玉树地震地表变形InSAR观测及初步分析

D-INSAR OBSERVATION OF EARTH SURFACE DEFORMATION IN THE MS_7.1 YUSHU EARTHQUAKE

采用玉树MS7.1级地震前后两期PALSAR雷达数据(震前2010年1月15日,震后4月17日)进行了"两轨+DEM"的InSAR处理,获得了高质量的差分干涉雷达条纹图像和同震变形场。参考该区的基本构造格局,根据干涉图像的变形范围、变形量和变形梯度可以初步判断:(1)玉树地震诱发了总体上NWW走向,全长约70km地表陡变带,陡变带南段位错及陡变梯度较大,会在地表产生地表破裂;而西北部4段位错及陡变梯度较小,不易在地表诱发破裂,但可能在地下一定层位产生了隐伏破裂带;(2)陡变带两侧的雷达视线向运动方向预示发震断裂以左旋走滑运动为主;(3)宏观震中位于玉树县城西北约16km的地表陡变带上。D-InSAR解译结果与中国地震台网中心震源机制解、野外发震断裂调查结果及地貌特征吻合较好,证明了干涉雷达解译成果的可靠性,可以为准确定位玉树地震发震断裂地表行迹和快速评定震害损失提供有力的技术支持。

A ＂Two Paths ＋ DEM＂interferometric process was made for the PALSAR SAR data before（Jan.15,2010） and after（Apr.17,2010） the Yushu MS7.1 Earthquake,which yielded a high-quality co-seismic InSAR strip image and absolutely surface deformation.Based on the deformation scale,deformation magnitude and deformation gradient,in combination with tectonic setting of the area,the following conclusions can be drawn：（1） Yushu earthquake triggered a 70-km NWW-extending mutation belt,with a southern section Showing greater dislocation and deformation gradient,which will induce surface raptures,and No.4 segment in northwestern part showing weaker deformation and no ruptures on the ground surface.（2） The SAR motive directions from both sides of mutation belt indicate a dominant sinistral movement of seisgenic faults.（3） The macro-epicenter is located on the mutation belt 16km northwest of Yushu County.The present InSAR interpretations match well with the seismic mechanics,field investigations and geomorphology features from the China Earthquake Networks Center,and can provide better support for rapid evaluation to earthquake hazard and accurately ing surface track of seismogenic fault.