基于背景噪声成像研究北京地区三维S波速度结构  

HIGH-RESOLUTION S-WAVE VELOCITY STRUCTURE OF BEIJING AREA USING AMBIENT NOISE TOMOGRAPHY

作　　者：吉宇 张广伟 任俊杰 何静 王肖薇 JI Yu;ZHANG Guang-wei;REN Jun-jie;HE Jing;WANG Xiao-wei(University of Chinese Academy of Sciences,Beijing 100049,China;National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China;School of Safety Engineering,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]中国科学院大学,北京100049 [2]应急管理部国家自然灾害防治研究院,北京100085 [3]中国矿业大学安全工程学院,徐州221116

出　　处：《地震地质》2025年第1期306-324,共19页Seismology and Geology

基　　金：国家自然科学基金(42074102,U2139201);应急管理部国家自然灾害防治研究院基本科研业务专项(ZDJ2020-09)共同资助。

摘　　要：特大城市地下三维速度结构对分析潜在灾害源和评价地震危险性具有重要的研究意义。文中利用北京地区28个宽频带地震台和109个短周期地震台的波形资料,采用背景噪声成像方法反演了北京地区上地壳和昌平南口-孙河断裂带周边浅部的三维S波速度结构。研究结果揭示北京的地下速度结构具有显著的横向非均匀性,断裂主要位于高、低波速异常的过渡带,其中凹陷区的低速异常反映了较深的沉积盖层,而构造隆起区的高速异常则反映了相对坚硬的古老岩层。基于小尺度密集台阵的反演结果显示,南口-孙河断裂断层面倾角较为陡立,控制了沙河凹陷的北侧边界,且沙河凹陷的沉积厚度远远深于上庄凹陷;另外,精细的三维速度模型为东北旺-小汤山隐伏断裂的存在提供了直接的地震学证据。文中研究表明,利用城市背景噪声可高效经济地获取地下三维速度结构,在识别主要地质构造单元和隐伏断裂等方面具有广阔前景。Beijing is located at the intersection of the Yanshan Mountains,Taihang Mountains,and the northwestern part of the North China Basin.This region has experienced multiple periods of crustal movement,forming a series of Cenozoic Basins exhibiting alternating uplifts and depressions.The intense tectonic activity has resulted in a relatively complex fault system,with the main directions of the faults being NE and NW.Notably,the Xixiadian Fault in the NE direction experienced an earth-quake with a magnitude of 8 in 1679.Meanwhile,the NW-oriented Nankou-Sunhe Fault offsets mul-tiple NE-oriented faults and directly passes through urban residential areas,making it an important active fault in Beijing.Although these intersecting faults have not experienced earthquakes of magni-tude 4 or higher in recent decades,small seismic events(M<4.0)still occur frequently.Furthermore,the thickness of Quaternary sedimentary layers in the Beijing area varies significantly.These relatively low-velocity sedimentary layers can cause seismic site effects such as amplitude amplification of seis-mic waves and increased vibration duration.Therefore,disaster detailed study of the three-dimen-sional velocity structure of the upper crust and depression areas in Beijing is of great significance for analyzing potential disasters and assessing seismic hazards.This study utilized continuous waveform data from 28 permanent seismic stations.The stations are distributed across the Beijing area,with an average inter-station distance of approximately 30km.This study's continuous constant waveform data spans from April 2022 to October 2022.For the Nankou-Sunhe Fault in the Changping area,we employed 109 short-period temporary seismic stations located around the fault zone.The seismic data is recorded from July 2,2022,to August 3,2022,over 33 days,with an average inter-station distance of approximately 2km.By applying the ambient noise tomography method,we successfully inverted the three-dimensional S-wave velocity structures of the upper crust for the Bei

关 键 词：背景噪声成像 三维速度结构 北京地区 南口-孙河断裂 沙河凹陷 

分 类 号：P315.2[天文地球—地震学]