2009年云南姚安6.0级地震震源机制与发震构造的分析研究

利用P波、SV波、SH波初动及其振幅比联合反演震源机制解的方法,计算了2009年7月9日发生在云南姚安6.0级地震余震序列的震源机制解,同时结合地震序列的空间分布,对姚安6.0级地震的发震断层性质和震区应力场特征进行综合分析。结果分析表明：（1）姚安6.0级地震发震断层为NWW—SEE向的直立右旋走滑断层,与美国哈佛大学的主震CMT解节面基本一致,也与余震优势方向分布一致,证明结果可靠;（2）震区主压应力场优势方向为NNW—SSE向,与其现今区域构造应力场主压应力NNW—SSE向一致,表明主震应力场主要受到现今区域构造应力场的控制,同时还有一些小的余震与主震应力场不同,表明震区应力场的多样性和复杂性;（3）结合本次地震序列的空间分布、震源机制解特征、震区断裂构造特征综合分析,综合判定姚安6.0级地震的发震构造属于马尾箐断裂。

ANALYSIS ON FOCAL MECHANISM AND SEISMOGENIC STRUCTURES OF YAOAN EARTHQUAKE WITH Ms6.0, 2009

Using joint inversion method with amplitude ratio of P wave、SV wave and SH wave,this paper calculated focal mechanism of aftershock sequence of Yaoan earthquake with MS6.0.According to the space distribution of earthquake sequence,the author analyzed the characteristics of stress field and seismogenic fault.The result showed that:(1) seismogenic fault of Yaoan earthquake was a vertical right-lateral strike-slip fault,striking NWW—SEE.The result was reliable,also consistent with nodal plane of CMT result offered by Harvard and predominant direction of aftershocks;(2) predominant direction of principal compressive stress in NWW—SEE was consistent with regional tectonic stress,and some aftershocks were different from main shock.Stress field of main shock was controlled by regional tectonic stress,indicated diversity and complexity in seismic area;(3) analyzing the distribution of earthquake sequence、focal mechanism and fault structure in seismic area comprehensively,seismogenic structure of Yaoan earthquake belongs to Mawei-jing fault.