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

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