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 M_L ≥ 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 M_L5.5, Zigui M_L4.7 and Zigui M_L5.1 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.

Key words: apparent stress, spatial-temporal feature, Three Gorges, Badong earthquake

摘要： 三峡库区地震成因复杂，为了研究该区域地震的成因及发震规律，文中利用湖北省区域台网、三峡台网提供的数字波形资料，计算2010年1月1日至2015年12月31日三峡库区394个M_L ≥ 2.0地震的震源参数，获得了三峡库区视应力的时空分布图像，分析了三峡库区研究时间段显著地震事件前后的视应力时空演化特征。研究表明：1）巴东M_L5.5、秭归M_L4.7以及M_L5.1地震发生前后，不同震级分段计算结果显示，震前震中区附近新华-水田坝断裂和高桥断裂同时出现高值，高值区域分布呈现协同化程度高，而震后零散的现象，表明该区域在震前积累了较高的应力。2）研究区域视应力在地震前后经历了一个明显的"上升-下降"过程，在应力上升初期发生了巴东M_L5.5、秭归M_L4.7以及M_L5.1三次显著地震。3）研究区域视应力深度剖面显示，不同深度视应力与震级大小呈现正相关性，震后研究区内小震属于低应变释放背景下的低应力释放，未新增明显视应力异常集中区域，震后巴东高桥断裂、周家山-牛口断裂以及秭归仙女山断裂短期内发生破坏性地震的可能性不大。

关键词: 视应力, 时空特征, 三峡库区, 巴东地震