四川长宁地区地震震源参数的时空分布特征

使用谱比法计算得到四川长宁地区2018年12月至2019年7月期间442个地震的震源参数,并进一步分析了震源参数之间的相互关系及应力降的时空分布特征.研究区的地震活动主要集中在长宁背斜核部和南部建武向斜页岩气开采区.研究结果显示,该地区ML1.3～4.7地震的应力降位于0.02～7.26MPa范围内,超过90％的地震应...

The Spatial and Temporal Distribution of Source Parameters of Earthquakes in Changning Area,Sichuan Province

The source parameters of 442 earthquakes from December 2018 to July 2019 in Changning area of Sichuan Province are calculated by spectral ratio method,and the relationship between the source parameters and the spatiotemporal distribution characteristics of stress drop are analyzed. The earthquakes in the study area are mainly concentrated in the Changning M_S6.0 earthquake source area at the core of the Changning anticline and the Jianwu syncline shale gas mining area. We find that the stress drop of earthquakes with M_L1.3~4.7 is in the range of 0.02~7.26MPa, more than 90% of the earthquake stress drop is less than 2MPa,and the stress drop increases with the magnitude,but the relationship with the focal depth is not obvious. Before the occurrence of the Changning M_S6.0 earthquake,the stress drop of earthquakes in this area was generally at a low level. After the occurrence of the main earthquake,the stress drops of aftershocks increased significantly,and then decreased rapidly. In spatial distribution,the earthquakes with high stress drop are mainly concentrated in the northwest of Changning anticline,where several M_S>5.0 aftershocks have occurred. While the stress drop of earthquakes in Jianwu syncline is relatively low. The stress drops of earthquakes in the Jianwu syncline shale gas mining area is slightly lower than that of the Changning anticline area,but the difference is not significant.