2021年云南漾濞地震序列中强(M_(S)≥5.0)地震强震动特征  

Strong-motion characteristics in moderate-to-strong(M_(S)≥5.0)earthquakes of the 2021 Yangbi Yunnan earthquake sequence

作　　者：强生银 王宏伟[1,2] 温瑞智 任叶飞[1,2] 崔建文 QIANG Shengyin;WANG Hongwei;WEN Ruizhi;REN Yefei;CUI Jianwen(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;Yunnan Earthquake Agency,Kunming 650224,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,黑龙江哈尔滨150080 [2]地震灾害防治应急管理部重点实验室,黑龙江哈尔滨150080 [3]云南省地震局,云南昆明650224

出　　处：《西安建筑科技大学学报（自然科学版）》2023年第2期242-248,共7页Journal of Xi'an University of Architecture & Technology(Natural Science Edition)

基　　金：中国地震局工程力学研究所基本科研业务费专项资助项目(2020C05)。

摘　　要：2021年云南漾濞地震序列包括4次M_(S)≥5.0中强地震(M_(S)5.6前震、M_(S)6.4主震、M_(S)5.0和M_(S)5.2余震),这四次中强地震中强震动台站和地震烈度速报台共获得强震动记录近千组,尤其近场记录,这些记录为分析强震动特征提供了良好契机.本文选取550组高质量的强震动记录,经过严格的记录数据处理后,采用插值方法给出了M_(S)6.4主震峰值地面加速度(PGA)和峰值地面速度(PGV)的空间分布,空间分布受震源破裂方向性和局部场地效应的影响,利用破裂方向性系数C d表示震源破裂方向性相关的强震动峰值参数的方位角相关性,反演给出了四次地震的震源破裂方向性特征,其中M_(S)6.4主震为沿NNW-SSE走向的双向非对称破裂事件,优势破裂方向为SSE,在优势破裂方向上的破裂约占整个破裂长度的85%.将四次地震PGA、5%阻尼比拟加速度反应谱(PSA)与ASK14预测模型的预测中位值进行对比,事件间残差均为负值,表明四次漾濞中强地震中地震动的震源效应相对较弱,短周期地震动的震源效应可能与地震类型相关,震源效应M_(S)5.6前震>M_(S)6.4主震>M_(S)5.2余震,事件间残差随距离增大呈上升趋势,表明漾濞地震发震区及附近区域的非弹性衰减相对较弱.The 2021 Ynagbi,Yunnan earthquake sequence consists of four moderate-to-large earthquakes with M_(S)≥5.0,i.e.,the M_(S)5.6 foreshock,M_(S)6.4 mainshock,M_(S)5.0 and M_(S)5.2 aftershock.In the four events,the strong-motion and seismic intensity stations totally obtained about 1000 free-field three-component strong-motion recordings,which provided excellent chance for investigating strong-motion characteristics.In this paper,550 sets of high quality strong motion records are selected.After rigorous processing of the recorded data,the spatial distribution of peak ground acceleration(PGA)and peak ground velocity(PGV)of M_(S)6.4 main shock are given by interpolation method.The spatial distribution is affected by the rupture directivity and local site effect.The source rupture directivity coefficient C d is utilized to represent the dependency of strong-motion peak parameters on the azimuth,and the parameters of source rupture directivity are estimated for the four Yangbi events.The M_(S)6.4 mainshock is a bidirectional asymmetric rupture event along the NNW-SSE direction.The dominant rupture direction is SSE,and the rupture in the dominant rupture direction accounts for about 85%of the total rupture length.Comparing the predicted median values of the four earthquakes PGA,5%damping psedu-acceleration response spectrum(PSA)and the ASK14 prediction model,the residuals between events are negative,indicating that the source effect of ground motion in the four Yangbi moderate-strong earthquakes is relatively weak.The source effects on short-period ground motions approximately show the dependence on earthquake type,i.e.,M_(S)5.6 foreshock>M_(S)6.4 mainshock>M_(S)5.2 aftershock.The increasing trend of inter-event residuals with the increasing distance indicates the weaker anelastic attenuations in the study region than those described by the ASK14 model.

关 键 词：漾濞地震序列 强震动特征 破裂方向性 震源效应、非弹性衰减 

分 类 号：P315.9[天文地球—地震学]