简介:SeveralearthquakeswithMs≥5.0occurredintheDatongseismicregionin1989,1991and1999,TheprecisefocuslocationoftheearthquakesequencewasmadebytherecordsoftheremotesensingseismicstationnetworkinDatong.Usingthatdatatogetherwithmacro-intensitydistributionandfocalmechanismsolutions,weanalyzethedifferenceamongthreesubsequences.Theresultsshowthatthefocalfaultofthe1999Ms5.6earthquakewasaNWW-trendingleft-lateralstrike-slipfault.Itis16kmlongand12kmwide.Itdevelopedatthedepthof5kmandisnearlyverticalindip.Thetwopreviousearthquakesubsequences,however,weregeneratedbyactivityalongNNE-trendingright-lateralstrike-slipfault.Itcanbefoundthattherupturedirectioinofthe1999earthquakehaschanged.Itisgenerallyfoundthatarupturezonehasmorethantwodirectionsandhasdifferentstrengthalongthesetwodirections.Thecomplicatedegreeoffocalcircumstanceisrelatedtothetypeofearthquakesequences.ThereistheNE-trendingDawangcunfaultandtheNW-trendingTuanbufaultintheseismicregion,butnoproofindicatesaconnectionbetweenfocalfaultsandthesetwotectonicfaults.Thefeaturethatfocalfaultsofthreesubsequencesarestrike-slipisdifferentfromthatofthetwotectonicfaults.Itissuggestedthatthe1999earthquakesubsequencewaspossiblygeneratedbyanewrupture.
简介:Usingthe78focalmechanismsolutionsoftheforeshocks,mainshockandaftershocksoftheearthquakesequencefortheYao'anearthquake,thecharacteristicsofthefocalfaultsandstressfieldfortheearthquakesequenceareanalyzed.TheresultsshowthatthemainruptureplaneoftheYao'anearthquakesequenceisatectonicfaultwithN50°Wstrikeandsteepdipandallthemainshock,theforeshocksandthevastmajorityofaftershocksoccurredonthemainruptureplane.AtectonicfracturewithNNE-NEstrikealsoparticipatedindevelopmentprocessofthesequencedominatedbyprincipalcompressionalstresswithnearlyhorizontalorientationSSEisconsistentwiththeregionaltectonicstressfield.Inthesequencedevelopment,thestressfieldinthefocalregionwascomplexwithmultiaximuthsandmulti-actionmodelsandthefocalruptureshowedcomplexfeatureswithmulti-directionsandmulti-patterns.
简介:TheRedRiverFaultZoneisagiganticslide-slipfaultzoneextendingupto1000kmfromTibettoSouthChinaSea.Ithasbeendividedintothenorth,centralandsouthsegmentsaccordingtothedifferenceofthegeometry,kinetics,andseismicityontheland,butaccordingtothecontactedrelationshipbetweentheoldpre-CenozoicblockinIndochinaPeninsulaandtheSouthChinablock,theRedRiverFaultZonewasdividedintotwopartsextendingfromlandtoocean,thenorthandsouthsegments.SincetheTertiary,theRedRiverFaultZonesufferedfirstthesinistralmovementandthenthedextralmovement.Theactivitiesofthenorthandthesouthsegmentsweredifferent.Basedontheanalysisofearthquakesandfocalmechanismsolutions,earthquakeswiththefocusdepthsof0-33kmaredistributedoverthewholeregionandmoredeepearthquakesaredistributedonthenortheasternsidesoftheRedRiverfault.Typesoffaultingactivitiesarethethrustinthenorthwest,thenormalinthenorthandthestrike-slipinthesouth,withtheoddtype,viz.thetransitiontype,intheotherregion.TheseshowtheRedRiverFaultZoneanditsadjacentregionsufferedtheextrudingforceinNNWdirectionandthenormalstressinNEEdirectionanditmakesthefaultintheregionextrude-thrust,horizontalstrike-slipandextensionalnormalmovement.
简介:Complex time-space spreading and focal mechanism of the 1989 Batang earthquake swarm (M_s=6.7)(程万正)(陈天长)Complextime-spacespre...
简介:Basedonwaveformdata,severalmethodstodeterminefocalmechanismsofsmallearthquakesweredevelopedsince1980.Kisslinger(1980)andJulian,Foulger(1996)proposedanapproachtodeterminesolutionbyusingamplituderatioofPandSwave.Schwartz(1995)devisedamethodtodeterminesolutionsbytheuseofpolaritydataandamplitudesofseismogramenvelopes.Amplitudesofshortperiodseismicwavespropagatinginaninhomogene-ousmediumaresensitivetothevariationinvelocityandQstructure.Nakamura,etal(1999)tookmediuminhomo-geneityintoaccountindeterminingfocalmechanismsofsmallearthquakesusingwaveformdata.Ifthelocationsofsmallearthquakesareconcentratedinasmallregion,wecanassumethattheraypathsfromtheeventstoagivenstationarealmostthesame.SoPandSwaveattenuationsareindependentofeventlocations.Inthiscaseitiscon-venienttodeterminefocalmechanismsoftheseeventsbyusingshortperiodPandSwavedataj.Focalmechanismsolutionsofsmallearthquakesin5regions,i.e.,Rongchang,Mabian-Muchuan,Ya¢an,BaoxingandMianzhu,whicharecoveredbytheChengduTelemeteredNetwork,areobtainedbyanalyzingthePpolarityandshortbodywaveamplitudedatarecordedinthenetworksince1992.AccordingtothemethodproposedbyGephartandForsyth(1984),basedonwelldeterminedfocalmechanismsolutionsin15sub-zonesofSichuanandYunnanarea,threeprincipalstresstensorss1,s2,ands3,insteadofaveragesofP,B,andTaxisofthesolutions,aredeterminedtorepresenttheregionalstressfielddistribution.
简介:AIMProstaglandinA1(PGA1)isacyclopentenoneprostaglandin.Recently,wereportedthatPGA1caninhibitexcitotoxin-inducedapoptosisofstriatalneuronsinvivoandrotenone-inducedapoptosisofculturedSH-SY5Ycells,suggestingthatPGA1mayhaveneuroprotectiveefficacy,possiblymediatedbyinhibitionofNF-kBactivation.ThepresentstudyevaluatedtheneuroprotectivepotentialofPGA1anditseffectonIKK/I(B/NF-kB/c-mycsignalingpathwayinratmodelsofpermanentfocalcerebralischemia.METHODSPermanentmiddlecerebralarteryocclusion(pMCAO)modelwasconstructedbyintraluminalsuturecannulationthroughtheinternalcarotidarteryinWistarrats.