【摘要】 北京时间2025年1月7日9时5分西藏定日县(东经87.45??，北纬28.5??)发生了M_S6.8强震.为了深入研究此次地震同震过程的能量传播及其引起的强地面运动，本文利用基于远震波形和InSAR数据反演的运动学震源破裂模型，联合曲线网格有限差分法对该地震进行了三维地震波场数值模拟，并分析了地形起伏和浅部低速沉积层等因素对此次地震地表响应的影响.数值模拟结果表明，此次地震存在明显的断层上盘效应和破裂传播方向效应，峰值地表速度(PGV)高值区主要分布在震中区域及其北部的山地区域，涉及措果乡、长所乡等人口密集地区，与实际震害情况基本相符.基于远震波形和InSAR数据反演的震源破裂模型，其强地面运动模拟结果能够较好地解释观测台站数据的低频特征，在0.005～0.15 Hz频段范围与实际波形记录拟合良好.此外，地形和沉积层的影响分析表明，研究区域的地形起伏对地震波具有明显的放大效应；加之浅部沉积层在破裂传播方向上的放大作用，致使地震波能量进一步增强，从而引发更显著的地面震动.这可能是西藏定日M_S6.8地震造成显著震害的重要原因之一.更多还原

【Abstract】 At 9:05 Beijing time on January 7, 2025, a strong earthquake of M_S6.8 occurred in Dingri County,Xizang(87.45°E, 28.5°N). In order to deeply study the energy propagation during the coseismic process of this earthquake and investigate the strong ground motion caused by it, we adopted the kinematic source rupture model obtained using the teleseismic waveforms and InSAR data, and utilized the curved-grid finite difference method to conduct the 3D seismic wave field simulation of the earthquake. On this basis, the influences of topography and shallow low-velocity sediments on the surface seismic response are further discussed. The strong ground motion simulation results indicate that this earthquake exhibits obvious hanging wall effects and rupture directivity effects. The high peak ground velocity(PGV) areas are mainly distributed at the epicenter and the mountainous region to the north of it, involving densely populated areas such as Cuoguo and Changsuo township, which is consistent with the actual damage situation. The strong ground motion simulation results based on kinematic rupture model inverted from the teleseismic waveform and the InSAR data can well explain the low-frequency characteristics of the data observed at the real stations. The modeled records have good consistency with the observed waveforms at the frequency range of 0.005～0.15 Hz. In addition, analysis on the impact of topography and shallow sediments demonstrates that the rugged topography undulation in the study area has a significant amplification effect on the seismic waves. Moreover, the low-velocity sediments can also enhance the seismic energy along the rupture direction and lead to larger ground motion. This may be one of the important reasons for the serious impacts of the Xizang, Dingri M_S6.8 earthquake.更多还原