2012年6月30日新疆新源-和静MS6.6 地震发震构造初步研究

2012年6月30日新疆维吾尔自治区新源-和静县交界发生M_S6.6地震，该地震是2010年青海玉树7.1级地震和2013年4月20日四川芦山7.0级地震之间中国大陆发生的最大的地震.本文基于新疆数字地震台网记录的此次地震序列震相资料，分别用绝对和相对定位方法联合对其进行重新定位，重新定位后余震展布为NW向，主震位置为43.429°N，84.755°E，深度为21.8 km.基于新疆地震台网记录6.6级地震波形数据，本文用CAP方法反演了震源机制解和震源深度.结果显示：M_S6.6地震震源机制解：节面Ⅰ走向39°，倾角46°，滑动角12°，节面Ⅱ走向301°，倾角81°，滑动角135°；震源深度为21 km，与利用地震震相到时确定的主震震源深度基本一致.主震震源机制解的节面Ⅱ与伊犁盆地北缘断裂走向和倾角基本一致，综合精确定位余震展布和伊犁盆地北缘断裂性质分析认为，新源-和静M_S6.6地震发震构造是伊犁盆地北缘断裂，震源深度为21 km左右，是一个高角的内陆倾滑地震.

A preliminary study of seismogenic structure for the Xinyuan-Hejing,Xinjiang MS6.6 earthquake of June 30, 2012

On June 30, 2012, an M_S6.6 earthquake occurred at the border between Xinyuan and Hejing counties, Xinjiang Uygur Autonomous Region. It is the largest earthquake between the M7.1 Yushu, Qinghai Province event in 2010 and the M7.0 Lushan, Sichuan Province event in 2013. Based on seismic phase data of the earthquake sequence recorded by the Xinjiang Digital Seismic Network, we relocated the M_S6.6 and its aftershocks by the absolute and relative location methods. The epicenter location of the mainshock is 43.429°N,84.755°E, the focal depth is 21.8 km,and the aftershocks are distributed in NW direction. In terms of the waveforms of the M6.6 earthquake, we used the CAP method to make a grid search for the focal mechanism and the focal depth. The resulting focal mechanism solution includes 39°, 46°, 12° for the strike, dip, and rake angles on one plane and 301°,81°,135° on the other plane, respectively, and a focal depth of 21 km. So, the waveform inversion result is consistent with that by phase data. The strike and dip angles for the plane Ⅱ of the focal mechanism solution are close to the Northern Edge fault of the Yili basin, and the relocated distribution of the aftershocks is also in agreement with the characteristics of the fault. Therefore, this fault should be the seismogenic structure of the Xinyuan-Hejing M_S6.6 earthquake, which is of high angle and dip-slip in nature.