甲烷震源和密集台阵观测研究粤港澳大湾区中心城区浅部P波三维速度结构  

Three-dimensional shallow velocity structure beneath the central area of Guangdong-Hong Kong-Macao Greater Bay Area revealed by methane source and dense array

作　　者：王力伟[1,2,3] 张云鹏 王伟涛[3,4] 刘世烁 叶秀薇[1,2] 杨微 徐善辉 马晓娜[3,4] WANG LiWei;ZHANG YunPeng;WANG WeiTao;LIU ShiShuo;YE XiuWei;YANG Wei;XU ShanHui;MA XiaoNa(CEA Key Laboratory of Earthquake Monitoring and Disaster Mitigation Technology,Guangdong Earthquake Agency,Guangzhou 510070,China;Guangdong Provincial Key Laboratory of Earthquake Early Warning and Safety Diagnosis of Major Projects,Guangdong Earthquake Agency,Guangzhou 510070,China;Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Key Laboratory of Earthquake Source Physics,China Earthquake Administration,Beijing 100081,China)

机构地区：[1]广东省地震局,中国地震局地震监测与减灾技术重点实验室,广州510070 [2]广东省地震局,广东省地震预警与重大工程安全诊断重点实验室,广州510070 [3]中国地震局地球物理研究所,北京100081 [4]中国地震局,震源物理重点实验室,北京100081

出　　处：《地球物理学报》2023年第11期4582-4596,共15页Chinese Journal of Geophysics

基　　金：国家自然科学基金(42104045);中国地震局地球物理研究所基本科研业务费专项(DQJB22R31);国家自然科学基金(41790463)联合资助。

摘　　要：城市下方的三维速度结构是服务城市建设规划和地震灾害风险评估等的重要资料.2020年开展的粤港澳大湾区浅层结构探测实验布设了由6172个短周期台站组成的密集台阵,并利用新型甲烷绿色震源开展了63次主动源激发.本文拾取了63次甲烷震源激发在各台站记录到的16885条初至P波,采用simul2000走时反演程序首次获取了粤港澳大湾区中心城区高分辨率的地壳浅部(1.5 km深度以上)三维P波速度结构.结果表明:(1)成像结果与区域地形和浅部岩性分布有很好的相关性.断陷区呈现低V_(P),而断隆区为高V_(P)分布,分别与碎屑沉积岩、花岗岩及变质岩等相对应.(2)广从断裂、瘦狗岭断裂、珠江口断裂和白坭—沙湾断裂两侧速度均具有明显差异.其中瘦狗岭断裂的控制作用最强,使得不同深度速度分布在南北向的差异最为显著.(3)跨断层速度剖面分布特征显示区域断裂控制着沉积层的展布和基底埋藏深度.本文研究表明,将新型绿色震源和密集台阵相结合是探测城市承载体下方速度结构和断层系统的有效方法,具备较强推广价值.The three-dimensional(3D)velocity structure beneath urban areas is an important data for urban construction planning and earthquake hazard risk assessment.The shallow structure detection experiment in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA)in 2020 deployed a dense array consisting of 6,172 short-period stations,and carried out 63 active source excitations using new methane green sources.Using the manually picked 16,885 first-arrival phases from 63-shots methane sources,we present the first high-resolution 3D shallow P-wave velocity structure(above 1.5 km depth)in the central area of the GBA.The obtained results show that(1)the velocity images have a good correspondence with the regional topography and shallow lithology distribution.The depression area presents a low V_(P) distribution,while the uplift area with high V_(P) anomalies,which corresponds to clastic sedimentary rocks,granites,and metamorphic rocks,respectively.(2)The velocities have a strong anomaly on both sides of the Guangcong fault,Shougouling fault,Zhujiangkou fault,and Baini-Shawan fault.Among them,the Shougouling fault has the strongest controlling effect,making the velocity images show obvious differences between the north and south side along the fault at different depths.(3)The cross-fault velocity profiles show that regional faults control the distribution and burial depth of sedimentary layers.Our study shows that combination using of new green methane source and dense short-period array is an effective method to detect the shallow velocity structure and fault system under urban agglomerations.

关 键 词：粤港澳大湾区 甲烷震源 密集台阵 体波层析成像 浅层速度结构 

分 类 号：P315[天文地球—地震学]