随机有限断层法的俯冲带板内地震动模拟  

Simulation of ground motions caused by subduction slab earthquakes based on stochastic finite fault method

作　　者：林德昕 马强[1,2] 陶冬旺 马完君 解全才 刘名吉[1,2] LIN Dexin;MA Qiang;TAO Dongwang;MA Wanjun;XIE Quancai;LIU Mingji(Key Laboratory of Earthquake Engineering and Engineering Vibration,Institute of Engineering Mechanics,China Earthquake Administration,Harbin 150080,China;Key Laboratory of Earthquake Disaster Mitigation,Ministry of Emergency Management,Harbin 150080,China)

机构地区：[1]中国地震局工程力学研究所地震工程与工程振动重点实验室,哈尔滨150080 [2]地震灾害防治应急管理部重点实验室,哈尔滨150080

出　　处：《哈尔滨工业大学学报》2023年第10期103-113,共11页Journal of Harbin Institute of Technology

基　　金：中国地震局工程力学研究所基本科研业务专项(2021B08,2016A03);国家自然科学基金(5150082083)。

摘　　要：为明确随机有限断层法在俯冲带板内地震动模拟中的适用性,以2021年日本千叶M j6.1俯冲带板内地震为例,使用该方法模拟了震中范围100 km内25组KiK-net台站井上和井下记录,并分析了模拟与观测记录的频谱、持时、峰值和空间分布等地震动特征。结果表明:模拟与观测记录的5%阻尼比拟加速度反应谱(A_(ps))在0.1~10 Hz频带范围内吻合较好;基于70%能量持时模型的模拟记录在强震动段和持时上与观测记录匹配良好;井上台模拟与观测记录的地表峰值加速度(A_(pg))接近,且两者A_(pg)衰减特征基本一致;模拟和观测记录所得A_(pg)等值线相似。此外,将模拟和观测记录与现有日本俯冲带板内地震动衰减关系式(Zhao16)进行了比较,发现Zhao16的A_(pg)预测值普遍出现高估,其A_(ps)预测值在低频和高频分别出现一定程度的低估和高估,这可能与研究区域的盆地效应和软土层有关。研究结果为随机有限断层法模拟俯冲带板内地震动的适用性提供了依据,进而为探索将该方法应用于中国具有相似俯冲带构造的地区提供参考。In order to verify the applicability of the stochastic finite fault method in simulating ground motions caused by subduction slab earthquakes,the 2021 Chiba,Japan M j 6.1 subduction slab earthquake was taken as an example,and a total of 25 sets of surface and borehole station records within a range of 100 km around the epicenter were obtained from KiK-net and simulated by the stochastic finite fault ground motion method.The ground motion characteristics such as spectrum,duration,peak value,and spatial distribution of simulated and observed records were analyzed.Results show that the simulated and observed response spectra of pseudo-spectral acceleration(A_(ps))with 5%damping ratio were well matched in the band range of 0.1–10 Hz.The simulated records of duration model based on 70%energy duration were consistent with the observed records in the strong motion section.The simulated and observed peak ground acceleration(A_(pg))from the surface stations were in good agreement,and the A_(pg)attenuation characteristics were basically the same.The A_(pg)contours based on the simulated records were very similar to the observed A_(pg)contours.In addition,the simulated results and observed records were compared with the results of commonly used ground motion prediction equations(Zhao16)for subduction slab earthquakes in Japan.Results show that the A_(pg)prediction of Zhao16 was generally overestimated,and the A_(ps)prediction was underestimated and overestimated to some extent at low and high frequencies respectively,which may be caused by the basin effect and soft soil layer in the study area.The research results can provide basis for the applicability of the stochastic finite fault method in ground motions caused by subduction slab earthquakes,and will offer further reference for exploring the application of the method to areas with similar tectonics in China.

关 键 词：2021日本千叶地震 随机有限断层法 地震动模拟 俯冲带衰减关系 俯冲带板内地震 

分 类 号：P315.9[天文地球—地震学]