2012年苏门答腊MW8.6级地震震后效应模拟

基于弹性-粘弹性分层半空间中矩形位错理论和地震波反演的断层模型，结合研究区地壳-上地幔平均波速分层结构，利用PSGRN/PSCMP软件模拟计算2012年苏门答腊MW8.6地震产生的同震效应以及考虑2004年MW9.1地震效应的震后地表形变和重力变化，同时给出震后形变和重力的年变化率。结果表明，同震形变和重力变化显示发震断层左旋走滑特征，其变化主要集中于断层附近；海水质量的重新分布对同震垂直位移和重力变化影响显著；震后50 a年均变化率揭示了地表形变和重力变化的过程, 其图像明显受2004年MW9.1地震震后效应影响，呈现复杂的正负6区域分布；震后50 a近场年均形变量达10 mm/a，年均重力变化量达1.2 μGal/a，而远场年均形变量低于1 mm/a，年均重力变化量低于0.1 μGal /a；水平形变在震后400 a内变化明显，变化率逐步减小，800 a后基本稳定；垂直位移和重力变化在震后100 a内变化尤为显著，变化率快速衰减，400 a后基本稳定不变。

Post-Seismic Effect Simulation of the Sumatra MW8.6 Earthquake

Based on the theory of rectangular dislocation and the seismic wave inversion in the elastic-viscoelastic stratified half-space, combined with the average velocity of the crust-upper mantle in the study area, PSGRN/PSCMP software is used to simulate the 2012 Sumatra MW8.6 earthquake co-seismic effect, taking into account the surface deformation and seismic effects of gravity changes from the 2004 MW9.1 earthquake. At the same time, the annual variation rates of post-earthquake deformation and gravity are given. The coseismic deformation and gravity change show the left-lateral strike-slip characteristics of the seismogenic fault; the changes mainly focus on the fault; the redistribution of seawater quality has a significant effect on the vertical displacement and coseismic gravity change. The mean annual rate of change after 50 years reveals the changes of surface deformation and gravity change. The average deformation in the near field after 50 years is 10 mm/year. The average annual deformation of the far-field is less than 1 mm/a, and the average annual variation of gravity is generally less than 0.1 μGal/a. The horizontal deformation changes obviously within 400 years after the earthquake. The rate gradually decreases and stabilizes after 800 years. The vertical displacement and gravity change are particularly notable within 100 years after the earthquake, and the rate of change rapidly decayed, and basically remained unchanged after 400 years.