简介:At12:07UT(8:07pmChinaStandardTime)on2017Oct4,abrightbolidewaswidelyobservedintheShangri-LaregionoftheProvinceofYunnan,China(Figure1).TheeventwaswellobservedbythegeneralpublicasittookplaceonthenightoftheMidAutumnFestival,whichisassociatedwithmoongazing.SonicboomsandgroundshakingwerereportedinanareaofaboutathousandsquarekilometersnorthwestofShangri-LaCity.DatafromU.S.governmentsensorssuggeststhattheimpactenergyoftheeventwasapproximately0.54ktTNTequivalent,withtheterminusofthebolidepositionedat28.1°N,99.4°E.ThisisthelargestobservedbolideeventoverlandsincethebolideeventthattookplaceinMauritaniaon2016Jun27(1.2kt).
简介:IntheSoutheastMarginoftheTibetanPlateau,low-velocitysedimentarylayersthatwouldsignificantlyaffecttheaccuracyoftheH-κstackingofreceiverfunctionsarewidelydistributed.Inthisstudy,weuseteleseismicwaveformdataof475eventsfrom97temporarybroadbandseismometersdeployedbyChinArrayPhaseItoobtaincrustalthicknessesandPoisson’sratioswithintheChuxiong-SimaoBasinandadjacentarea,employinganimprovedmethodinwhichthereceiverfunctionsareprocessedthrougharesonance-removalfilter,andtheH-κstackingistime-corrected.Resultsshowthatthecrustalthicknessrangesfrom30to55kminthestudyarea,reachingitsthickestvalueinthenorthwestandthinningtowardsouthwest,southeastandnortheast.TheapparentvariationofcrustalthicknessaroundtheRedRiverFaultsupportstheviewofsoutheasternescapeoftheTibetanPlateau.RelativelythincrustalthicknessinthezonebetweenChuxiongCityandtheRedRiverFaultindicatespossibleupliftofmantleinthisarea.ThepositivecorrelationbetweencrustalthicknessandPoisson’sratioislikelytoberelatedtolowercrustthickening.Comparisonofresultsobtainedfromdifferentmethodsshowsthattheimprovedmethodusedinourstudycaneffectivelyremovethereverberationeffectofsedimentarylayers.