2008年10月西藏当雄M_W6.3地震震后形变提取与余滑反演  

Postseismic deformation extraction and afterslip inversion of the October 2008 Damxung M_W6.3 earthquake

作　　者：洪顺英[1] 董彦芳[1] 孟国杰[1] 张奎[2] 陈立泽[1] HONG ShunYing;DONG YanFang;MENG GuoJie;ZHANG Kui;CHEN LiZe(Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China;Chongqing University,Chongqing 400044,China)

机构地区：[1]中国地震局地震预测研究所,北京100036 [2]重庆大学,重庆400044

出　　处：《地球物理学报》2018年第12期4827-4837,共11页Chinese Journal of Geophysics

基　　金：国家重点研发计划项目(2017YFB0502700);国家自然科学基金(41604062;41461164004;41304002;41174004);中国地震局地震预测研究所基本科研业务专项(2017IES010102;2018IEF010103)共同资助

摘　　要：2008年10月6日西藏当雄发生M_W6.3地震.本文利用震后2008年10月26日至2010年8月22日的16期ENVISAT ASAR数据,通过小基线集干涉测量、误差校正与MInTS(Multiscale InSAR Time Series)技术提取高精度的震后形变场,利用SDM(Steepest Descent Method)方法反演断层震后余滑演化过程,并分析震后余滑与同震滑动的关系.结果表明:当雄M_W6.3地震的近场震后形变场主要位于断层西侧,在时间演化上具有明显的对数函数衰减规律;震后余滑主要集中于断层中南段深0～15km区间,最大的余滑量约0.07m,位于断层深约9.28km处,滑动角约-103°;震后余滑引起的地震矩能量M_0与矩震级MW在时间演化上具有指数函数递增规律;当剪切模量μ=32GPa,震后665天余滑释放的地震矩能量约为1.92×10^(17) N·m,约占同震滑动释放地震矩的4.8%,相当于矩震级M_W5.46;虽然震后余滑已经延伸到断层浅部0～5km区间,但由于余滑量相对较小,没有改变同震滑动在断层浅部区域的滑动亏损现象,这可能是2010年11月30日该区域又发生M_W5.3级余震的主要原因之一.On October 6 th,2008,an M W6.3 earthquake occurred in Damxung,Tibet.Based on 16 scenes of ENVISAT ASAR images acquired during October 26 th 2008 to August 22 th 2010,this paper employed the techniques of the small baseline interferometry,error correction,and MInTS(Multiscale InSAR Time Series)to extract the high-precision post-seismic deformation field.The fault after-slip evolution process was inverted using SDM(Steepest Descent Method).The relationship between the co-seismic slip and after-slip along the fault was analyzed.The results show that the post-seismic deformation field is mainly located at the west of fault with an obvious logarithmic function attenuation over time.The afterslip mainly concentrate at a depth of 0~15 km in the middle and south part of the fault,and the maximum after-slip is about 0.07 m,which is located at a depth about 9.28 km with a slip angle about-103°.The seismic moment energy(M 0)and seismic moment tensor(M W)caused by afterslip increased exponentially over time.When the shear modulusμ=32 GPa,the post-seismic moment energy in 665 days is about 1.92×10 17 N·m,which is approximately 4.8%of the co-seismic moment energy,and is equivalent to M W5.46.Although the after-slip extended to a shallow depth of 0~5 km along the fault,it didn′t change the sliding deficit caused by the coseismic slip because the afterslip is relatively small.It may be one of the major factors for the occurrence of the subsequent M W5.3 aftershock at the same region on November 30 th 2010.

关 键 词：当雄地震 余滑 INSAR MInTS SDM 

分 类 号：P313[天文地球—固体地球物理学]