地震环境噪声成像中的地形影响校正  

Topographic correction in ambient noise tomography

作　　者：赵盼盼[1] Michel Campillo 陈九辉[1] 刘启元[1] 李昱[1] 郭飚[1] ZHAO PanPan;Michel Campillo;CHEN JiuHui;LIU QiYuan;LI Yu;GUO Biao(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Laboratoire de Geophysique Interne et de Tectonophysique,UniversitéJoseph Fourier,CNRS,Grenoble 38000,France)

机构地区：[1]中国地震局地质研究所,地震动力学国家重点实验室,北京100029 [2]Laboratoire de Geophysique Interne et de Tectonophysique,UniversitéJoseph Fourier,CNRS,Grenoble 38000,France

出　　处：《地球物理学报》2020年第10期3764-3774,共11页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41804055,41590862,41274060);国家重点研发项目(2017YFC1500103)联合资助.

摘　　要：以传统地震环境噪声面波成像方法研究地壳速度结构时,在一些极端的地形条件下,结果与真实结构会存在较大偏差.我们以地震波场三维正演模拟为基础,提出了一种地形校正方法.我们保留了传统噪声面波成像简单的两步反演法,在面波层析成像和一维速度结构反演的基础上,通过地震波场三维模拟近似估计地形和散射波场的影响,并据此校正瑞利波频散曲线,最终反演得到校正地形影响的S波速度结构.理论测试与在实际观测数据上的应用都证明了校正方法的有效性,同时也显示了地形校正的必要性.When the crustal velocity structure is studied by the classical ambient noise tomography,the results will biased under some extreme topographic conditions.We develop a topographic correction method based on the finite element simulation of the 3D seismic wavefield.We keep the simple two-step inversion process of the classical ambient noise tomography,which are surface wave tomography and 1D S wave velocity inversion,and approximately estimate the influence of topography and scattering by 3D simulation of seismic wavefield.Then we correct the dispersion curve of Rayleigh waves,and finally invert it to the corrected S-wave velocity structure.Both the theoretical test and the application to the actual observation data prove the validity of the correction method,and demonstrate the necessity of topography correction.

关 键 词：地震环境噪声 速度结构 地形校正 龙门山断裂带 

分 类 号：P315[天文地球—地震学]