对长江三峡水库诱发地震的探讨

Discussion on Earthquakes Induced by Three Gorges Reservoir

长江三峡水库已初步形成,随着蓄水位上升,库容及水域面积加大,发生水库诱发地震的可能性也将加大。根据最大历史地震震级并适当加权,确定库区最大可信地震为6级左右,对坝址所受影响烈度为Ⅵ度,不会对按烈度Ⅶ度设防的枢纽主要建筑物构成直接威胁。三峡水库蓄水运行后,地震频次与强度虽有所增加,但地震活动仍保持在三峡地区原有弱地震活动本底状态。必须加强对三峡水库诱发地震的监测与探讨,预防地震及地质灾害,确保工程建设及运行安全,库区长治久安,构建和谐社会。

It is well known that earthquakes can be induced by reservoirs .And the probability of reservoir induced earthquake will increase with the increase of water level .According to historical magnitude records of maximum earth-quakes and a proper weighting calculation , the maximum reliable earthquake in the Three Gorges reservoir area is deter-mined to be Ms 6 magnitude .The corresponding earthquake intensity around the dam site would not exceed VI degree , whereas the main structures of the project are designed with an anti -seismic intensity of VII degree .Thus, the reservoir induced earthquakes would not cause direct damage to the main structures .It is also observed that the frequency and in-tensity of earthquakes has been increased in some extent after the impoundment and operation of the reservoir .Yet the earthquake activities in the reservoir area are still in an original weak status .Nevertheless, monitoring and research on the reservoir induced earthquakes in the Three Gorges reservoir area are of great necessity to prevent geological disasters and to ensure the operation safety of the project .