玉树M_S 7.1级地震前的形变应变场变化特征  

The variation of the deformation-strain field before M_s7.1 Yushu earthquake

作　　者：郭良迁[1] 薄万举[1] 杨国华[1] 胡新康[1] 郭赫[1] 陈长云[1] 

机构地区：[1]中国地震局第一监测中心,天津300180

出　　处：《地球物理学报》2011年第8期1990-1996,共7页Chinese Journal of Geophysics

基　　金：天津市应用基础研究(08JCZDJC18900);中国地震局"全国地震区划图编制项目"资助

摘　　要：基于1999～2007年和2007～2009年的GPS站点观测数据计算的速度场,分析了青藏亚板块的运动特征.利用块体(旋转与线性应变)弹性运动公式计算可可西里—巴颜喀拉块体和羌唐块体的应变率、可可西里—玉树断裂带的运动速度和应变率,研究了玉树7.1级地震前的形变应变特征.结果表明:可可西里—巴颜喀拉块体处于青藏亚板块运动场的差异变化较大的地带;1999～2007年可可西里—玉树断裂带左旋走滑运动为主;2007～2009年可可西里—玉树断裂带在玉树以西压应变率显著增强,利于应力积累,以东为右旋为主,玉树附近地段成为不同应变应力状态的转换地带——不稳定地段.可可西里—玉树断裂带的活动为7.1级地震孕育提供了能量积累和发震条件.t Base on the velocity field calculated from the GPS data from 1999 to 2007 and from 2007 to 2009,the movement characteristics of Qinghai-Tibet subplates were studied. The strain rate of Hob Xil-Bayan Har block and the Qiangtang block, the velocity and the strain rate of Hob Xil-Yushu fault zone were calculated by the block （rotation and linear stain） elastic movement formula. The deformation strain before Ms7. 1 Yushu earthquake has been studied. The result shows that between 1999 and 2007 the activity in Yushu fault zone was mostly left-lateral strike slip. Between 2007 and 2009, the strain rate of Hoh Xil-Yushu fault zone in the western part of Yushu has increased remarkably, which is favorable to stress accumulation. The Hoh Xil-Yushu fault zone in the eastern part of Yushu showed mainly right-lateral strike slip activity. Yushu was a transitional area between different kinds of active strain and became an unstable zone. The activity in Hob Xil-Yushu fault zone became a condition of the Ms7.1 earthquake, in the meantime,accumulated energy for the earthquake.

关 键 词：GPS运动场 块体运动 断裂带活动 应变率增加 玉树地震孕育 

分 类 号：P553[天文地球—构造地质学]