简介：1SURVEYOFGLOBESEISMICITYIN2007Atotalof22strongearthquakeswithM_S≥7.0occurredintheworldaccordingtotheChineseSeismicStationNetworkin2007(Table1).ThestrongestearthquakewastheSouthernSumatraearthquakewithM_S8.5onSeptember12(Fig.1).Earthquakefrequencyin2007washigherthanin2006,andenergyreleaseincreasedremarkablycomparedwiththatin2006.Therearethefollowingcharacteristics:

简介：1SURVEYOFGLOBALSEISMICITYIN2011Atotalof26strongearthquakeswithMS≥7.0occurredin2011throughouttheworldaccordingtotheChinaSeismicNetwork(Table1).ThestrongestearthquakewastheJapanearthquakemeasuringMS9.0onMarch11(Fig.1).Thefrequencywasslightlylowerandthe

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简介：1SURVEYOFGLOBALSEISMICITYIN2013Atotalof23strongearthquakeswithMS≥7.0occurredin2013throughouttheworldaccordingtotheChinaSeismicNetwork(Table1).ThestrongestearthquakewasintheSeaofOkhotsk,measuringMS8.2onMay24(Fig.1).Earthquakesoccurredmainlyinthewesternpartofthecircum-Pacificseismicbelt.Comparedwiththeseismicityin2012,thefrequencyincreasedsignificantlyandtheenergyreleaseofearthquakeswasobviouslylow.FeaturesofglobalseismicityofMS≥7.0areasfollows:

简介：1.SURVEYOFGLOBESEISMICITYIN2004Atotalof19strongearthquakeswithMs≥7.0occurredintheworldaccordingtotheChineseSeismicStationNetworkin2004(Table1).ThestrongestearthquakewastheSumatraearthquakewithMs8.7nearthenorthwestcoastofSumatraonDecember26(Fig.1).Globalseismicitymaintainsthesamepatternsfromrecentyears,beingdistributedmainlyonthewesternpartofthecircum-Pacificseismiczone.RemarkablemacroseismicactivitieswereseenintheIndia-AustralianplateandintheJapanregion.ThemacroseismicactivitiesofMs≥7.0in2004wereasfollows:

简介：1SURVEYOFGLOBALSEISMICITYIN2012Atotalof20strongearthquakeswithMS≥7.0occurredin2012throughouttheworldaccordingtotheChinaSeismicNetwork(Table1).Thestrongestearthquakewasoffshore,inthenorthcoastofSumatra,measuringM8.6andM8.2onApril11(Fig.1).Comparedwiththe

简介：Inthispaper,researchofaftershockmechanismsisreviewed,includingheterogeneityofmediumandstress,mechanicalloading,fluidintrusionandstresscorrosion,andratestatedependence.Previousstudieshaveindicatedthattheheterogeneityofmediaandstressisthebasicpremiseofaftershocksgenerated.Fromthepointviewofmechanics,transientcreepandafterslipcanexplainthedecayofaftershocksinashorttimeafteramainshockandtherelaxationofstresstendstointerpretthecharacteristicsoflong-termaftershocks.Fluidintrusionandstresscorrosioncontroltheevolutionprocessoftheaftershocksundercertainconditions.Theinteractionbetweenthefaultsperturbedbythemainshockalwaysexistsduringtheaftershockactivities.Allkindsofmodelsandthetheorieswanttocomplywiththetwobasicpower-lawrelationships---theG-RlawandOmorilawtosomeextent.

简介：Researchoftidaltriggeringofearthquakesinrecentyearsissystematicallyreviewed,focusingontherelationshipbetweenthephasesofthemoonandseismicactivity,earthquakestriggeredbytidalforcesanditscomponents,basedonthelargesamplestatisticstodiscussthetidaltriggeringofanearthquake.Therelationshipbetweenthephaseofthemoonandseismicactivityisapreliminarystudyoftidaltriggeringofearthquakes,andthemodulationratioisaquantitativedescriptionofit.Usingtheresolutionoftidalstresstostudyseismicactivityisawaytorevealtherelationshipbetweenthetidesandearthquakesfromthemechanicspointofview.Largesamplestatisticsisanotherwaytostudytherelationshipbetweenthetidalandearthquakefromtheviewofstatistics.Inmanystatisticalmethods,Schuster'stestisusedmorewidely,whichtakesmanyfactorsintoaccount,suchasfocalmechanism,tidalstress,andstatisticalteststoquantitativelyanalyzethetidaltriggeringeffectonearthquakes.

简介：Thispaperreviewsbrieflytheprogressesmadeduringthelastfouryears(1999～2002)instudyofseismotectonicsinChina,especiallyappraisestheachievementsinthefieldsofthecrustalanduppermantle'sstructure,theactivefaultsandtectonicsettingoflargeearthquakes,thecrustaldeformation,andthenumericalsimulation.MostearthquakesoccurredinChinabelongtocontinentalearthquakes.Therefore,Chineseseismologistspaymoreattentiontothecontinentalearthquakes.BasedonimprovementsoftheobservationsystemsinChinaduringtheninthFive-YearPlan,thestudiesonseismotectonicshaveachievedgreatprogresses.

