简介：Weanalyzed360permanentandcampaignGPSdatafrom1999to2017inthesouthernSichuan-Yunanblock,andobtainedcrustalhorizontaldeformationinthisregion.Then,wederivedthestrainrateusingamulti-scalesphericalwaveletmethod.ResultsrevealacomplexpatternoftectonicmovementinthesouthernSichuan-Yunnanblock.ComparedtothestableEurasianplate,themaximumrateofthehorizontaldeformationinthesouthernSichuan-Yunnanblockisapproximately22mm/a.TheXiaojiangfaultshowsasignificantlylowerdeformation—aleft-lateralstrike-slipmovementof9.5mm/a.TheHonghefaultclearlyshowsacomplexsegmentaldeformationfromthenorthtosouth.ThenorthernHonghefaultshows4.3mm/arightstrike-slipwith6.7mm/aextension;thesouthernHonghefaultshows1.9mm/arightstrike-slipwith1.9mm/aextension;thejunctionzoneintheHongheandLijiang–Xiaojinhefaultsshowsanobviousclockwise-rotationdeformation.Thestraincalculationresultsrevealthatthemaximumshear-strainrateinthisregionreaches70nstrain/a,concentratedaroundtheXiaojiangfaultandatthejunctionoftheHongheandLijiang–Xiaojinhefaults.Wenotethatmostoftheearthquakeswithmagnitudesof4andabovethatoccurredinthisregionwerewithinthehighshearstrain-ratezonesandthestrainrategradientboundaryzone,whichindicatesthatthemagnitudeofstrainaccumulationiscloselyrelatedtotheseismicactivities.Comparisonofthefastshear-wavepolarizationdirectionoftheupper-crustwiththeupper-mantleanisotropyandthedirectionofthesurfaceprincipalcompressivestrainrateobtainedfromtheinversionoftheGPSdatarevealsthatthedirectionofthesurfaceprincipalcompressivestrainisbasicallyconsistentwiththefastshear-wavepolarizationdirectionoftheuppercrustanisotropy,butdifferentfromthepolarizationdirectionoftheuppermantle.OurresultssupportthehypothesisthattheprincipalelementsofthedeformationmechanisminthesouthernSichuan-Yunnanblockaredeco

简介：ThelinkbetweenthecrustaldeformationandmantlekinematicsintheTibetanPlateauhasbeenwellknownthankstodenseGPSmeasurementsandtherelativelydetailedanisotropystructureofthelithosphericmantle.However,whetherthecrustdeformscoherentlywiththeuppermantleintheShan-Thaiterrane(alsoknownastheShan-Thaiblock)remainsunclear.Inthisstudy,weinvestigatethedeformationpatternsthroughstrainratetensorsinthesoutheasternTibetanPlateauderivedfromthelatestGPSmeasurementsandfindthatintheShan-Thaiterranetheuppercrustmaybecoupledwiththelowercrustandtheuppermantle.TheGPS-derivedstrainratetensorsareinagreementwiththeslippingpatternsandratesofmajorstrike-slipfaultsintheregion.Themostprominentshearzone,whoseshearstrainratesarelargerthan100×10^–9a^–1,isabout1000-km-longinthewest,trendingnorthwardalongSagaingfaulttotheEasternHimalayanSyntaxisinthenorth,withmaximumrateofcompressivestrainupto–240×10^–9a^–1.AsecondaryshearzonealongtheAnninghe-XiaojiangFaultintheeastshowssegmentedshearzonesnearseveralconjunctions.WhilethestrainratealongRRFisrelativelylowduetothelowsliprateandlowseismicitythere,inLijiangandTengchongseverallocalshearzonesarepresentunderanextensionaldominatedstressregimethatisrelatedtonormalfaultingearthquakesandvolcanism,respectively.Furthermore,bycomparingGPS-derivedstrainratetensorswithearthquakefocalmechanisms,wefindthat75.8%(100outof132)oftheearthquakeT-axesareconsistentwiththeGPS-derivedstrainrates.Moreover,wefindthattheFastVelocityDirection(FVDs)atthreedepthsbeneaththeShan-Thaiterraneareconsistentwithextensionalstrainratewithgraduallyincreasingangulardifferences,whicharelikelyresultingfromthebasalshearforcesinducedbyasthenosphericflowassociatedwiththeobliquesubductionoftheIndiaplatebeneaththeShan-Thaiterrane.Therefore,inthisregiontheuppercrustd

简介：DataobtainedbyGRACE(GravityRecoveryandClimateExperiment)havebeenusedtoinvertfortheseismicsourceparametersofmegathrustearthquakesundertheassumptionofeitheruniformslipoveranentirefaultorapoint-likeseismicsource.Herein,wefurtherextendtheinversionofGRACElong-wavelengthgravitychangestoheterogeneousslipdistributionsduringthe2011Tohokuearthquakeusingthreefaultmodels:(I)aconstant-strikeandconstant-dipfault,(II)avariabledipfault,and(III)arealisticallyvaryingstrikefault.Byremovingthepost-seismicsignalfromthetimeseries,andtakingtheeffectofoceanwaterredistributionintoaccount,weinvertforslipmodelsI,II,andIIIusingco-seismicgravitychangesmeasuredbyGRACE,de-stripedbyDDK3decorrelationfilter.Thetotalseismicmomentsofourslipmodels,withrespectivevaluesof4.9×1022Nm,5.1×1022Nm,and5.0×1022Nm,aresmallerthanthoseobtainedbyotherstudiesrelyingonGRACEdata.Theresultingcentroidsarealsolocatedatgreaterdepths(20km,19.8km,and17.4km,respectively).BycombiningonshoreGPS,GPS-Acoustic,andGRACEdata,weobtainajointlyinvertedslipmodelwithaseismicmomentof4.8×1022Nm,whichislargerthantheseismicmomentobtainedusingonlytheGPSdisplacements.Weshowthattheslipinvertedfromlowdegreespace-bornegravimetricdata,whichcontainsinformationattheoceanregion,isaffectedbythestrikeofthearcuatetrench.Thespace-bornegravimetricdatahelpusconstrainthesourceparametersofamegathrustearthquakewithintheframeofheterogeneousslipmodels.