九寨沟MS7.0地震震源机制解及构造应力场研究

Focal Mechanism Solution and Tectonic Stress Field of the Jiuzhaigou MS7.0 Earthquake

摘要:

2017年8月8日四川九寨沟县发生M_S7.0地震。根据中国地震台网固定台站的记录波形，利用gCAP方法和P波初动符号反演方法求解了主震的震源机制解，其结果与哈佛CMT震源机制解、美国地质勘探局发布的震源机制以及中国地震局发布的各震源机制解有很好的一致性。此外，还求解了九寨沟地震震中附近2010—2016年间28次小震的震源机制解，利用得到的小震震源机制解反演了该区域的构造应力场。结果表明，这一区域构造应力场的最大应力轴与最小应力轴均为水平方向，其中最大应力轴方向为NWW方向，最小应力轴方向为SSW方向。

Abstract:

The Jiuzhaigou M_S7.0 earthquake occurred in Jiuzhaigou County, Sichuan Province on August 08, 2017. In this paper, the focal mechanism of the main shock was determined using gCAP and P-wave first motion methods based on the waveforms recorded at fixed stations in the China Earthquake Network Center. This proved to be consistent with the solutions published by Harvard CMT, the United States Geological Survey, and the China Earthquake Administration. We also determined the focal mechanisms of 28 small earthquakes that occurred in the region of the Jiuzhaigou M_S7.0 earthquake from 2010 to 2016, and by the focal mechanisms the tectonic stress field in the area was inverted. The results show that the direction of the maximum and minimum principal stress axes was NWW and SSW, respectively, both in the horizontal direction. After the Jiuzhaigou M_S7.0 earthquake, a series of aftershocks occurred, and, as they should continue for a certain time, we expect to eventually have more data for analysis of the changes in the tectonic stress field.