基于经验格林函数法的2021年M_(S)6.4漾濞地震近场强震动模拟  

THE EMPIRICAL GREEN'S FUNCTION-BASED SIMULATION OF NEAR-FIELD STRONG GROUND MOTIONS OF THE 2021 YANGBI EARTHQUAKE(M_(S)6.4),YUNNAN,CHINA

作　　者：吴浩 入倉孝次郎 林国良[3] WU Hao;IRIKURA Kojiro;LIN Guo-liang(School of Civil Engineering,Shandong Jianzhu University,Jinan 250101,China;Disaster Prevention Research Center,Aichi Institute of Technology,Toyota 4700392,Japan;Yunnan Earthquake Agency,Kunming 650224,China)

机构地区：[1]山东建筑大学,土木工程学院,济南250101 [2]爱知工业大学,地域防灾研究中心,日本丰田4700392 [3]云南省地震局,昆明650224

出　　处：《地震地质》2023年第4期864-879,共16页Seismology and Geology

基　　金：国家自然科学基金(51878396);山东省高等学校“青创科技计划”(2019KJG015)。

摘　　要：由于震中附近强震台分布不均,文中联合使用近场2个国家强震动观测台网的强震台和7个云南地震预警台网烈度台的强震记录,采用经验格林函数法构建了特性化震源模型,并利用此模型对近场强震动进行了模拟。结果表明:烈度台的记录可与强震台的记录联合,共同作为强震动模拟的对象,但应注意区分二者的有效频带;在0.20~30.0Hz频带,在53YBX台处的NS分量上,模拟结果的伪加速度反应谱较好地再现了0.1s处的峰值,在EW分量上,合成的速度波形虽然幅值较低,但较好地再现了速度脉冲波段;在53DLY台处的合成波形较好地再现了约2s的长周期地震动;在0.50~30.0Hz频带,合成波形和反应谱与信噪比较高的烈度台的记录较为一致。文中确定的用于模拟强震动的特性化震源模型由一个强震动生成域构成,其面积和相应的短周期范围内加速度震源谱的水平段幅值与地震矩的关系均遵循经验标度律。Both short(0.1s)and long(1~2s)periods ground motions were observed at the near-field strong-motion stations during the mainshock of the 2021 M_(S)6.4 Yangbi earthquake,Yunnan.As there are only two strong-motion stations observed by the National Strong Motion Observation Network System of China in the near-field,the strong ground motion records at seven intensity stations observed by the Local Earthquake Early Warning Network of Yunnan Province are combined to construct the characterized source model with the empirical Green's function method.The broadband strong ground motions in the near-field are synthesized by using the characterized source model.We firstly select out an MW4.3 foreshock as the empirical Green's function event.Then,we calculate the observed source spectral ratios at seven stations assuming that the source spectrum obeys to theω-2 law.The results show that both the observed source spectral ratios in the frequency of 0~0.2Hz at strong-motion stations and 0~0.5Hz at intensity stations deviate from theω-2 law assumption.Thus,we determine the size of the sub-fault by fitting the observed source spectral ratio averaged at two strong-motion stations to the theoretical source spectral ratio in the frequency of 0.2~30.0Hz.Taking two strong-motion stations and four intensity stations as the target stations,we adopt the simulated annealing method to determine the optimal parameters required for ground motion synthesis,such as proportional parameters N and C,the position of rupture starting point within the strong motion generation area,rupture velocity,and rise time,when the misfit function between synthesized and observed ground motions reach the minimum at the target stations.We fix the rupture starting point at the hypocenter of the mainshock,and determine N=4,C=3.69,rupture velocity of 2.5km/s,and rise time of 0.56s.In this study,the characterized source model used for the strong ground motion simulation consists of one strong motion generation area which is 5.4km along the strike direction and 5.4k

关 键 词：经验格林函数法 强震台 烈度台 强震动模拟 强震动生成域 

分 类 号：P315.9[天文地球—地震学]