2022年1月8日青海门源M_(S)6.9地震震前变形特征分析  

Analysis of Deformation Characteristics before the Menyuan M_(S)6.9 Earthquake on January 8,2022 in Qinghai Province

作　　者：苑争一 赵静[1] 牛安福[1] Yuan Zhengyi;Zhao Jing;Niu Anfu(China Earthquake Networks Center,Beijing 100045,China)

机构地区：[1]中国地震台网中心,北京100045

出　　处：《中国地震》2022年第3期389-398,共10页Earthquake Research in China

基　　金：国家重点研发计划(2018YFE0109700);中国地震局2022年度震情跟踪定向工作任务(2022010213)共同资助。

摘　　要：2022年1月8日1时45分27秒青海海北藏族自治州门源县发生M_(S)6.9地震,基于大地测量资料详细分析震源区的构造运动、应变演化以及深部变形特征,对于发震机理及震后危险性分析具有重要的意义。本文利用1991—2016、2017—2020期中国大陆地区GNSS速度场,分析了青藏高原东北缘各断裂带的运动学特征、门源地震震中和周边区域的地壳应变及其动态演化特征;结合剖面投影和非线性拟合算法,定量计算了托莱山、冷龙岭断裂的滑动速率和闭锁深度,得到以下认识:①青藏高原东北缘不同断裂带的运动学特征差异较大,整体以地壳缩短运动为主,局部区域伴随旋转运动;②震中位于面膨胀率和最大剪应变率高值区的边缘,与前人关于强震地点的认识基本一致;③区域应变参数的时空演化过程显示,震中附近应变特征整体变化不大,表明断层可能处在孕震晚期阶段;④托莱山断裂带具有较高的滑动速率和闭锁深度,结合库仑应力的研究结果认为,该断裂未来一段时间的地震危险性仍值得关注。The Menyuan M_(S)6.9 earthquake occurred at 1:45:27 on January 8, 2022 in Haibei prefecture,Qinghai Province. Based on geodesic data,a detailed analysis of tectonic movement,strain evolution and deep deformation characteristics in the focal area is of great significance for earthquake mechanism and post-earthquake risk analysis. In this paper,the GNSS velocity field data of the Chinese mainland during 1991 to 2016 is used as the background to analyze the kinematic characteristics of each fault zone in the northeastern margin of the Tibetan Plateau after deducting Euler rotation. Based on GNSS velocity field and by using least square configuration method during 2017 to 2020, the crustal strain and its dynamic evolution characteristics in and around the epicenter were analyzed. With profile projector and using nonlinear fitting method,the depth of the slip velocity and fracture closure of Tuolaishan and Lenglong ridge fault were calculated,and we reached following results: ① In the northeastern margin of Qinghai-Tibet plateau,kinematics characteristics of different fault is various,i.e. the overall is predominant by shortenning crust movement,but local area with rotational deformation;② The epicenter is located at the edge of the region with high value of surface expansion and maximum shear strain rate,which is basically consistent with the previous understanding of strong earthquake location;③ The spatial-temporal evolution of regional strain parameters shows that compared with the background field,the overall strain characteristics near the epicenter have little change,indicating that the fault may be in the late seismogenic stage;④ The Tuolaishan Fault zone has a high slip rate and deep locking depth. Combined with the results of the Coulomb stress analysis,we considered that is still worth to pay attention to the seismic risk of the fault in the future.

关 键 词：门源 M_(S)6.9地震 GNSS运动学特征 应变参数演化 断层闭锁 

分 类 号：P315[天文地球—地震学]