇｏｂｓｅｒｖｅｄｉｎＴａｎｇｓｈａｎｒｅｇｉｏｎ，ＮｏｒｔｈＣｈｉｎａＹｕａｎＧＡＯ（高原）Ｓｉ－ＨｕａＺＨＥＮＧ；（郑斯华）ａｎｄＹｏｎｇ...

简介：Onthebasisoflocatingbythegeochemicalprospecting,shallowseismicsounding,drilling,geologicalprofiling,andneogeochronologicaldating,wefirstfoundoutthedislocationamountalongtheLiaocheng-LankaoburiedfaultsincetheQuaternaryandtheageofitslatestactivityphaseanddeterminedthattheupperbreakpointbythefaultdislocationreaches20mbelowthesurface.ThelatestactivityphasewasintheearlyHoloceneandthefaultisashallow-buriedactivefault.Anaveragedislocationratealongthefaultis0.12mm/asincetheQuaternary.Thus,itisaburiedactivefaultwithintermediatetostrongmovementstrengthintheeasternChina.