2010青海玉树地震同震重力和形变效应模拟

SIMULATION OF COSEISMIC GRACITY CHANGE AND DEFORMATION FOR 2010 QINGHAI YUSHU EARTHQUAKE

分别以远场地震波形和In SAR数据反演得到的玉树地震断层滑动模型为基础,使用PSGRN/PSCMP程序计算了黏弹分层介质中玉树Ms7.1地震产生的同震重力和形变场。结果表明:1)由远场地震波形数据得到的断层滑动模型计算的同震重力和位移变化与震后野外调查得到的形变场更符合;2)可以监测到的同震重力变化仅分布在断层附近,同震水平位移影响范围明显大于同震重力变化影响范围;3)震前两年和震后一个月,在玉树绝对重力台观测到的绝对重力变化与由两个断层模型计算的结果有明显差别,表明观测到的绝对重力变化蕴含着地震孕育过程、同震重力变化和震后恢复过程产生的重力变化。

Coseismic gravity change and deformation in layer viscoelastic medium caused by Yushu MsT. 1 were calculated using PSGRN/PSCMP based on different fault slip models. The results show that ： 1 ） Coseismic grav- ity change and displacement calculated for teleseimic waveform based on the fault slip model are more consistent with results from field survey;2）Coseismic gravity change only locates near by faults, and the range influenced by coseismic horizon displacements are obvious widely than that by coseimic gravity change;3 ）The obsolute gravity change during the period of two years before the earthquake and one month after the earthquake is obvious different from the result calculated,which indicats that observed obsolute gravity change implies earthquake preparation and coseismic change and post-seismic change.