Abstract: Based on field investigation in the reservoir head area of the Yangtze Three Gorges,combining with its seismogeological background and past research achievements,the reservoir head area is divided into 31 predictive units,and together with 8 impact factors,the possibility and magnitude of reservoir induced seismicity(RIS)are predicted using statistical forecasting model.The results show as follows:(1)it is quite possible that M_L=3.0～4.5 earthquakes will be triggered along the Jiuwanxi-Lukouzi Fault and Xiannvshan Fault in the reservoir area;(2)According to the analysis of earthquakes at home and abroad,the RIS takes place mainly in carbonatite and igneous rocks,and concentrates in karst developing segment,yet it is little possible that earthquake happens in clastic rock area.From the predictive results,it is possible to trigger M_L 4.5～6.0 earthquake in two places,the limestone area of southern Badong and the limestone area on the Gaoqiao Fault;(3)Around the Gaoqiao Fault,tectonic reservoir-induced earthquake is quite likely to occur.Geological investigation shows that the M_L 5.1 Longhuiguan earthquake in 1979 was possibly related to the Gaoqiao Fault which had a certain activity during the early period of reservoir impounding.The maximum magnitude of earthquake happening around the Gaoqiao Fault reaches to M3.3.The bigger earthquakes might be induced near the reservoir segment of Gaoqiao Fault along with the water storing to the design level.

Key words: RIS, statistical forecasting model, impact factors, magnitude, reservoir head area of the Three Gorges Reservoir

摘要： 通过实地考察并结合前人的研究成果,在地震地质背景研究的基础上,将长江三峡工程坝址至巫山库段划分为5个预测区共12个预测单元,选用8个诱震因素,运用统计预测模型预测了水库诱发地震的可能性及诱发地震震级。结果表明,库水蓄至最高水位,三峡工程坝址至巫山库段中多数预测单元诱发微震和不发生地震的概率值高,无震可能性较大。但九湾溪断层沿线、仙女山断层库段具备诱发3.0～4.5级或4.5～6.0级地震的可能;考虑到龙会观5.1级地震与高桥断裂的关系,预测结果显示高桥断裂沿线具有诱发强烈水库地震(≥6.0级)的可能性,其预测概率值为0.23。

关键词: 水库诱发地震, 统计预测模型, 诱震因素, 震级, 三峡库首区