基于随机振动模型的强地面运动数值模拟及其在广西灵山M6 3/4地震中的应用

Strong Ground Motion Simulation of the M6 3/4 Lingshan Guangxi Earthquake Base on Stochastic Finite Fault Modeling

摘要:

1936年4月1日广西灵山县平山镇东南罗阳山附近发生M6 3/4 地震,该地震是华南大陆自有地震记载以来发生的最大地震。本研究收集整理了灵山M6 3/4 地震的地质资料、活动断层探测最新成果等,选取适当的研究区域,利用随机振动有限断层模型计算区域内网格点的峰值加速度(PGA)及峰值速度(PGV)等参数,并且加入浅层横波速度结构V³⁰_s对地震动参数的影响,最终得到此次地震的地震动分布并分析了地震动特征。本研究将模拟结果与野外调查烈度数据和地震动衰减关系进行对比,结果显示模拟结果与调查烈度值和衰减关系在整体衰减特征、极震区的分布等方面均符合较好,模拟结果可为该地区未来地震危害性评估提供依据。本研究所使用的方法流程亦可应用于本地区地震烈度速报,为震后应急救援及决策指挥提供帮助。

Abstract:

On April 1,1936,an earthquake of M6 3/4 occurred near Luoyang mountain in the southeast of Pingshan town,Lingshan county,Guangxi. This event is the largest earthquake that has occurred in the South China continent since documental earthquake records are available. In this study,we collected and organized geological data and the recent research results related to this event. Then,we simulated strong ground motion parameters such as peak ground acceleration and peak ground velocity on each grid points within the area and incorporated the influence of shallow shear wave velocity structure V³⁰_s on the simulation results. Finally,we obtained the strong ground motion distribution of this earthquake and analyzed its characteristics. We compared the simulation results with field survey intensity data and attenuation relationships. The results showed that the simulation results are in good agreement with the survey intensity values and attenuation relationships in terms of overall characteristics and distribution of meizoseismal area. The simulation results of this study can provide a reliable basis for the risk assessment of future earthquake disaster in the region,and the technical methods used in this study can also be applied to rapid regional estimation of seismic intensity,providing assistance for emergency rescue and decision-making command after earthquakes.