四川二滩水库库区蓄水前地震序列揭示的水库诱震结构  

Reservoir induced seismicity structure revealed by the earthquake sequences at Sichuan Ertan reservoir area before filling

作　　者：赵珠[1] 龙思胜[1] 罗昭明 

机构地区：[1]四川省地震局,成都610041

出　　处：《华南地震》1999年第1期78-84,共7页South China Journal of Seismology

摘　　要：四川二滩水库地震遥测台网自运行以来，记录了库区发生的力马、田湾－金河和马鹿塘三次地震序列，主震震级分别为３．２，４．０和２．６级。利用工业爆破和天然地震资料，计算了该区域的Ｐ波和Ｓ波地壳分层速度模型。以此模型为基础，采用参考时间平均值法和数值性能极好的单纯形空间迭代寻优定位方法，修定了这三个序列的震源位置，得到精度一般小于０．３ｋｍ，最大不超过０．５ｋｍ的精确解。最后，利用定位结果，求解了田湾序列中４次Ｍ_Ｌ≥３．０地震震源机制解。从地震学的角度分析了水库蓄水后库区地下结构诱发水库地震的可能性，认为西番田、田湾－金河断裂一带是二滩库区内值得引起足够重视的潜在诱发地震危险区。The 3 earthquake sequences Lima, Tianwan - Jinhe and Malutang with the main events of M_L3.2, 4.0 and 2.6 Separately occurred at Sichuan Ertan reservoir area before filling were recorded by its seismic telemetric network. In this paper, the P wave and S wave layered velocity models in this area are Obtained by using mine explosion and earthquake observed records. Then, the hypocenter locationsof the 3 earthquake sequences are determined by adopting the velocity models given above and using the locating techniques with the - value as original reference time and simplex optimized algorithm. The hypocenter location errors may be estimated less than 0.3 km generally and the biggest errors not more than 0.5 km. On this bases, the focal mechanisms of M_L3.0 in Tianwan sequence are solved. Finally, the possibility in the underground structure inducing reservoir seismicity after Ertan reservoir filling has been discussed as viewed ho seismology. Thus, some areas nearby Xifantian fault and Tainwan - Jinhe fault would be considered as potential danger area so far as reservoir induced seismicity. It should be paid enough attention to these areas.

关 键 词：水库地震 地震序列 震源机制 地震定位 速度模型 

分 类 号：P315.9[天文地球—地震学]