汶川8.0级地震同震重力与形变效应模拟

SIMULATION OF COSEISMIC GRAVITY CHANGES AND DEFORMATION EFFECT OF WENCHUAN Ms8.0 EARTHQUAKE

基于平面位错理论及已有的地震波反演结果,模拟了汶川Ms8.0地震产生的地表同震重力变化,并给出了地表同震水平和垂直位移。模拟结果表明:同震重力和形变变化显示出发震断层倾滑逆冲兼右旋走滑综合特征;同震重力变化明显,以发震断层为界呈正和负对称四象限分布图像,受地表垂直形变影响明显,近场区尤甚;远场重力变化一般在10×10-8ms-2以下,近场重力变化剧烈,最大可达50×10-8ms-2以上。模拟结果与实测结果基本一致。

According to the half-space dislocation theory and the fault models inversed by Institute of Geophysics, CEA and USGS, we calculated the surface coseismic gravity changes and displacements caused by the Wenchuan Ms8.0 earthquake, respectively. The simulated results show that 1 ） the characteristics of the dislocation are dip-slip and dextral strike slip ; 2） the distribution of coseismic gravity changes is with a pattern in four quadrants, which is, especially in the near-field controlled greatly by the distribution of vertical displacements; 3 ） the gravity change is usually less than 10 ×10^-8ms^-2in the far-field but up to several 100 ×10^-8ms^-2 in the near-field. Generally, the calculations agree with the observations well.