基于梯度下降法反演于田Mw7.1地震同震滑动分布

COSEISMIC SLIP DISTRIBUTION OF YUTIAN Mw7.1 EARTHQUAKE BASED ON STEEPEST DESCEND METHOD

利用InSAR技术与ENVISAT ASAR雷达数据,获取了2008年3月21日于田7.1级地震同震形变场;结合野外考察优化了于田地震三分段破裂模型;并基于梯度下降法反演获得了于田地震的同震破裂模式与深部滑动特征。结果表明:滑动分布集中位于断层面0～14 km深部,最大滑动量位于中段F2深部2.05 km处,为5.47 m;北段F1为左旋与正断基本相当的倾滑破裂,而中段F2、南段F3-N/F3-S以正断为主、兼具一定左旋走滑分量;滑动量主要集中在中段与南段,北段滑动量较小,反演获得的地震矩Mo=5.16×1019N.m,相当于矩震级7.07级。

Using InSAR technology and the ENVISAT ASAR data, this paper obtains the coseismic deforma- tion fields of Yutian Mw 7.1 earthquake happened on March 21,2008. This paper inverts the coseismic slip distri- bution of Yutian earthquake with the Steepest Descent Method （SDM）. The results are shown as follows. The inver- sion residual errors of the ascending and descending orbit surface deformation field are effectively controlled to small value ; the major slip distribution is concentratedly located from 0 to 14 km depth along the fault plane ; The largest slip value is about 5.47 m which is located in depth of 2.05 km along the fault plane of F2 ; the northern section of F1 is the oblique-slip rupture nearly equal to left lateral strike-slip and dip-slip, while the middle section of F2 and southern section of F3-N/F3-S are basically the dip-slip rupture with a little of left lateral strike-slip; The slip is mainly concentrated in the middle and southern section, and the slip of the northern section is small, the total seis- mic moment M0 from inversion is about 5.16 × 10^19 Nm, equivalent to moment magnitude Mw7.07.