米林地震的断层破裂过程及近断层地震动特性研究

The fault rupture process and its near-fault ground motion of the Milin earthquake

为了从应力角度揭示2017年西藏米林Ms6.9地震的断层破裂过程,获取该次地震的地震动近断层特性,基于动力学震源模型,以有限断层运动学震源模型反演结果为约束,通过试错法给定震源动力学计算参数,采用谱元法(SPECFEM3D程序)进行了2017年米林Ms6.9地震的单、双断层模式震源破裂过程模拟,对比分析了断层模式对震源破裂过程的影响,分析了模拟地震动的近断层效应。结果表明:构建的动力学震源模型可以很好地再现米林地震的破裂特征;地表地震动具有显著的上盘效应和集中性效应;诱发断层会抑制孕震断层的破裂发展,会局部促进地表地震动的发展,但在整个地震事件中作用有限。

In order to reveal the fault rupture process of the Ms6.9 earthquake in Milin,Xizang Autonomous Region of China in 2017 from the perspective of stress,the ground motion near-fault characteristics of the earthquake were obtained,based on dynamic source model and constrained by the inversion results of finite fault model,the calculation parameters of source dynamics were given by trial and error method,and the source rupture process of the 2017 Milin Ms6.9 earthquake under single fault rupture and double fault rupture was simulated by using the spectral element method.The influence of fault model on the focal rupture process and the near-fault effect of simulated ground motion were analyzed.The results show that:the dynamic source model can well reproduce the fracture characteristics of the Milin earthquake;ground motion has significant updisk effect and centrality effect;the induced fault can inhibit the rupture development of seismogenic faults and locally promote the development of ground motion,but have limited effect in the entire earthquake event.