基于干涉雷达的玉树地震断裂运动模式与地震迁移趋势分析

2010年4月14日青海省玉树县发生M_s7.1级地震。利用地震前后2期ALOS雷达数据进行了地表同震形变场InSAR解译研究，获取了高质量的干涉图像，并解算出定量变形场。进而根据干涉计算的变形方向、变形范围、变形量和变形梯度，参考该区的构造背景和走滑断裂的力学机理对本次地震构造活动进行了分析并得出如下结论：1）玉树地震引发了地表NWW走向、由5段构成的“S”形走滑断裂，总体为左阶排列，走滑量从10.2 cm到133.2 cm不等，走滑极值可达195 cm，其中在结古镇和隆宝镇附近的两段出现较明显的地表破裂；2）断裂两侧的雷达视线向运动方向和运动量的差异预示发震断裂以左旋走滑运动为主，SW盘为主动盘；3）宏观震中可以定位于玉树县城西北约16 km的地表陡变带附近；4）发震断裂地表行迹、变形量和地表破裂幅度预示余震将主要沿发震断裂向NW迁移；5）根据青藏高原东部地块的分区，本次地震属于羌塘地块活动的结果，与巴颜喀拉地块活动引发的汶川地震不存在直接的关联。

Analysis of Geoseismic Faults Movement and Aftershocks Migration for Yushu Earthquake Based on InSAR Co-Seismic Deformation

On April 14,2010,a Ms7.1 earthquake struck the Yushu County,Qinghai Province,China.The authors observed the co-seismic deformation of Yushu Ms7.1 scale earthquake,on July,14,2010,using two periods PALSAR by Interferometric Synthetic Aperture Radar(InSAR) technology,and yielding a clearly wrapped InSAR image and solving a absolutely deformation map covering most earthquake impact region.Furthermore,referencing to the amount,region,direction and gradient of InSAR co-seismic deformation,as well as combining with tectonic setting and mechanics of strike-slip fault,this paper infers its tectonic activity features: 1)Yushu earthquake triggered a NWW extend,sinistral step,"S" shape strike-slip fault deformation belt,which contains 5 sub-sections,average slip dislocation ranging from 10.2 cm to 133.2 cm,maximum up to 195 cm,and two of them near Jiegu Town and Longbao Town presented clear surface ruptures.2)The difference of two walls’ movement in direction and amount shows that the seisgenic fault is a sinistral strike-slip and SW wall is an initiative wall.3)The macro-epicenter can be located on mutation belt of NW 16 km of Yushu County;4)The deformation amount,surface track and rupture amplitude of seisgenic fault indicate that the aftershocks will migrate towards NW alone fault.5)This earthquake is the results of Qiangtang Block’s activity and does not directly related with Wenchuan Earthquake induced by Bayan Har Block.