Usingthedouble-differencerelocationalgorithm,werelocatedthe20April2013Lushan,Sichuan,earthquake(MS7.0),andits4,567aftershocksrecordedduringtheperiodbetween20AprilandMay3,2013.Ourresultsshowedthatmostaftershocksarerelocatedbetween10and20kmdepths,butsomelargeaftershockswererelocatedaround30kmdepthandsmalleventsextendedupwardnearthesurface.Verticalcrosssectionsillustrateashovel-shapedfaultplanewithavariabledipanglefromthesouthwesttonortheastalongthefault.Furthermore,thedipangleofthefaultplaneissmalleraroundthemainshockthanthatinthesurroundingareasalongthefault.Theseresultssuggestthatitmaybeeasytogeneratethestrongearthquakeintheplacehavingasmalldipangleofthefault,whichissomewhatsimilartothegenesisofthe2008Wenchuanearthquake.TheLushanmainshockisunderlainbytheseismicallyanomalouslayerswithlow-VP,low-VS,andhigh-Poisson’sratioanomalies,possiblysuggestingthatthefluid-filledfracturedrockmatricesmightsignificantlyreducetheeffectivenormalstressonthefaultplanetobringthebrittlefailure.TheseismicgapbetweenLushanandWenchuanaftershocksissuspectedtobevulnerabletofutureseismicrisksatgreaterdepths,ifany.
