江西瑞昌4.6级地震震源机制与发震构造研究

FOCAL MECHANISM SOLUTIONS AND SEISMOGENIC STRUCTURE OF Ms 4.6 JIANGXI-RUICHANG EARTHQUAKE

基于湖北、江西区域台网共9个台的宽频带数字地震记录,采用CAP法反演江西瑞昌2011年9月10日Ms 4.6地震震源机制解,其最佳双力偶解为节面I走向204°,倾角79°,滑动角-22°;节面Ⅱ走向298°,倾角68°,滑动角-168°;最佳震源深度主要分布在14 km附近;结果分析认为:此次地震主压应力P轴近NS向,主张应力轴近EW向,类型为正断;其最大余震为当日23时36分原震中位置Ms 2.8级地震,类型为倾滑正断;余震序列主要呈NNE分布,个别呈NW方向分布。由此推断该地震发震构造与2005瑞昌5.7级地震的发震构造为同一组构造系列,从地表考察判断其与NE向枫林桥断裂有关。

Based on the waveform records of 9 seismic stations belong to Hubei and Jiangxi regional seismic network, we obtained the focal mechanisms of the Ms 4.6 with the CAP method. The result shows that the best double Jiangxi-Ruichang earthquake on September 10 in 2011 couple solutions are 204°, 79°and - 22° for strike, dip and slip angles, respectively, the other nodal plane is 298°, 68°and -168°. The optimum focus depth is 14 km. The result shows that the principal stress P axis of the earthquake is mainly in NS, the lord tension T shaft is mainly in EW; the biggest aftershoek is Ms2.8 which is also normal dipslip fault. And aftershoeks sequences mainly propagated along NEE, very few aftershocks propagated along NW. So we infer that the Ms 4.6 earthquake and aftershocks are caused by the NE strike in Fenlinqiao fault from the earth＇ s surface investigation, and the seismogenie structure is the same to the Ms 5.7 Ruichang earthquake in 2005.