2009年7月9日姚安MS6.0地震破裂方向性研究

Rupture Directivity of the July 9,2009 Yao'an MS6.0 Earthquake

摘要:

2009年7月9日19时19分，云南姚安发生M_S6.0地震。10日17：02、13日00：01又相继发生M_S5.2、M_S4.7地震。利用近震CAP方法反演震源机制解发现，此次地震震源破裂方式以走滑为主，主震震源机制解2个节面走向分别为203°、295°。已有的考察资料尚未显示活动，故难以确定实际发震面。为此，采用相对质心震中确定破裂方向性的方法，利用主震与参考地震之间的P波到时差和CAP反演输出的波形时移，计算得到姚安地震起始震中与质心震中间的差异，推断震源机制解中走向为295°的节面为实际发震面，并对定位误差、发震时刻不准确以及机制解差异等因素进行了分析，发现这些因素对确定发震断层影响不大。

Abstract:

The Yao'an,Yunnan M_S6.0 earthquake occurred at 19:19 of July 9,2009. At 17:02 of July 10 and 00:01 of July 13,the M_S5.2 and M_S4.7 earthquakes occurred. We applied the Cut-And-Paste(CAP)method to determine the focal mechanism,and found the earthquake is a strike-slip event,with two nodal planes striking 203 degrees and 295 degrees. Active faults have not been found in previous regional geological survey,so it is difficult to determine the seismogenic fault. We use the relative centroid location method to determine the earthquake's rupture directivity,and found that the nodal plane with the strike of 295° is the ruptured plane. We also investigated the result's robustness against the error of location,original time and focal mechanism,and found the resolved rupture directivity is stable.