Analysis of Seismic Activity Characteristics before the Yutian MS7.3 Earthquake, Xinjiang on February 12, 2014

(整期优先)网络出版时间:2014-04-14
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Thispaperintroducesthegeologicalstructurebackgroundaroundthe2014YutianM_S7.3earthquakearea,investigatesandanalyzestheregimeofsmallearthquakeactivityandthecharacteristicsofregionalseismicitypatterninXinjiangbeforetheearthquake,andcomparesthecharacteristicsoftheregionalseismicactivitywiththe2008YutianM_S7.3earthquake.Theresultsshow:12~3yearsbeforethe2014YutianM_S7.3earthquake,Xinjiangwasinaseismicactivestatewithstrongearthquakeoccurringsuccessively,andbeforethe2008M_S7.3earthquake,Xinjiangwasinthequietstateofmoderate-smallearthquakeswithM3.0~4.0.2BeforethisYutianM_S7.3earthquake,theregionalseismicactivityshowedashort-termanomalyfeature,thatis,seismicityofM≥5.0earthquakessignificantlyincreasedontheAltunseismiczoneandinthesourceareathreeyearsbeforetheM_S7.3earthquake,whileafiveyearlongquiescenceofseismicityofM≥4.0earthquakesappearedontheeastofthesourceareainarangeofabout440km.SixmonthsbeforethisM7.3earthquake,thereexistedseismicgapofM3.0~4.0earthquakesandnear-conjugateseismicbeltmagnitude3.0and4.0inthesourcearea.3ThestateofstrongearthquakeactivityandtheseismicitypatternofsmallearthquakesbeforethisYutianM_S7.3earthquakeweresignificantlydifferenttothatbeforethe2008YutianM_S7.3earthquake,andthismayberelatedtothedifferentseismogenicenvironmentsofthetwoM_S7.3earthquakes.