大尺度断层活动性数值模拟及地震学类比

本文建立了大尺度断层（100～1000 km）的二维模型，利用ANSYS有限元软件平台，采用接触模式，模拟了百年时间尺度走滑断层的位错运动.结果表明，不同的断层力学参数，特别在断层强度非均匀分布的状态下，断层位错运动存在明显的非均匀时、空分布的特征.然而，不同模型的断层位错运动还显示出一些共同的特征，即断层位错运动表现为闭锁期、准静态预滑期和瞬间滑动，以及与之相应的应力（应变）的积累、调整和释放等等.这些结果也与实验室内小尺度的岩石物理实验相类似.与此同时，模拟结果与实际地震活动表现出的重复性和准周期特征较为相似.模拟发现，对于参数分布较为复杂的断层模型，其数值模拟提示的地震过程相对复杂得多.对于一个近尺度近1000 km，在接触面上设置了两个剪切强度相对较大区域的断层模型而言，模拟对应地震活动显示，其模拟地震断层位错分段发生，其高强度的区域基本控制了断层的地震位错运动.整个断层的模拟地震位错呈现出了地震触发、震中迁移、大震重复等与实际地震活动性相似的特征.

Numerical simulation of large scale fault activity and it's seismological analogy

Using contact algorithm in finite element method (FEM), we have established 2D large scale faults models and simulated the dislocation of strike-slip faults in hundreds of years. The results show that the dislocations were nonlinear in space and time, especially in non-homogenous distribution of mechanical parameters on the fault surface. But different models show the same characters such as stick period, pre-slip period and instantly slip period. These results were resembled with experiments in laboratory. Additionally the simulation results were resembled with natural earthquakes in repetition and quasi-periodicity. In the model of 1000 km long fault, which we set two strong fault regions with high friction coefficient, the simulation results indicates, the simulated earthquakes were occurred in separate parts, and the strong fault regions control all fault's activity. We can also find the trigger of earthquake, transfers of the simulated earthquakes and the repetitions of large earthquakes in this model. The characteristics of large scale fault activity are comparable with the natural faults.