1932年昌马7.6级地震震源区及其邻近地区尾波衰减特征研究  

Characteristics of coda wave attenuation in the focal area of the 1932 Changma M 7.6 earthquake and its adjacent areas

作　　者：梁钊城 郭晓[1,2] 邹锐 LIANG Zhaocheng;GUO Xiao;ZOU Rui(Lanzhou Institute of Seismology,CEA,Lanzhou 730000,Gansu,China;Gansu Lanzhou Geophysics National Observation and Research Station,Lanzhou 730000,Gansu,China)

机构地区：[1]中国地震局兰州地震研究所,甘肃兰州730000 [2]甘肃兰州地球物理国家野外科学观测研究站,甘肃兰州730000

出　　处：《地震工程学报》2023年第3期532-539,共8页China Earthquake Engineering Journal

基　　金：甘肃省科技重大专项计划(21ZD4FA011)。

摘　　要：Q c值是描述地震波在地下衰减变化的重要物理参数之一,其大小能够反映该地区地震活动的强弱和地下介质非均匀性程度。基于Aki的单次散射模型,选用2008—2020年间昌马地震震源区及其周边区域5个固定数字化地震台站接收到的震中距小于100 km、M>2.0的1252次地震记录,计算分析该区域的尾波衰减特征。研究结果表明:(1)窗长为20 s、30 s和40 s的Q c值与频率f的衰减关系分别为Q c=(71.76±8)f^((1.10±0.04))、Q c=(103.83±17)f^((1.04±0.06))和Q c=(120.77±22)f^((1.00±0.06));(2)通过克里金插值绘制的Q c值空间分布图表明昌马地震震源区及其周边区域的Q c值分布与地质构造、地震活动性存在较明显的相关性;(3)研究区域的Q 0值较低,η值较高,与该区域构造活动性较强的特征相符。Q c is one of the important physical parameters to describe the attenuation of seismic waves underground.It can reflect the intensity of seismic activities and the degree of inhomogeneity of the underground media in a local area.In this work,the seismic records of 1252 M>2.0 earthquakes with epicenter distance less than 100 km received by five fixed digital seismic stations in the focal area of the 1932 Changma earthquake and its adjacent areas from^(2)008 to 2020 were selected to calculate and analyze the attenuation characteristics of code wave in this area using Aki's single scattering model.Results show that:(1)the attenuation relationship between frequency f and Q c values with window lengths of 20,30,and 40 s are Q c=(71.76±8)f^((1.10±0.04)),Q c=(103.83±17)f^((1.04±0.06)),and Q c=(120.77±22)f^((1.00±0.06)),respectively.(2)The spatial distribution diagram of Q c values plotted by Kriging interpolation indicates a correlation between the distribution of Q c values and the geologic structure and seismic activity in the focal area of the Changma earthquake and its adjacent areas.(3)The low Q 0 and highηin the study area are consistent with the strong tectonic activity in the region.

关 键 词：昌马地震 单次散射模型 尾波Q值 震源区 

分 类 号：P315.3[天文地球—地震学]