BasedontheseismicobservationreportdataprovidedbytheXinjiangDigitalSeismicNetworkfrom2009to2014,wecalculatethewavevelocityratioanditsbackgroundvalueformediumandsmallearthquakesbyusingthemulti-stationmethodinTianshan,Xinjiang.Thispaperanalyzesthevariationofthewavevelocityratiodisturbancevaluetohighlighttheabnormal,andalsoback-traces7moderateearthquakesattheresearcharea.Theresultsshowthat:(1)thebackgroundvalueofthewavevelocityratioisalmost1.70,thewavevelocityratioobviouslydecreasesinthemiddle-easternpartofTianshanandtheregionnearthePuchangfault;(2)thewavevelocityratiodisturbancevalueismostlylowintheepicenterbeforefourearthquakesofM≥5.0from2011to2013inthestudyarea;(3)before7moderatestrongearthquakes,theearthquakeeventswithlowvalueofthewavevelocityratioaccountforover60%ofcorrespondingtotaleventsneartheepicenters,andthelowvalueofthewavevelocityratioisrelativelyobviousbeforemoderateearthquakes.
