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Title:: The Characteristics of Strong Motion Records of the 2022 Luding,Sichuan M_S6.8 Earthquake

作者:: 江鹏¹; 李萍萍¹; 李同林¹; 曾均¹; 王竞¹; 苏金蓉¹; 温瑞智²; (1.四川省地震局,四川成都 610041; 2.中国地震局工程力学研究所,黑龙江哈尔滨 150080)

Author(s):: JIANG Peng¹; LI Pingping¹; LI Tonglin¹; ZENG Jun¹; WANG Jing¹; SU Jinrong¹; WEN Ruizhi²; (1.Sichuan Earthquake Agency,Chengdu 610041,Sichuan,China)(2.Institute of Engineering Mechanics,China Earthquake Administration,Harbin 150080,Heilongjiang,China)

关键词:: 泸定地震; 强震动记录; 反应谱; 衰减关系

Keywords:: the Luding M_S6.8 earthquake; strong motion records; response spectrum; attenuation relation

分类号:: P315.914

DOI:: 10.20015/j.cnki.ISSN1000-0666.2023.0057

摘要:: 对地震监测台网获取的2022年四川泸定M_S6.8地震的1 799组强震动记录进行处理后计算地震动参数,利用克里金插值方法得到峰值加速度PGA、峰值速度PGV和加速度反应谱的空间分布图。结果表明:基准站、基本站和一般站记录到的地震动峰值依次增大,反映出局部地形和场地条件对地震动的放大作用。高烈度区仪器地震烈度和调查地震烈度较为一致,Ⅵ度以下区域仪器地震烈度和调查地震烈度等值线方向差异较大,反映出在震害不显著情况下两种烈度的对应关系不太理想。初步震相分析发现,近断层台站垂直方向峰值较大,多个台站记录到水平向速度大脉冲现象。基于基岩地震动峰值统计了本次地震的衰减特性,PGV随距离衰减相比中国地震动参数区划图更慢,综合震相特征认为本次地震更符合浅源地震的特点。为进一步分析地震动与震害的关系,选取了2个震害较为严重乡镇的强震动记录计算5%阻尼比的拟加速度反应谱,在设计地震反应谱特征周期Tg取值到1.5 s之间,台站记录反应谱值远超出设计地震反应谱,在部分周期区间还超出了罕遇地震设计反应谱值,体现出反应谱与震害较好的相关性。

Abstract:: At 12:52 on September 5,2022,an M_S6.8 earthquake occurred in Luding County,Sichuan Province,China.The Sichuan Earthquake Early Warning Network acquired 1 799 sets of seismic records.The acquisition of high-density strong motion records has great significance for the study of regional ground motion characteristics and source characteristics.In this paper,we calculate the ground motion related parameters of the strong motion records.Using the Kreging interpolation method,we obtain the spatial distribution maps of PGA,PGV,and acceleration response spectrum based on those related parameters.This shows that the peak values of ground motion recorded by the reference stations,the basic stations and the general stations increase successively,reflecting the amplification effect of terrain and site conditions.In the high intensity area,the intensity determined through strong ground motion instruments is consistent with the intensity determined through field investigation.While in the Ⅵ-degree area,there is a striking difference between the instrumental-intensity contour and the survey-intensity contour,which reflects that the instrumental intensity is not consistent with survey intensity in the area where the earthquake damage is light.The seismic phase analysis shows that the peak value in the vertical direction recorded by the stations near the fault is larger,and large horizontal velocity pulses are recorded at several stations.Based on the peak values of ground motion of bedrock,we analyze the attenuation characteristics of the Luding M_S6.8 earthquake.Compared with PGV proposed in the Seismic Ground Motion Parameters Zonation Map of China(GB18306—2015),PGV in this Luding earthquake event decays with distance more slowly.The characteristics of seismic phases show this earthquake is more consistent with the characteristics of shallow earthquakes.To further analyze the relationship between the ground motion and the earthquake damage,we select the strong motion records in two areas with severe earthquake damage,and calculate the pseudo-acceleration response spectrum of 5% damping ratio.In the period Tg-1.5 s,the acceleration response spectrum value exceeds the design response spectrum value.In some periods,the acceleration response spectrum value exceeds the response spectrum value of rare earthquakes.Response spectrum has a good correlation with earthquake damage.

《地震研究》[ISSN:1000-0666/CN:53-1062/P]

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