2022年1月8日青海门源M_(S)6.9地震强地面运动模拟及烈度分布估计

Strong ground motion simulation and intensity distribution estimation for the M_(S)6.9 Menyuan,Qinghai,earthquake on 8 January 2022

2022年1月8日青海省海北藏族自治州门源回族自治县发生M_(S)6.9地震。门源地震序列的重定位结果认为门源地区还存在一定的应力积累,未来该地区具有发生强震的可能。本文结合震源区地形数据、三维速度结构,根据门源地震震源破裂过程的初步结果,采用曲线网格有限差分方法模拟了门源地震的波场传播过程,得到烈度分布。结果表明:沿平行断层走向方向的地震动衰减明显小于垂直断层走向方向;门源地震的最大烈度为Ⅷ度,位于震源破裂起始点附近区域,理论烈度与野外调查的地震烈度分布基本一致;受强地面运动方向性效应和起伏地表的影响,地震灾害主要沿发震断层的WNW方向和ESE方向集中分布。

A MS6.9 earthquake occurred at Menyuan County,Haibei Prefecture,Qinghai Province on 8 January 2022.Relocation results of the Menyuan MS6.9 earthquake sequence suggest that there is still a possibility for another strong earthquake in Menyuan area.Based on topography data and three-dimensional velocity structure in the source zone,together with the preliminary result about the source rupture process of Menyuan earthquake,we simulated seis-mic wave propagation of Menyuan MS6.9 earthquake by curvilinear-grid finite difference method,and obtained seismic intensity distribution accordingly.The simulated results show that the ground motion attenuation along the direction of fault strike is significantly smaller than that along the direction of fault dip.The maximum seismic intensity caused by Menyuan MS6.9 earthquake is aboutⅧdegree,and located in the vicinity of the rupture initial point.Theore-tical intensity distribution is roughly consistent with the seismic intensity distribution from field surveys.Affected by the directional effects of strong ground motion and undulated topography,earthquake disasters mainly concentrated in the WNW and ESE directions of the seismic fault.