2018年印尼帕卢M_W7.5地震——一次超剪切破裂事件

The 2018 M_W7.5 Palu,Indonesia earthquake:A supershear rupturing event

利用反投影方法,使用日本密集台网Hi-net远场垂直分量568条P波资料对2018年9月28日印尼帕卢MW7.5地震震源破裂过程进行成像,结果显示此次地震的能量释放比较集中,主要集中在10~20s之间.破裂有两个集中区,破裂峰值分别位于12s和19s,最大能量释放区域位于震中南侧约0~50km内,另一破裂集中区覆盖了帕卢市及周边区域.破裂主要向南侧延展,破裂总长度至少100km,平均破裂速度约4.1km·s^-1,属于一次超剪切破裂事件.

In this study,we used the vertical components of 568 teleseismic P-wave records from the Hi-net array and back-project method to image the rupturing process of the M W7.5 Palu,Indonesia,earthquake on September 28,2018.The results show that the rupture initiated from the epicenter located by USGS,then propagated to the south along a nearly NS-trending fault and finally ended at least 100 km to the start point.The most of the earthquake energy was released during the first 10~20 s after the initiation of the event.There are two main rupture zones,corresponding to two peak ruptures at 12 s and 19 s after the mainshock,respectively.The maximum energy release area is located approximately 0~50 km south of the epicenter,and the other one covers the city of Palu and its surrounding areas.The estimated average rupture velocity is about 4.1 km·s^-1 which is larger than the S wave velocity,indicating that the earthquake is a supershear rupturing event.