芦山城区地震动放大特性:4.20芦山M_S 7.0级大地震余震观测分析  

Seismic ground motion amplification in Lushan downtown area: observation and analysis of aftershock data following the 4.20 Lushan M_S 7.0 earthquake

作　　者：余嘉顺[1,2] 韩超[1] 王绪本[1,2] 原健龙 付小波[1] 蓝星[1] 梁群[1] 周武[1] 杨宜海[1] 谭皓原 柳存喜 李梓汐 

机构地区：[1]成都理工大学地球物理学院,成都610059 [2]地球勘探与信息技术教育部重点实验室(成都理工大学),成都610059

出　　处：《地球物理学进展》2017年第3期1071-1079,共9页Progress in Geophysics

基　　金：四川省"百人计划"项目;国家自然科学基金项目(40841012);四川省科技厅科技支撑项目(2013SZ0173)联合资助

摘　　要：2013年4月20日,四川芦山发生M_S 7.0级大地震.地震发生后,我们应急进入震区考察,在城区范围内开展表层地震放大响应特性观测.通过在芦山城区范围内布置9个移动地震台站进行余震监测,记录到282个余震事件的三分量地震动数据,并选出8个记录质量好、噪声背景低、地震波形完整的余震数据进行分析.这8个地震均发生在以芦山城区为中心的15 km范围之内,震源深度10~17 km,震级1.5到3.7,全部为每个移动监测台站完整记录.从这些地震记录中截取其中的S波数据进行分析,计算每个台站每个地震记录分量的傅立叶振幅谱,利用南北与东西两个水平分量的数据合成一个综合的水平震动分量振幅谱函数,并将其与位于城西采石场基岩处参考观测点的台站记录数据进行比较.结果表明,芦山城区内各个观测点的地震动相对于参考点存在显著的放大效应,各个观测点的放大主频分布比较一致,多发生在5~6 Hz之间.而振幅放大效应则存在较大差异,放大倍数5~24不等.其中位于沫东镇的L07观测点的地震动放大效应特别突出,最大放大峰值高达24倍,对该处地震安全的威胁不容忽视.On April 20,2013,a major earthquake of MS 7. 0 occurred to Lushan,Sichuan,China. In an emergency response operation, we entered the epicentre area on a reconnaissance mission at the first time. In the following days,we deployed 9 mobile 3-component seismic stations in the Lushan downtown area to record aftershocks. From the 282 events recorded,we selected 8 events of good data quality for analysis of seismic ground motion amplification. The 8 events are of mag 1. 5 to 3. 7,occurred in depths of 10 - 17 km,within 15 km from the observation site. Swave parts of the recordings were used to calculate Fourier amplitude spectra. The spectra were then used to calculate spectral ratios of each observation site to a reference rock site located in a suburb to the west of the town. Our results demonstrated that the whole Lushan downtown area was dominated by significant seismic amplification of 5 - 24 times at the frequencies of 5 - 6 Hz. Within the downtown area covered by our observation network,a remarkable amplification factor of 24 from the observation site of L07 revealed a potential seismic safety threats to the area near the site.

关 键 词：芦山地震 芦山城区 余震监测 地震动 放大效应 

分 类 号：P315[天文地球—地震学]