2022年青海门源M_(S)6.9地震余震的空间迁移特征  

Spatial migration characteristics of the aftershock sequence of the Menyuan,Qinghai M_(S)6.9 earthquake in 2022

作　　者：刘泽民 张广伟 梁姗姗[2] 邹立晔[2] LIU Zemin;ZHANG Guangwei;LIANG Shanshan;ZOU Liye(National Institute of Natural Hazards, MEMC, Beijing 100085, China;China Earthquake Network Center, Beijing 100045, China)

机构地区：[1]应急管理部国家自然灾害防治研究院,北京100085 [2]中国地震台网中心,北京100045

出　　处：《地震工程学报》2022年第2期475-487,共13页China Earthquake Engineering Journal

基　　金：应急管理部国家自然灾害防治研究院基本科研业务专项(ZDJ2021-12,ZDJ2019-16)。

摘　　要：精确识别和定位中强地震序列中的微震事件对于准确判定发震构造具有重要的意义。文章对2022年1月8日发生在青藏高原东北缘的青海门源M_(S)6.9地震序列进行精定位及微震检测研究。首先运用双差定位法对2022年1月8—16日由中国地震台网中心记录的1010个门源地震序列原始目录进行重定位,得到404个精定位地震目录。分别采用原始地震目录(CENC)和双差重定位目录(HypoDD),对震源区150 km范围内9个台站的连续波形数据进行微震检测。结果表明,基于CENC目录识别的余震个数是原始目录地震数量的3.0倍,基于HypoDD目录识别的地震个数是原始目录的2.1倍,是HypoDD目录的5.8倍;两种地震目录的微震检测均使得ML震级完备性从1.7级降低至1.1级。新的地震目录空间位置显示,主震发生后余震主要沿托莱山断裂向西侧扩展,8分钟以后,在托莱山断裂和冷龙岭断裂均发生破裂。根据本研究获取的更高空间分辨率的地震序列,同时结合震源机制解,认为2022年门源M_(S)6.9地震初始破裂位于近E-W向的托莱山断裂,并触发了NW-SE向的冷龙岭断裂,地震的发生主要受到印度板块北东向的长期挤压作用,应力不断积累最终断层失稳而引发地震。Accurate detection and location of microseismic events in the moderate-strong earthquake sequence is of great significance to determine the seismogenic structure.On January 8,2022,an M_(S)6.9 earthquake occurred in Menyuan County of Qinghai Province,which is located at the northeastern margin of the Tibet Plateau.To investigate the seismogenic fault of this earthquake,we first used the double difference location method to relocate the catalogue events from China Earthquake Network Center(CENC),which includes 1010 earthquakes from January 8 to January 16,2022,and then obtained the precise location of 404 earthquakes.The original seismic catalogue(CENC)and double difference relocation catalogue(HypoDD)were then used to detect micro-earthquakes from the continuous waveform data of 9 stations within 150 km of the source region.The results showed that the number of aftershocks identified based on CENC catalogue is 3.0 times more than that of the original catalogue,and the number of aftershocks identified based on HypoDD catalogue is 2.1 times more than that of the original catalogue and 5.8 times more than that of the HypoDD catalogue.The micro-earthquake detection of the two earthquake catalogues reduced the completeness of ML from 1.7 to 1.1.The spatial location of the new earthquake catalogue showed that,the aftershocks mainly spread westward along the Tuolaishan fault.And eight minutes after the mainshock,both the Tuolaishan fault and the Lenglongling fault ruptured.Based on the high resolution earthquake locations and the focal mechanism solution,we suggested that the initial rupture of the 2022 Menyuan M_(S)6.9 earthquake is located in the nearly EW-trending Tuolaishan fault.The occurrence of the earthquake is mainly due to the long-term extrusion of the Indian plate in the northeastern direction.

关 键 词：门源M_(S)6.9地震 托莱山断裂 微震检测 地震时空迁移 发震构造 

分 类 号：P315.2[天文地球—地震学]