由余震分布确定2017年九寨沟M_S7.0地震发震断层面参数

Fault Plane Parameters of 2017 Jiuzhaigou M_S7.0 Earthquake Determined by Aftershock Distribution

基于2017年九寨沟MS7.0地震经过重定位的4035个余震数据,利用小震确定大震断层面方法,得到该地震的断层面参数,以余震稀疏区为界将余震分为南北两段进行分段拟合,最后判定了此次地震的发震构造。结果表明:九寨沟地震的发震断层面走向151.3°、倾角84.0°,该结果可视为发震断层参数的一级近似;南、北两段的走向和倾角分别为147.4°和88.3°,162.9°和76.8°,南、北两段较大的差异可能是余震稀疏区的成因;结合周边地质构造特征,推测此次地震的发震断层为虎牙断裂NW向延伸的隐伏部分。

Based on the 4 035 relocated aftershock data of the 2017 Jiuzhaigou MS7.0 earthquake,we obtain the fault plane parameters of the earthquake by the method of determining the fault plane parameter according to the distribution of small earthquakes. Taking the sparse area of aftershocks as the boundry,the aftershocks are divided into north and south segments for segmentation fitting,and finally the seismogenic structure of the earthquake is determined. The results show that the parameters of the seismogenic fault of the Jiuzhaigou earthquake are as follows:the strike is 151.3°,the dip angle is 84.0°,the obtained parameters could be regarded as the first approximation of the fault plane parameter. The strike and dip angles of the north and south segments is 147.4° and 88.3°,169.2° and 76.8° respectively,which caused the aftershock sparse area. Combining with the surrounding structural features,we infer that the seismogenic fault of the Jiuzhaigou earthquake is a concealed fault extending northwest from the Huya fault.