2022年青海门源M_(s)6.9地震余震演化与地震触发  

The Aftershock Evolution and Earthquake Triggering of the 2022 Menyuan M_(s)6.9 Earthquake

作　　者：闫坤 王伟君[2] 寇华东 叶志鹏 YAN Kun;WANG Wei-jun;KOU Hua-dong;YE Zhi-peng(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]中国地震局地震预测研究所,北京100036

出　　处：《地震》2023年第1期15-32,共18页Earthquake

基　　金：中国地震局地震预测研究所基本科研业务专项项目(2020IEF0602,CEAIEF2022030202,2020IEF0504);国家自然科学基金项目(41574050,41674058)。

摘　　要：地震序列的时空演化有助于揭示地震成核过程和地震相互作用.本文采用双差定位方法对2009年以来门源地区的目录地震重新定位,并以其为模板,匹配扫描连续波形,完善2022年门源M_(s)6.9地震前后的活动图像.结果表明:2022年门源M_(s)6.9地震主要发生在托勒山北断裂南侧高角度南倾的走滑断裂上,无明显前震活动,是典型的主—余型序列;早期余震向主震东西两侧扩展,迁移距离与流逝时间呈对数关系,符合震后余滑扩散特征,并且西侧的迁移速率和地震强度高于东侧;冷龙岭断裂和门源地震发震断裂斜交,但它的地震活动与余震不同,这些活动在余震扩散前锋到达前开始,沿断层向东南方向迁移但很快受阻,直到5 d后Ms5.2地震发生后才继续南迁,最后终止于2016年门源Ms6.4地震余震扩散区的尾端附近.因此,两条断层上的地震时空演化反映了断层之间的相互作用,冷龙岭断裂的地震活动受2022年门源主震库仑应力变化影响而触发.The earthquake sequence's spatial-temporal evolution can help to reveal the earthquake nucleation process and the interaction between earthquakes.In this paper,we relocated earthquakes in the catalog since 2009 around the 2022 Menyuan M_(s)6.9 focal area with the HypoDD and used them as templates to match-filter re-scan continuous waveforms,building a more complete seismic activity map before and after the mainshock.The results show there was not obvious foreshock before the 2022 Menyuan mainshock and it was a typical mainshock-aftershock sequence.Most of aftershocks mainly occurred in a strike-slip fault on the south side of Tuoleshan-north fault,dipping to the south at a high angle.The early aftershocks expanded along strike to the east and west with a logarithm migration relationship between distance and the elapsed time,meeting the rule of the afterslip expansion.The Lenglongling fault oblique intersects with the mainshock's fault,and its seismicity is different from the aftershocks.The events in the Lenglongling fault occurred before the aftershock expansion front and migrated southeastward along the strike,but soon blocked.The migration continued again only after the Ms5.2 earthquake occurred 5 days later,and finally stopped near the end of the 2016 Menyuan aftershock zone.Therefore,the spatial-temporal evolution pattern of the earthquakes indicates the two faults interaction and the seismicity in the Lenglongling fault is probably triggered by the Coulomb stress change from the 2022 Menyuan mainshock.

关 键 词：2022年门源M_(s)6.9地震 微震检测 地震重定位 余震迁移 地震触发 

分 类 号：P315.7[天文地球—地震学]