广东及邻区地震的震源机制特征

Characteristics of Focal Mechanism in the Guangdong and Its Adjacent Areas

用初动和振幅比的方法求解广东台网运行以来32个3级以上地震的震源机制解,整理前人求得的83个广东及邻区地震的震源机制结果,分析总结了广东省及邻区的震源机制特征,同时对阳江、新丰江和南澳3个老震区各自的震源机制分别进行了探讨。结果表明,应力作用方式和性质有明显的区域特征,地震多数以走滑错动为主,兼具倾滑分量;新丰江水库地震由于水库诱发的特殊性,只有走滑型和正断型的情况;阳江地区出现一些逆断型地震;主压应力P轴优势方向从广西海南的NS向到广东的NWW向,最后表现为粤闽沿海的近EW。

Using a method of mechanism determinations wave with their amplitude ratio, the focal mechanisms of 3 combining the polarities of P, SV and SH 2 earthquakes with ML≥3.0 are calculated since the Guangdong Digital Seismological Network had been built, and coordinated the focal mechanisms of 83 earthquakes in the Guangdong and its adjacent areas. The characteristics of the focal mechanism are studied, especially in three earthquake areas of Yangjiang, Xingfenjiang and Nan＇ao. Results show clear regional characteristics with action and characteristics of stress. The most earthquakes are strike slip with relatively small dip motion component. Earthquakes in the Xinfengjiang reservoir area are strike slip and normal rupture because of the reservoir induced; The earthquakes include some reverse rupture in the Yangjiang area; the maximum principal stress axis of synthetic direction is changed from NS of Guangxi, Hainan to NWW of Guangdong to near EW of Yuemin coast.