辽宁地区Lg波衰减与场地响应的分区特征  

Distribution Characteristics of Lg-wave Attenuation and Site Response in Liaoning Area

作　　者：邵媛媛[1] 王岩[1] 郑勇[2,3] 杨士超[1] 钱蕊 贾丽华[1] SHAO Yuanyuan;WANG Yan;ZHENG Yong;YANG Shichao;QIAN Rui;JIA Lihua(Liaoning Earthquake Agency,Shenyang 110034,Liaoning,China;Institute of Geophysics&Geomatics,China University of Geosciences,Wuhan 430074,Hubei,China;Hubei Key Laboratory of Subsurface Multi-scale Imaging,China University of Geosciences,Wuhan 430074,Hubei,China)

机构地区：[1]辽宁省地震局,辽宁沈阳110034 [2]中国地质大学(武汉)地球物理与空间信息学院,湖北武汉430074 [3]中国地质大学(武汉)地球内部多尺度成像湖北重点实验室,湖北武汉430074

出　　处：《地震研究》2022年第4期552-559,共8页Journal of Seismological Research

基　　金：中国地震局地震科技星火计划青年项目(XH18014Y);中国地震局地球物理研究所基本科研业务费专项资助(DQJB21B34);自然学科基金(41874053)联合资助。

摘　　要：为探讨辽宁地区地质结构差异对Lg波衰减的影响,将辽宁地区分区为辽西隆起区、下辽河拗陷区、辽东隆起区3个构造单元,基于Lg波谱比法,利用2008—2017年辽宁数字地震台网记录到的308次M_(L)≥2.8~5.6地震的波形资料,在1~7 Hz频率范围内进行联合反演求解Lg波衰减参数与台站场地响应。结果表明:Lg波介质衰减特征分区差异明显,频率依赖指数η差异不大,东西、南北及垂直三分量的品质因子Q(f)在辽西隆起区为176.29~210.55、在下辽河拗陷区为75.18~141.81、在辽东隆起区为161.95~206.10,对应的η分别为0.39~0.9、0.55~0.73和0.50~0.69;各分区均为低Q_(0)、高η值,地震波衰减程度差异与区域地质构造特征一致;反演获得的台站场地响应幅值曲线较为平滑,下辽河拗陷地区的台站场地响应幅值大于辽西隆起区和辽东隆起区的场地响应幅值,说明辽宁地区Lg波介质衰减特征与区域浅层沉积层结构有关。In order to study the effect of the difference of geological structures on Lg-wave attenuation in Liaoning area,we divide the area into three tectonic zones:the Western Liaoning Uplift Region,the Eastern Liaoning Uplift Region,and the Xialiaohe Downwarping Region.Then,we select the waveform data of 308 earthquakes(M_(L)2.0-5.3)during 2007-2018 recorded by the Liaoning Digital Seismic Network,and use the Spectral Ratio method to conduct a joint inversion in the range of 1-7 Hz to calculate the parameters of Lg-wave attenuation and site response.The results show that the attenuation characteristics of Lg-wave are obviously different in these three tectonic regions,while the frequency-dependent indexes(η)have little difference.The Q(f)of the three components(UD,EW,NS)ranges in 176.29-210.55 in the Western Liaoning Uplift Region,in 75.18-141.81 in the Xialiaohe Downwarping Region,and in 161.95-206.10 in the Eastern Liaoning Uplift Region.Respectively,the frequency-dependent indexηranges from 0.39 to 0.90 in the Western Liaoning Uplift Region,from 0.55 to 0.73 in the Xialiaohe Downwarping Region,and 0.50 to 0.69 in the Eastern Liaoning Uplift Region.In the three regions the seismic-wave attenuation is consistent with the regional geological structure.The amplitude curves of the site response at stations are relatively smooth.The site-response amplitude in the Xialiaohe Downwarping Region is larger than that in the Western Liaoning Uplift Region and that in the Eastern Liaoning Uplift Region.This suggests that in Liaoning area the attenuation characteristics of Lg-wave is closely related to the structure of the shallow sedimentary layers.

关 键 词：LG波 衰减参数 场地响应 联合反演 辽宁地区 

分 类 号：P315.31[天文地球—地震学]