2011年M_S 4.6瑞昌-阳新地震的震源机制及发震构造探讨

FOCAL MECHANISMS AND SEISMOGENIC STRUCTURES OF THE M_S 4. 6 RUICHANG-YANGXIN EARTHQUAKE OF 2011

2011年MS4.6瑞昌-阳新地震是瑞昌地区继2005年M5.7地震后的又一中等强度地震,文中从多角度对此次地震的发震构造进行了探讨。利用双差定位法进行的地震精定位结果显示,主震发生在NE向断裂的西南端,余震的分布则呈现出沿NNE和NW两个方向展布的特征。野外考察发现,等震线长轴方向为NE,沿此方向烈度衰减较慢。考虑震源时间函数的影响,采用波形反演方法得到了此次地震的震源机制解。节面Ⅰ走向302.2°,倾角68.2°,滑动角-3.8°;节面Ⅱ走向33.6°,倾角86.5°,滑动角-158.1°。综合分析认为,NNE向郯庐断裂的南端隐伏段(瑞昌-武穴断裂)为此次地震的发震构造,而与NW向断裂的共轭作用造成了部分余震沿着NW向分布的特征。

Ruichang-Yangxin earthquake is another moderate-size earthquake in the Yangxin-Jiujiang area since the MS. 7 Jiujiang-Ruichang earthquake in 2005. In order to have a better understanding of the seismic activities in this area,we investigate the moment tensor solution and the seismogenic structure of Ruichang-Yangxin earthquake. Precise earthquake relocation shows that the main shock occurred on the southwestern part of the NE-trending fault and aftershocks are distributed along both NNE and NW directions. By comprehensive analysis of the earthquake distribution, isoseismal features, focal mechanism, and regional structure characteristics, it is inferred that the this earthquake is caused by the southern segment of the NNE-trending Tanlu Fault （TLF）. In addition, it has close relationship with the conjugated NW-trending fault as well.