2015年7月3日新疆皮山MS 6.5地震序列震源机制解及发震构造分析

2015年7月3日09时07分,在新疆皮山县发生M_(S)6.5地震,震源深度约10 km,主震后一段时间内陆续发生一系列大小不等的余震。使用新疆测震台网原始波形数据和中国地震台网编目数据库震相数据,采用CAP方法反演皮山M_(S)6.5地震及M_(S)3.5以上余震序列震源机制解,得到震源机制解参数,其中:节面Ⅰ走向为136°,倾角为34°,滑动角为94°;节面Ⅱ走向为311°,倾角为56°,滑动角为87°;最佳震源深度为21.3 km;矩震级为M_(W)6.3。据皮山地区地质构造和余震序列展布,基本确定节面Ⅰ为发震断层面;通过震源球判定本次地震的断层活动主要表现为逆冲型特征,破裂优势方向SE,倾角以20°—40°居多,滑动角以70°—120°居多。

Analysis of seismological structure and focal mechanisms of the Pishan MS 6.5 earthquake on July 3, 2015

On July3, 2015, an earthquake with magnitude 6.5 occured in Pishan, Xinjiang, the focal depth is about 10 km, then a series of aftershocks sequence have been happened after the main shock. Based on the digital waveform of Xinjiang Seismic Network and data case, phase from CENC, we obtained focal mechanisms of the main shock and some aftershocks which M_S ≥ 3.5 by CAP method. The focal mechanism of this earthquake by CAP method of Nodal planeⅠ:strike 136°, dip 34° and slip 94°; Nodal planeⅡ:strike 311°, dip 56?nd slip 87°, the optimal is about 21.3 km, moment magnitude is 6.3. According to geological structure and distribution of the aftershock sequence, we can determine nodal planeⅠ is the fault plane; By the the focal mechanism we can determine activity of the fault maybe a thrust type, the broken advantage direction is SE, dip in the majority with 20°-40°, sliding angle in the majority with 70°-120°.