Relocation of the aftershock sequence of the MS7.0 Jiuzhaigou earthquake and its seismogenic structure

On August 8, 2017, an M_S7.0 (M_W6.5) earthquake occurred in Jiuzhaigou County, Sichuan Province. The epicenter is located in the intersection between eastern part of eastern segment of Kunlun faults and Minjiang faults in the eastern part of Bayan Har block of the Qinghai-Tibet Plateau. The main active faults around epicenter include Tazang, Minjiang and Huya faults in the eastern Kunlun faults. The epicenter of the Jiuzhaigou earthquake and its adjacent area have been identified as a seismic gap with a severe earthquake risk. This area has also caused wide public concern because it shows many characteristics, such as the low b-value, the strong locked condition under relatively high stress and the fact that it is affected by the Coulomb stress induced by the 2008 Wenchuan earthquake.

This study, based on the previous work, is aimed at determination of the three-dimensional P-wave velocity structure near the epicenter and relocating the Jiuzhaigou earthquake and its aftershocks by using the double difference seismic tomography method and making full use of the absolute first arrival P-wave arrival times and high quality relative P-wave arrival times recorded by the regional networks and mobile stations. Then, we will analyze and discuss the fine seismogenic structure of Jiuzhaigou earthquake using the relocation results and three-dimensional P-wave velocity structure. The results will be important for understanding the seismogenic environment of the Jiuzhaigou earthquake, and will provide basis for the estimation of the potential strong seismic in the study area.

This work is financially supported by the Natural Foundation of China (Grant No. 41504047).