近震远台的走时层析成像方法研究  

Seismic traveltime tomography using earthquakes in study domain and stations at teleseismic distances

作　　者：章浩东 刘少林 杨顶辉[3] 申文豪 徐锡伟 李小凡 杨树新 潘阳 ZHANG HaoDong;LIU ShaoLin;YANG DingHui;SHEN WenHao;XU XiWei;LI XiaoFan;YANG ShuXin;PAN Yang(National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China;Shanghai Sheshan National Geophysical Field Observation and Research Station,Shanghai 201602,China;Department of Mathematical Sciences,Tsinghua University,Beijing 100084,China;Institute of Geophysical and Geomatics,China University of Geosciences,Wuhan 430074,China)

机构地区：[1]应急管理部国家自然灾害防治研究院,北京100085 [2]上海佘山地球物理国家野外科学观测研究站,上海201602 [3]清华大学数学科学系,北京100084 [4]中国地质大学地球物理与空间信息学院,武汉430074

出　　处：《地球物理学报》2023年第10期4206-4223,共18页Chinese Journal of Geophysics

基　　金：上海佘山地球物理国家野外科学观测研究站开放基金项目(SSOP202203和SSOP202108);国家自然科学基金项目(42174111和42064004);北京市自然科学基金项目(8222033)联合资助。

摘　　要：远震层析成像是研究壳幔三维结构的重要手段.虽然远震层析成像已成功应用于台站分布较好区域的地下结构成像研究,但地球上有些关键构造区域缺乏地震台站,以至于难以应用远震层析成像研究壳幔结构.为了实现台站匮乏构造区的远震层析成像,根据互易性定理,将传统远震成像中研究区域周边远震激发地震波、区域内台站记录地震信号(远震近台)的观测系统,变换成研究区域内地震激发地震波、周边远震距离范围内台站接收信号(近震远台)的观测系统,实现近震远台的远震层析成像.首先,本文给出了基于近震远台的走时层析成像方法的基本原理和实现步骤.随后,分析了影响成像结果的三个主要因素:射线覆盖密度、走时拾取误差和震源不确定性.最后,以日本俯冲带为例,利用近震远台的成像方法反演实际数据,得到日本俯冲带上地幔速度结构,实际算例证实了该成像方法的有效性.Teleseismic tomography is an important technique to investigate the 3-D crust and mantle of the Earth.Although teleseismic tomography has been successfully applied to image subsurface structures of tectonic zones with the relatively well distribution of stations,it is difficult to study the crust and mantle structures in some tectonic zones with a scarcity of seismic stations.In order to perform teleseismic tomography in such zones,we conducted a teleseismic tomography method by employing a new observation system.We transform the traditional observation system into a new one based on the reciprocity theorem.The traditional observation system of teleseismic tomography relies on seismic waves excited by teleseismic earthquakes around the study area and seismic signals recorded by stations in the study area.While the new observation system is that regional earthquakes inside the study area excite seismic waves and stations outside the study area at teleseismic distances record seismic signals.This article mainly contains three parts.First,we introduce the main principles and the processes of the application of the new teleseismic tomography method.Second,we analyze three influencing factors,which are ray coverage,picking error and source uncertainty.Third,we apply the new teleseismic tomography method to the Japan subduction zone by the inversion of real seismic traveltime data,and obtain the upper mantle velocity structure of the subduction zone.This real data tomography demonstrates the effectiveness of the developed method in this article.

关 键 词：远震层析成像 互易性定理 不确定性分析 上地幔速度结构 日本海 

分 类 号：P315[天文地球—地震学]