摘要
2022年3月17日新疆皮山发生M_(S)5.2地震,时隔83天,于6月8日再次发生M_(S)5.0地震,2次地震相距约9 km。M_(S)5.2地震前10天,震区出现小震群活动,三十里营房地震台记录到671次前震活动,序列活动表现出震群型特征。利用CAP方法计算皮山M_(S)5.2、M_(S)5.0地震的震源机制解,显示2次地震破裂类型差异较大,其中M_(S)5.2地震为逆冲型,M_(S)5.0地震为正断兼走滑型。根据2022年皮山5级震群序列特征及2次主要地震事件破裂方式的差异,结合震中附近构造特征,探讨此次震群活动的构造复杂性,认为皮山震群发生在天神达坂断裂和康西瓦断裂之间的次级断裂上,推测在NS向构造应力作用下,康西瓦断裂南北两侧的左旋滑移量部分被西昆仑前缘的逆冲断裂系所吸收,由于构造方式的差异及应力分配的不均匀,其EW向运动速率在不同区段存在一定差异,在局部地区形成近EW向的差应力,进而产生一些拉张性质的破裂。
On March 17,2022,a magnitude 5.2 earthquake occurred in Pishan,Xinjiang.After 83 days,another earthquake with magnitude 5.0 occurred in Pishan on June 8,2022,these two earthquakes were about 9km apart.In addition,10 days before the Pishan M_(S)5.2 earthquake,small earthquake swarm activity began to appear in the earthquake area.A total of 671 foreshock activities were recorded by a single station in SSL,and the sequence activity showed the characteristics of earthquake swarm type.The focal mechanism of the two M 5 earthquakes was calculated by the CAP method.The rupture type of the Pishan M_(S)5.2 earthquake was thrust type,and the focal mechanism of the Pishan M 5.0 earthquake was normal fault and strike slip type.The rupture types of the two earthquakes were quite different.According to the sequence characteristics of the Pishan M 5 earthquake swarm in 2022,the difference of the rupture modes of the two main earthquake events in the sequence,and the structural characteristics near the epicenter,the tectonic complexity of the earthquake swarm activity is discussed.It is considered that the Pishan earthquake swarm occurred on the secondary fault between Tianshen Daban fault and Kangxiwar fault.It is speculated that under the action of NS-trending tectonic stress,part of the left-lateral slip on the north and south sides of the Kangxiwa fault was absorbed by the thrust fault system at the front of West Kunlun.There is a certain difference in the east-west movement rate in different sections,and a near-EW-direction differential stress is formed in the local area,which in turn produces some tensile fractures.
作者
李金
史勇军
孙昭杰
LI Jin;SHI Yongjun;SUN Zhaojie(Xinjiang Pamir Intracontinental Subduction National Field Observation and Research Station,Urumqi 830011,China;Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,China;Urumqi Institute of Central Asia Earthquake,China Earthquake Administration,Xinjiang Uygur AutonomousRegion 830011,China;Kashi Earthquake Monitoring Center Station,Earthquake Agency of Xinjiang Uygur Autonomous Region,XinjiangUygur Autonomous Region 844000,China)
出处
《地震地磁观测与研究》
2022年第4期175-185,共11页
Seismological and Geomagnetic Observation and Research
基金
中国地震局地震科技星火计划(项目编号:XH21042)
新疆地震科学基金(项目编号:202007)
新疆维吾尔自治区重点研发课题(项目编号:2022B03001-1)
新疆维吾尔自治区自然科学基金(项目编号:2020D01A83)
新疆地震局科技创新团队计划(项目编号:XJDZCXTD2020-3)。
关键词
皮山5级震群
前震序列
震源机制解
西昆仑
Pishan M 5 earthquake swarm
foreshock sequence
focal mechanism solution
west Kunlun