简介：ThestatusofdeepgeophysicalexplorationandresearchinChinaissummarizedinthispaper.Newachievementsinthestudyofthevelocitystructure,seismotectonicsandgeodynamicsofthecrustanduppermantlearealsobrieflydescibed.

简介：Thispaperreviewedthemaintarget,functions,tool(OpenQuakesoftware)andresearchachievementsoftheGlobalEarthquakeModel(GEM)Foundation,andmadeasimpleprospectonthedevelopmentandapplicationofprojectsofGEMinthefuture.LearningfromGEMandOpenQuakeishelpfultoimprovetheseismichazardmodelofChinaandenhancethescientificityoftheseismichazardassessmentformetropolitansandmajorengineeringfacilitiesnearmajorseismogenicstructures.

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简介：InthearticletheauthorlooksbacktheharddevelopmentcourseandgreatprogressinearthquakescienceandtechnologyinChinaduringthelastnearahalfofcenturyandexpoundsthefollowing3aspects:(1)Thestrongdesireofthewholesocietytomitigateseismicdisastersandreducetheeffectofearthquakesonsocial-economicliveisagreatdrivingforcetopushforwardthedevelopmentofearthquakescienceandtechnologyinChina;(2)Tobetterensurepeople'slifeandproperty,sustainableeconomicdevelopment,andsocialstabilityisanessentialpurposetodrivethedevelopmentofearthquakescienceandtechnologyinChina;and(3)Toinsistonthedialecticalconnectionofsetupoftechnicalsystemforseismicmonitoringwiththescientificresearchofearthquakesandtobetterhandletherelationbetweencrucialtask,currentscientificlevel,andthefeasibilityaretheimportantprinciplestoadvancetheearthquakescienceandtechnologyinChina.Somesuccessandmanysetbacksinearthquakedisastermitigationconsistentlyenrichourknowledgeregardingthecomplexityoftheconditionsforearthquakeoccurrenceandtheprocessofearthquakepreparation,promotethereconstructionandmodernizationoftechnicalsystemforearthquakemonitoring,anddeepenthescientificresearchofearthquakes.Duringthelast5years,theimprovementandmodernizationoftechnicalsystemforearthquakemonitoringhaveclearlyprovidedthetechnicalsupporttostudyandpracticeofearthquakepredictionandprecaution,giveprominencetokeyproblemsandbroadenthefieldofscientificresearchofearthquakes.Thesehaveenabledustogetsomenewrecognitionoftheconditionsforearthquakeoccurrenceandprocessofearthquakepreparation,characteristicsofseismicdisaster,andmechanismforearthquakegenerationinChina'scontinent.Theprogresswehavemadenotonlyencouragesustoenhancetheeffectivenessofearthquakedisastermitigation,butalsoprovidesabasisforacceleratingfurtherdevelo

简介：Monitoringofsubsurfacefluid(undergroundfluid)isanimportantpartofeffortsforearthquakepredictioninChina.Thenationwidenetwork,whichmonitorsgroundwaterlevel,watertemperature,andradonandmercuryingroundwater,hasbeenconstructedinthelastdecades.Largeamountsofabnormalfluidchangesbeforeandaftermajorearthquakeshavebeenrecorded,providingpreciousdataforresearchinearthquakesciences.Manystudieshavebeendoneinearthquakefluidhydrogeologyinordertoprobethenatureoftheearthquake.Muchprogressinearthquakefluidhydrogeologyhasbeenmadeinthelastdecades.Thepaperprovidesareviewoftheadvancesinresearchonearthquakefluidhydrogeologyoverthelast40yearsinChina.Itdealswiththefollowingfiveaspects:(1)anintroductiontothedevelopmenthistoryofmonitoringnetworksconstruction;(2)casesofdifferentsubsurfacefluidchangesrecordedbeforesomemajorearthquakeswhichoccurredinthelastdecades;(3)characteristicsofsubsurfacefluidchangesfollowingmajorearthquakes;(4)mechanismofsubsurfacefluidchangesbeforeandfollowingearthquakes;(5)applicationofearthquakefluidsinthehydrogeologyfield.

