2013年1月29日哈萨克斯坦M_S6.1地震序列的震源机制解分析

ANALYSIS OF FOCAL MECHANISM SOLUTION OF KAZAKHSTAN M_S6. 1 EARTHQUAKE SEQUENCE ON JANUARY 29,2013

北京时间2013年1月29日,哈萨克斯坦发生M S6.1地震,为了提高对地震震源机制解的认识,并进一步了解震源区的应力场特征,利用CAP方法反演了此次地震序列震源机制解。反演结果表明,M S6.1地震节面Ⅰ的参数:走向241°,倾角80°,滑动角7°;节面Ⅱ的参数:走向150°,倾角84°,滑动角170°;P轴方位为196°,倾角2°,T轴方位为105°,倾角12°;矩震级M W为6.1;矩心深度为13km;震源类型是左旋走滑型。此次地震序列破裂优势方向为NEE—SWW,倾角以30°~60°居多,滑动角以60°~120°、-60°^-120°居多;P轴方位的优势取向为近NE—SW向,接近水平的居优;T轴优势取向为近SEE—NWW向,接近垂直的居优;震源机制类型以倾向滑动型为主。反演结果与断层的分布、余震分布及哈萨克斯坦中天山(伊犁盆地西部)NEE—SWW向应力场有很好的一致性。

Kazakhstan Ms6.1 earthquake occurved on January 29th, 2013. The epicenter is 38 km away from China borderline. People in the Yili river valley generally felt the shaking. In this article, we use the CAP method to invert the focal mechanism of Kazakhstan Ms6.1 earthquake and 15 after- shocks to study the stress field in the focal region. The main research contents of this paper are as follows ： （ 1 ） The result of the main shock is ： the strike, dip and rake angles ot nouai plane Ⅰ are 241 ° , 80° and 7°; And those of nodal plane Ⅱ are 150°, 84°and 170° ;The azimuth and dip angle are 1960and 20for p axis;105°and 12°for T axis;The moment magnitude is 6.1 ;The focal depth is about 13 km. Characteristics of earthquake dislocation is left-lateral strike-slip. The result in this paper is consistent with that of Harvard University. （2） The predominant rupture direction of this seismic sequence is NEE--SWW and near 240°. The dip angles are between 30°and 60°. The sliding angle is mainly distributed between the 60 ° 120 °, - 60° - - 120°. Focal mechanism type is mainly oblique slip. The predominant orientation of P axis is near NE--SW （225°） and horizontal direction, and that of T axis is near NWW-SEE （115°） and vertical direction. The focal area is affected by NE horizontal compressive stress. Since the NEE-SWW strike agrees with the distribution of the aftershocks and the earthquake scientific investigation, nodal plane I is regarded as the main rupture plane of the main shock. （3） The dislocation characteristics of the main shock and tectonic movement characteristics of Nalati deep fault belt are consistent. Focal mechanism solutions of partial aftershocks are inconsistent with the main shock, some are normal and reverse faults, the possible reason is the stress changed near source region after the main shock.