SEISMOTECTONICS OF THE 8 AUGUST 2017 JIUZHAIGOU EARTHQUAKE AND THE THREE-DIMENSIONAL FAULT MODELS IN THE SEISMIC REGION |
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| Authors: | LU Ren-qi XU Xi-wei CHEN Li-chun CHEN Gui-hua YAO Qi SUN Jian-bao REN Jun-jie REN Zhi-kun XU Chong WEI Zhan-yu TAN Xi-bin DONG Shao-peng SHI Feng WU Xi-yan |
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| Institution: | 1. Key Laboratory of active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;
2. China Earthquake Networks Center, Beijing 100045, China;
3. Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China |
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| Abstract: | On 8 August 8 2017, an MS7.0 earthquake occurred in Jiuzhaigou County, Sichuan Province. Field geological investigations did not find any co-seismic surface rupture in the epicenter area, implying that the seismogenic structure is likely a hidden active fault. Based on the results of the relocated aftershocks, the seismogenic fault was simulated and characterized using the SKUA-GOCAD software. The three-dimensional model of the seismogenic fault was preliminarily constructed, which shows that the main shock of the Jiuzhaigou MS7.0 earthquake occurred at the sharp bending area of the fault surface, similar to the geometry of the active fault that generated several major earthquakes in the Songpan area during 1973-1976. Our study suggests that high seismicity of this area may be closely related to the inhomogeneous geometry of the fault surface. In this work, we collected the historical earthquakes of M ≥ 6.5, and analyzed the geometric and kinematic features of the active faults in the study area. A three-dimensional fault model for the 10 main active faults was constructed, and its limitation in fault modeling was discussed. It could provide evidence for analyzing the seismotectonics of historical earthquakes, exploring the relationships between earthquakes and active faults, and predicting major earthquakes in the future. |
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| Keywords: | Jiuzhaigou earthquake Seismogenic fault simulation Inhomogeneous fault surface Northern Huya Fault Three-dimensional model |
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