简介:ThePearlRiverEstuary(PRE)islocatedattheonshore-offshoretransitionzonebetweenSouthChinaandSouthChinaSeaBasin,anditisofgreatsignificantvalueindiscussingtectonicrelationshipsbetweenSouthChinablockandSouthChinaSeablockandseismicactivitiesalongtheoffshoreactivefaultsinPRE.However,theresearchesongeometriccharacteristicsofoffshorefaultsinthisareaareextremelylacking.ToinvestigatetheoffshorefaultdistributionandtheirgeometricfeaturesinthePREingreaterdetail,weacquiredthirteenseismicreflectionprofilesin2015.Combiningtheanalysisoftheseismicreflectionandfree-airgravityanomalydata,thispaperrevealedthelocation,continuity,andgeometryofthelittoralfaultzoneandotheroffshorefaultsinPRE.ThelittoralfaultzoneiscomposedofthemajorDanganIslandsfaultandseveralparallel,high-angle,normalfaults,whichmainlytrendnortheasttonortheast-to-eastanddiptothesoutheastwithlargedisplacements.Thefaultzoneisdividedintothreedifferentsegmentsbythenorthwest-trendingfaults.Moreover,thebasementdeptharoundDanganIslandsisveryshallow,whileitsuddenlyincreasesalongtheislandswestwardandsouthward.Thesehasresultedintheislandsandneighboringareasbecomingtheplaceswherethestressaccumulateseasily.Theseismogenicpatternofthisareaiscloselyrelatedtothecomprehensiveeffectofintersectingfaultstogetherwiththelowvelocitylayer.
简介:Irregularsurfaceflattening,whichisbasedonaboundaryconforminggridandthetransformationbetweencurvilinearandCartesiancoordinatesystems,isamathematicalmethodthatcanelegantlyhandleirregularsurfaces,buthasbeenlimitedtoobtainingfirstarrivalsonly.Bycombiningamultistageschemewiththefast-sweepingmethod(FSM,themethodtoobtainfirst-arrivaltraveltimeincurvilinearcoordinates),thereflectedwavesfromacrustalinterfacecanbetracedinatopographicmodel,inwhichthereflectedwavefrontisobtainedbyreinitializingtraveltimesintheinterfaceforupwindbranches.Alocaltriangulationisappliedtomakeaconnectionbetweenvelocityandinterfacenodes.Thenajointinversionoffirst-arrivalandreflectiontraveltimesforimagingseismicvelocitystructuresincomplexterrainsispresented.Numericalexamplesallperformwellwithdifferentseismicvelocitymodels.Theincreasingtopographiccomplexityandevenuseofahighcurvaturereflectorinthesemodelsdemonstratethereliability,accuracyandrobustnessofthenewworkingscheme;checkerboardtestingillustratesthemethod’shighresolution.Noisetolerancetestingindicatesthemethod’sabilitytoyieldpracticaltraveltimetomography.Furtherdevelopmentofthemultistageschemewillallowotherlaterarrivalstobetracedandusedinthetraveltimeinversion.
简介:全极化SAR影像含有丰富的特征信息,针对单一特征用于分类难以达到满意精度的问题,提出一种基于不同目标分解方法及纹理信息的SVM(SupportVectorMachine,SVM)全极化SAR影像监督分类方法。结果表明,Cloude分解和Yamaguchi分解在极化特征信息提取时各有优势,且都优于Freeman分解效果;Cloude分解和Yamaguchi分解结合作为极化特征信息时,分类总体精度相对较高;纹理信息与极化特征信息在表现地物特性方面具有互补性,结合纹理信息后,分类总体精度提高了4.92%,为90.86%,Kappa系数为0.8754。