江西寻乌地区及邻区浅层三维速度结构及其孕震构造初探  

Shallow 3-D velocity structure and its implications for seismogenic structure in the Xunwu(Jiangxi)region and its adjacent areas

作　　者：王向腾 谢超灵 邓中豪 邓居智[1] 章双龙 邹勇军 包丰 姚振岸 李志伟 WANG XiangTeng;XIE ChaoLing;DENG ZhongHao;DENG JuZhi;ZHANG ShuangLong;ZOU YongJun;BAO Feng;YAO ZhenAn;LI ZhiWei(National Key Laboratory of Prospecting,Mining and Remote Sense Detecting on Uranium Resources,East China University of Technology,Nanchang 330013,China;Jiangsu Donghai Continental Deep Borehole Crustal Activity National Observation and Research Station,Beijing 100037,China;State Key Laboratory of Geodesy and Earth's Dynamics,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences,Wuhan 430077,China;Beijing Institute of Satellite Environmental Engineering,Key Laboratory of Reliability and Environmental Engineering Technology,Beijing 100094,China;Jiangxi Institute of Coal Geology for Exploration Research,Nanchang 330001,China)

机构地区：[1]东华理工大学铀资源探采与核遥感全国重点实验室,南昌330013 [2]江苏东海大陆深孔地壳活动国家野外科学观测研究站,北京100037 [3]中国科学院精密测量科学与技术创新研究院,大地测量与地球动力学国家重点实验室,武汉430077 [4]北京卫星环境工程研究所可靠性与环境工程技术重点实验室,北京100094 [5]江西省煤田地质勘察研究院,南昌330001

出　　处：《地球物理学报》2024年第12期4651-4665,共15页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42130811,41904044,42004113,42174076);江西省自然科学基金(2023BAB213079,20242BAB25190);江西省科技创新高端人才项目(DHSQT42023001);江西省地质局青年科学技术带头人培育项目(2022JXDZKJRC05);湖南省教育厅科学研究项目(21B0566);大地测量与地球动力学国家重点实验室开放基金(SKLGED2020-4-1-E);东华理工大学研究生创新基金(S202310405017,YC2024-S470和DHYC-202416)共同资助。

摘　　要：寻乌地区位于邵武—河源断裂带中段,发生过多次破坏性地震,其中包括1806年M6地震以及1941年M~5.75地震和1987年M~5.5地震群,是邵武—河源断裂带地震活跃的区域之一,也是江西省防震减灾重点关注区域之一.获取该地区的浅层速度结构有助于提高地震定位以及震动图计算的精度.然而,该地区固定台网稀疏,加之研究区NW以及NE向断层交错发育,增加了地震构造环境研究的难度.本文基于寻乌地区布设的密集台阵,获得了持续一个多月的连续波形数据,计算了台站对噪声互相关,并提取了瑞利面波相速度(0.5~6 s)信息,进而采用面波层析成像方法反演了寻乌以及邻区的地壳浅部6 km速度结构.相速度以及S波速度反演结果均很好地展示了断层的浅部空间特征、断陷盆地以及岩体的分布.约3 km深的浅层低速带揭示了会昌和寻乌等断陷盆地的分布,也与邵武—河源断裂带在周田附近"S"型急转弯有很好的对应关系,进一步说明区域断裂带对盆地发育的控制作用.区域典型地震集中在高低速结构过渡区,S波速度高低速变化显示了NW走向断层在深度上的空间展布情况,推测NW向断裂主导了研究区域的地震.Situated within the Shaowu-Heyuan fault zone,the Xunwu area has experienced several moderate earthquakes,notably the M6 earthquake in 1806,the M~5.75 earthquake in 1941,and a swarm of M~5.5 earthquakes in 1987.It is one of the seismically active regions along the Shaowu-Heyuan fault zone,and also one of the key areas for earthquake prevention and mitigation in Jiangxi province.The shallow subsurface velocity structures in this area help improve the accuracy of earthquake location and seismogram calculation.However,the sparse seismic network in the region,coupled with the complex development of NW and NE-trending faults,has posed significant challenges to studying the seismogenic environment.In this study,based on continuous waveforms observed by a dense array across Xunwu and its neighboring areas,we computed noise cross-correlation between station pairs and extracted Rayleigh wave(0.5~6 s).The surface wave tomography method was applied to invert the velocity structure up to 6 km depth of the study area.Both phase velocity and S-wave velocity reveal the shallow spatial characteristics of faults,graben basins,and lithological structure.The shallow low-velocity zone approximately 3 km deep reveals the distribution of graben basins such as Huichang and Xunwu and exhibits a strong correspondence with the'S'-shaped sharp turn of the Shaowu-Heyuan fault zone near Zhoutian,which highlights the influence of regional fault zones on the evolution of the basin.Earthquakes in the region predominantly occur in the transition zone between high and low-velocity structures.Variations of S-wave velocity demonstrate the spatial distribution of NW-trending faults,suggesting that NW-oriented faults are the primary contributors to the seismicity in the study area.

关 键 词：寻乌地区 噪声成像 密集台阵 浅层速度 邵武—河源断裂 

分 类 号：P315[天文地球—地震学]