2014年于田M_S7.3地震对后续余震和远场小震活动的动态应力触发  

Dynamically triggered aftershock activity and far-field microearthquakes following the 2014 M_S7.3 Yutian,Xinjiang Earthquake

作　　者：王琼[1] 解朝娣[2] 冀战波 刘建明[1] 

机构地区：[1]新疆维吾尔自治区地震局,乌鲁木齐830011 [2]云南大学资源环境与地球科学学院,昆明650091 [3]中国地震局地球物理研究所,北京100081

出　　处：《地球物理学报》2016年第4期1383-1393,共11页Chinese Journal of Geophysics

基　　金：地震科技星火计划项目(XH13027)资助

摘　　要：本文采用离散波数法,计算了2014年于田MS7.3地震的断层破裂在近场和远场产生的库仑破裂应力变化,并结合地震活动特征,讨论了MS7.3地震对后续余震活动和远场区域小震活动的动态应力触发作用.结果表明,1 MS7.3地震产生的库仑破裂应力变化对其西南侧主体余震区的地震活动起到了抑制作用,这可能是本次MS7.3地震序列余震活动水平不高的主要原因;距主震约30km的北东方向余震区后续地震活动受到了主震产生的动态和静态应力变化的共同触发作用,动态应力变化峰值为2.78 MPa,静态应力变化为0.80 MPa,这与该区余震较为活跃相一致;距主震约45km的北部余震区受到动态应力触发作用,应力变化峰值为0.72 MPa.2 MS7.3地震产生的动态库仑应力变化空间分布呈非对称性,其中北东方向、北部余震分布与动态应力变化正值区存在相关性,从应力变化的角度解释了MS7.3地震的后续余震空间活动特征.3 MS7.3地震在沙雅、伽师地区的远场接收点产生的动态应力变化峰值分别为0.09 MPa、0.1 MPa,对两个区域的小震活动具有动态触发作用.We systematically examine how dynamic stresses from seismic waves following the2014 MS7.3Yutian,Xinjiang,earthquake affect aftershocks and regional microseismicity in the near and far field.The full Coulomb stress changes are computed based on the discrete wavenumber method.We find that the static Coulomb stress changes caused by the MS7.3earthquake discourage aftershocks occurrence in the southwestern part of the aftershock zone,which may explain why the aftershock activity in this region is relatively weak.Aftershock rates at the region about 30 km to the northeast of the mainshock are relatively high,which are consistent with positive dynamic and static stress changes in that region,with the peak values of 2.78 MPa and0.80 MPa,respectively.Aftershocks about 45 km north of the mainshock are mostly triggered by the dynamic stress change with a peak value of 0.72 MPa.The peak values of dynamic stress change in the remote Shaya and Jiashi areas are 0.09 MPa and 0.1MPa,respectively,which are high enough to trigger microearthquakes in these areas.Overall the spatial distributions of dynamic stress changes induced by the Yutian mainshock show asymmetrical patterns,and there is a positive correlation between the aftershock distribution and the positive area of dynamic stress change in the northeastern and northern regions.

关 键 词：2014年于田MS7.3地震 库仑破裂应力变化 动态应力触发 区域地震活动 

分 类 号：P315[天文地球—地震学]