摘要
Inordertostudythespatiotemporalevolutionoftheprecursoryanomalies10yearsbeforetheWenchuanMS8.0earthquakein2008,theepicentraldistanceoftheprecursoryanomaliesiscalculatedbyusingthegeometriccenteroftheruptureregionandtheellipticalcenterlineoftheaftershockregion.Theresultshows,precursoranomaliesgraduallyincreasedabout2yearsbeforetheWenchuanearthquake.Theratioofabnormalitemsisgreaterthan25%inthenearsourcearea(abouttwicethesourcescale)and17%-24%intheremotearea(about3-5timesthesourcescale).Therearethreedifferentstagesofspatiotemporalevolutionofprecursoryanomalies.Duringtheαstage(includingα1andα2,between700to3000daysbeforethemainearthquake),theanomaliesaremainlydistributedinthesouthwestandnorthwestareaoftheWenchuanaftershocksarea.Itisshownthattheprecursorsofthefarsourceregionandthenearsourceareahavethecharacteristicsofoutwardexpansion.Duringtheβstage(between300to700daysbeforethemainearthquake),theanomaliesaredistributedinthesouthwestandnorthernregionoftheaftershockregion,showingalargerangeofanomalies.Duringtheγstage(includingγ1andγ2,300daysbeforethemainearthquake),therangeofanomalydistributioniswide,andtheanomaliesaredistributedinthesouthwestandnortheastoftheaftershockarea.Theanomaliesconvergedtoepicenter(γ1)inthefarsourceregionandexpandoutwards(γ2)inthenearsourceregion.Resultsoftheexperimentalstudyandmechanicalanalysisofearthquakepreparationprocessindicatethatthethree-stagecharacteristicsofprecursoryanomaliesintheprocessofearthquakepreparationmaybecontrolledbytheseismogenicbody,whichisaformofexpressionintheprocessofearthquakepreparationandauniversalfeatureduringtheearthquakepreparationprocess,whichhasacertainguidingroleinearthquakeprediction.
出版日期
2018年02月12日(中国期刊网平台首次上网日期,不代表论文的发表时间)