简介:Verticaltotalelectroncontent(VTEC)timeserieswereobtainedfrom22GPSstationsneartheepicenteroftheLushanearthquake.Inthispaper,wehaveadoptedaslidingaveragemethodtodetectandanalyzeanomalousVTECassociatedwiththeearthquake.Theresultsshowthatsignificant,negativeionosphereVTECanomaliesappearedoverthe5daysbeforetheearthquake,andonthedaywhenearthquakeoccurred.ThemaximumvalueofVTECanomaliesthatexceededthelowerboundreached20TECU.ThespatialdistributionofVTECanomaliesshowedaconjugatestructure,whichshiftedtothemagneticequator,andsubsequentlymovedwestwards.