汶川地震前后川滇块体应变与断裂变形特征研究

STUDY ON CHARACTERISTICS OF BLOCK STRAIN AND FAULTS DEFORMATION OF SICHUAN-YUNNAN REGION BEFORE AND AFTER WENCHAUN EARTHQUAKE

利用1999—2007和2007—2009年GPS资料,采用块体变形模型和GPS速度剖面研究了川滇地区的分阶段变形特征,结果显示川西北-滇中-滇西南块体主压应变率方向由北向南呈顺时针方向旋转;安宁河断裂、则木河断裂存在剪切应变积累,小江断裂南段以走滑为主、北段以应变积累为主;汶川地震对丽江-小金河断裂中南段、安宁河断裂和金沙江断裂有一定影响,对则木河断裂、小江断裂和红河断裂的影响较小。

Using the GPS velocity field data during the periods of 1999—2007 and 2007—2009,we analyzed the deformation characteristics of the Sichuan-Yunnan region during the two periods with block deformation model and by analyzing the GPS velocity profiles.The results show that the direction of the principal compressive strain rate of the west-northern segment of Sichuan block-the middle segment of Yunnan block-the west-southern segment of Yunnan block is characterized by clockwise rotation from north to south.The Anninghe fault and the Zemuhe fault have some shear strain accumulation,and the southern segment of Xiaojiang fault is mainly strike-slip,but its northern segment is mainly accumulating strain.The earthquake had relatively obvious influence on the medium-southern segment of Lijiang-Xiaojinhe fault,the Anninghe fault and the Jinshajiang fault,meanwhile it affected the Zemuhe fault,the Xiaojiang fault and the Honghe fault less.