简介：Crustalfaultsusuallyhaveafaultcoreandsurroundingregionsofbrittledamage,formingalow-velocityzone(LVZ)intheimmediatevicinityofthemainslipinterface.TheLVZmayamplifygroundmotion,influencerupturepropagation,andholdimportantinformationofearthquakephysics.Anumberofgeophysicalandgeodeticmethodshavebeendevelopedtoderivehigh-resolutionstructureoftheLVZ.Here,Ireviewafewrecentapproaches,includingambientnoisecross-correlationondenseacross-faultarraysandGPSrecordingsoffault-zonetrappedwaves.Despitethepastefforts,manyquestionsconcerningtheLVZstructureremainunclear,suchasthedepthextentoftheLVZ.High-qualitydatafromlargeranddenserarraysandnewseismicimagingtechniqueusinglargerportionofrecordedwaveforms,whicharecurrentlyunderactivedevelopment,maybeabletobetterresolvetheLVZstructure.Inaddition,effectsofthealongstrikesegmentationandgradationalvelocitychangesacrosstheboundariesbetweentheLVZandthehostrockonrupturepropagationshouldbeinvestigatedbyconductingcomprehensivenumericalexperiments.Furthermore,high-qualityactivesourcessuchasrecentlydevelopedlarge-volumeairgunarraysprovideapowerfultooltocontinuouslymonitortemporalchangesoffault-zoneproperties,andthuscanadvanceourunderstandingoffaultzoneevolution.

简介：The2018PaluMW7.5earthquakeandtsunamiattractedgeophysicists'attentionforitsstrikeslipfocalmechanismandmagnitude.Weinspectedthedetailsofthisdisasteranddiscusseditsparticularityandpossiblecausations.Thesubmarinelandslideandspecialterrainconditionscouldhavecontributedtotheunusualsizeofthetsunami.Theearlywarningsystemandthepostdisasterresponseisalsoreviewed.Efficientsocialwarningsandbroadcastsystemsalongwithgoodmaintenanceisessential.Wealsofoundthatenhancingpublicsscientificliteracyisthemostimportantwaytoreducedisasterdamageandcasualties.Moreover,socialconditionsandrebuildingdifficultiesposttsunamiarerelatedasreferenceresourcesforfuturedisastermanagementstrategies.

简介：Basedontheprincipleformulaforthefour-componentstrainmeters,wecandirectlyobtainthespecificplanestrain,shearstrainandazimuthalangleoftheprincipalstrain,andthemaximumandminimumprincipalstrainscalculatedafterwardsaretheindirectresult.TheproblemsofpracticalityofthesensitivitycoefficientsAandBofplanestrainandshearstrainarethendiscussed.Basedonthisidea,weanalyzedtheobservationdataofseveralfourcomponentboreholestrainmetersneartheepicenteroftheYiliangMS5.7earthquakein2012andtheLudianMS6.5earthquakein2014intheZhaotongarea,YunnanProvince.Theresultsshowthattheanalysisbasedontheperspectiveofplanestrainandshearstrainhasanobviouslybettereffectthanthatbasedonthecomponentreadings,andcandirectlypeelofftherespectiveabnormalityoftheplanestrainandshearstrain.Inaddition,thecorrelationcoefficientcurvesbetweenmeasureddataoftwoplanestrainsshowsignificantanomalieswhichoftenoccurseveraldaysbeforeandduringtheearthquake.

简介：TheDeepSeismicSounding(DSS)projectscarriedoutfromthe1970sinthelowerYangtzeregionanditsneighboringareawerereviewedinthispaper,thenthebasicwavegroupfeaturesofthosewideanglereflection/refractionrecordsections,andofthecrustalstructurearesummarized.Itshowsthattherewereintotalfiveclearwavegroupsontherecordsections,whichincludethefirstarrivalPg,thereflectionP1fromthebottominterfaceoftheuppercrust,thereflectionP3fromthebottominterfaceofthemiddlecrust,thestrongreflectionPmfromtheMohoboundary,andtherefractionPnfromuppermostmantle.Ingeneral,thesephasesareeasilyconsistentlytracedandcompared,despitesomefirstarrivalsbeingdelayedorarrivingearlierthannormalduetotheshallowsedimentarycoverorbedrocks.Inparticular,intheDabieMountainregiontheseismiceventsofafewgatheredshotsalwayshaveweakreflectionenergy,aretwisted,orexhibitdisorganizedwaveforms,whichcouldbeattributedtothedisruptionvariationsofreflectiondepth,thebrokenMoho,andthediscontinuityofthereflectionboundarywithincrust.Theregionalcrustalstructuresarecomposedoftheupper,middleandlowercrust,ofwhichthemiddleandlowerlayerscanbedividedintotwoweakreflectionones.ThecrustalthicknessoftheNorthChinaandYangtzeplatformare30km-36km,andtheMohoexhibitsaflatgeometrydespitesomelocaluplifts.Theaveragepressurevelocityinlowercrustbeneaththistwotectonicareais6.7±0.3km/s.Nevertheless,beneaththeDabieshanareathecrustalthicknessis32km-41km,theMohobendsdownsharplyandtakesanabrupt4km-7kmdislocationintheverticaldirection.TheaveragepressurevelocityinthelowercrustbeneaththeDabieshanareais6.8±0.2km/s.