几何弯曲断层活动性的模拟  

The simulation of activities of bend fault

作　　者：薛霆虓[1,2] 傅容珊[1,2] 林峰[1,2] 

机构地区：[1]中国科学技术大学地球和空间科学学院,合肥230026 [2]蒙城地球物理国家野外科学观测研究站,合肥230026

出　　处：《地球物理学报》2009年第10期2509-2518,共10页Chinese Journal of Geophysics

基　　金：国家自然科学基金(40574043)资助

摘　　要：运用有限元法建立大尺度几何弯曲断层(长约750 km)的二维模型,并利用接触单元技术模拟断层间的作用,模拟了几千年时间尺度内走滑断层的活动,探讨了具有一定几何形态断层对断层系统活动的影响.几何弯曲的断层导致了应力的集中,而且在断层的地震事件中起到了抑制作用,但是也为孕育大震提供了条件.和平直断层的模拟结果比较得知,断层的儿何弯曲不仅影响地震破裂长度、改变了地震滑移量,也很大程度影响了能量释放的空间位置,改变了地震轮回周期.此外,弯曲断层应力的不均匀也使主震前往往有前震发生.另外通过模拟可以看出.弯曲断层活动表现出明显的特征地震,使得地震一频次曲线偏离GR公式,说明了对单个断层而言,特征地震可能更能体现断层的地震活动,这对我们进行地震预测和危险性分析有着很重要的参考意义.Using finite element method （FEM） with contact algorithm, we established a 2D bend fault model and calculated the activities of this fault in thousands of years, and discussed how the geometry bending affects the activities. Due to the effect of geometry bending, stress concentrates on some parts of fault and the distribution of stress on fault is highly heterogeneous. Additionally, geometry bending restrains or stops some ruptures, but can produce strong earthquakes. Compared with planar fault, bend fault can not only affect earthquake ruptures and slip, but also change temporal and spacial evolution of earthquakes. Because of the heterogeneous stress distribution of bend fault, some foreshocks occurred before main shock, but not occurred on planar fault. The earthquake frequency-size distribution of simulation result deviates from the G-R relation, showing that a characteristic model is more reasonable, especially, characteristic slip can be seen from result distinctly.

关 键 词：几何弯曲断层 有限元 断层活动性 数值模拟 

分 类 号：P315[天文地球—地震学]