2022年1月8日青海门源MS6.9地震同震形变场及地下位错反演

The Inversion of Co-seismic Deformation Field and Underground Dislocation of the Menyuan MS6.9 Earthquake on January 8, 2022 in Qinghai Province

摘要:

针对2022年1月8日青海门源M_S6.9地震，基于Sentinel-1A卫星的SAR影像获取了本次地震的同震形变场，并进行计算分析，运用SDM程序反演地下静态位错。初步结果如下：①本次地震震中位于蝴蝶状分布的形变图中心，抬升盘与下降盘之间的破裂迹线明显，破裂迹线长约24km，形变中心位于托莱山与冷龙岭断裂交汇处。②降轨数据显示，在断层区域视线向（LOS）形变量最小约-0.55m（远离卫星），最大约0.68m（靠近卫星）；升轨数据显示，在断层区域视线向（LOS）形变量最小约-0.49m（远离卫星），最大约0.42m（靠近卫星）。③对中国地震局发布的门源6.9级地震烈度图和本研究获取的地震形变图进行叠加分析，可以看出二者吻合度较高，地表有较明显形变所涉及区域约0.4万km²。④运用降轨InSAR数据反演得出地下最大位错量约3.29m，深度4.75km，在近地表位错破裂长度可达30km，地表有明显破裂的区域长约25km，与中国地震局科考工作每日情况的结果基本一致。

Abstract:

Based on the SAR image of sentinel-1A satellite for the M_S6.9 earthquake incident in Menyuan, Qinghai Province on January 8, 2022, we calculated the coseismic deformation field, and applied SDM program to retrieve the underground static dislocation. The preliminary results are as follows:① The epicenter of the earthquake is located in the center of the deformation map with butterfly shape, and the fracture trace between the lifting plate and the falling plate is obvious. The long of fracture trace is about 24km, with that deformation center is at the intersection of Tolaishan and Lenglongling faults. ② The data from down orbit shows that the shape variable(line of sight, LOS) in the fault area is at least -0.55m(away from the satellite) and at most about 0.68m(close to the satellite);The data from lifting orbit shows that the shape variable(line of sight, LOS) in the fault area is at least about -0.49m(away from the satellite) and at most about 0.42m(close to the satellite). ③ The superposition analysis of the intensity map of the Menyuan M_S6.9 earthquake released by the China Earthquake Administration and the deformation map of the earthquake shows that the coincidence between the intensity map and the deformation map is very high, and there exits an obvious deformation area about 4000km². ④ The maximum amount of underground dislocation is about 3.29m at the depth of 4.75km. The dislocation fracture near the surface is about 30km and the area with obvious fracture on the surface is about 25km, which is basically consistent with the field observation.