APPARENT STRESS VARIATION CHARACTERISTICS BEFORE AND AFTER BADONG EARTHQUAKE IN THE THREE GORGES RESERVOIR AREA |
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| Authors: | DAI Miao WU Gui-ju LIU Jian SHEN Chong-yang SHEN Xue-lin SHEN Xue-lin WEI Gui-chun |
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| Affiliation: | 1.Key Laboratory of Earthquake Geodesy, Institute of Seismology, China Earthquake Administration, Wuhan 430071, China;2.Hubei Key Laboratory of Earthquake Early Warning, Institute of Seismology, China Earthquake Administration, Wuhan 430071, China;3.Earthquake Administration of Hubei Province, Wuhan 430071, China |
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| Abstract: | The causes of earthquakes in the Three Gorges reservoir area are complex. In order to study the cause of earthquakes happening in the region, we calculated the source parameters of 394 ML ≥ 2.0 earthquakes occurring in Three Gorges reservoir area based on waveform data observed by the regional seismic network of Hubei Province and Three Gorges, obtained the apparent stress spatial-temporal variation map of Three Gorges reservoir area, and analyzed apparent stress spatial-temporal variation characteristics before and after the main earthquakes in the Three Gorges reservoir area. The results show that:1)Before the Badong ML5.5, Zigui ML4.7 and Zigui ML5.1 earthquake, high apparent stress of earthquakes with different magnitudes is concentrated in Xinhua-Shuitianba Fault and Gaoqiao Fault. The distribution of high value area shows the high degree of synergism before the earthquake and the scattering after the earthquake, which indicates that the area accumulated a high stress before the earthquake, and the fault was in a locked state; 2)In the study area, the apparent stress before and after the earthquake showed significant rise in the first and then decline, the earthquake occurred in the process of rising; 3)Apparent stress depth profiles show that apparent stress at different depths has a positive correlation with the size of magnitude of earthquake, and the phenomenon of "small magnitude and strong apparent stress" did not appear. The small earthquakes occurring after the major earthquakes in the study area belong to low strain release under the background of low stress release, and there are no new apparent stress anomaly concentration areas appearing, this indicates that the Badong-Gaoqiao Fault, Zhoujiashan-Niukou Fault and Zigui Xiannushan Fault have been effective in releasing after the Badong earthquake and Zigui earthquakes and the probability of destructive earthquake is small on these faults. |
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| Keywords: | apparent stress spatial-temporal feature Three Gorges Badong earthquake |
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