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简介：Usingfoursatellitedatasets(TOMS/SBUV,OMI,MLS,andHALOE),weanalyzetheseasonalvariationsofthetotalcolumnozone(TCO)anditszonaldeviation(TCO*),andrevealtheverticalstructureoftheOzoneLow(OV)overtheAsiancontinent.Ourprincipalfindingsare:(1)TheTCOovertheAsiancontinentreachesitsmaximuminthespringanditsminimumintheautumn.TheOzoneLowexistsfromMaytoSeptember.(2)TheOzoneLowhastwonegativecores,locatedinthelowerandtheupperstratosphere.Thelowercoreisnear30hPainthewinterand70hPaintheotherseasons.Theuppercorevariesfrom10hPato1hPaamongthefourseasons.(3)ThepositionoftheOzoneLowinthelowerandtheupperstratosphereovertheAsiancontinentshowsseasonalvariability.

简介：TheGarouaZoneinNorthCameroon,thesubjectofthisstudy,isknowntohaveundergonetectonicmovementsduringtheCretaceous,butthezone’sstructuraldataremainpoorlyknown.ThisstudyexploitstheBougueranomalytoimproveknowledgeofGarouatectonicsstructures.Inordertocharacterizethesestructures,twomethodsareused:Euler’sdeconvolutionmethodandthemethodofthehorizontalgradientoftheverticalderivative.SuperpositionoftheEuler’ssolutionsmapforindexN=1withthemapfromthehorizontalgradientoftheverticalderivativemethodallowsdeterminationofgravimetriclineaments,interpretedasfaultsoraslinearcontacts,fromwhichwededuceastructuralmapofthestudyarea.Basedonthismap,weidentifysixteenlineaments,ofwhichwecounteightaslinearcontactsandeightasfaults.Amongthefaults,wedenoteoneofdepthbetween4and8km,fivefaultsofdepthrangingbetween8and13km,andtwofaultsofdepthsbetween13and36km.Analysisofthesefaultsshowsthatthesevendeepestfaultsmightpresentanaturalriskinourstudyarea.Forpurposesofcivilprotection,suchdeepfaultsshouldbemonitoredandtakenintoconsiderationintheimplementationoflargepublicworks.Thestructuralmap,establishedhereinfromdataonthein-depthextensionofeachfault,thusincreasesscientificknowledgeintheareathatcanbeusedtositepublicworksinwaysthatreducerisk.

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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：OnNovember13,2016,anMW7.8earthquakestruckKaikourainSouthIslandofNewZealand.Bymeansofback-projectionofarrayrecordings,ASTFs-analysisofglobalseismicrecordings,andjointinversionofglobalseismicdataandco-seismicInSARdata,weinvestigatedcomplexityoftheearthquakesource.Theresultshowsthatthe2016MW7.8Kaikouraearthquakerupturedabout100sunilaterallyfromsouthtonortheast(~N28°–33°E),producingaruptureareaabout160kmlongandabout50kmwideandreleasingscalarmoment1.01×1021Nm.Inparticular,theruptureareaconsistedoftwoslipasperities,withoneclosetotheinitialrupturepointhavingamaximalslipvalue~6.9mwhiletheotherfarawayinthenortheasthavingamaximalslipvalue~9.3m.Thefirstasperityslippedforabout65sandthesecondonestarted40safterthefirstonehadinitiated.Thetwoslippedsimultaneouslyforabout25s.Furthermore,thefirsthadanearlythrustslipwhilethesecondhadboththrustandstrikeslip.Itisinterestingthattherupturevelocitywasnotconstant,andthewholeprocessmaybedividedinto5stagesinwhichthevelocitieswereestimatedtobe1.4km/s,0km/s,2.1km/s,0km/sand1.1km/s,respectively.Thehigh-frequencysourcesdistributednearlyalongtheloweredgeoftherupturearea,thehighfrequencyradiatingmainlyoccurredatlaunchingoftheasperities,anditseemedthatnohigh-frequencyenergywasradiatedwhentherupturingwasgoingtostop.

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.

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