川藏铁路通麦‒鲁朗段浅层结构背景噪声成像  

Shallow Layer Tomography Study on Tongmai⁃Lulang Section of Sichuan⁃Tibet Railway

作　　者：花茜 裴顺平[1,2,3] 郭震 蔡福龙 丁林[1,2,3] 薛晓添 李磊[1,3] 李佳蔚 刘翰林 刘巍 Hua Qian;Pei Shunping;Guo Zhen;Cai Fulong;Ding Lin;Xue Xiaotian;Li Lei;Li Jiawei;Liu Hanlin;Liu Wei(Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China;State Key Laboratory of Tibetan Plateau Earth System,Resources and Environment(TPESRE),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China;University of Chinese Academy of Sciences,Beijing 100049,China;Shaanxi Earthquake Agency,Xi’an 710068,China;Department of Ocean Science and Engineering,Southern University of Science and Technology,Shenzhen 518055,China)

机构地区：[1]中国科学院青藏高原研究所,北京100101 [2]中国科学院青藏高原研究所,青藏高原地球系统与资源环境国家重点实验室,北京100101 [3]中国科学院大学,北京100049 [4]陕西省地震局,陕西西安710068 [5]南方科技大学海洋科学与工程系,广东深圳518055

出　　处：《地球科学》2022年第9期3447-3462,共16页Earth Science

基　　金：第二次青藏高原综合科学考察研究项目(No.2019QZKK0708);国家自然科学基金项目(Nos.41941016,U2039203,42130306).

摘　　要：为探明川藏铁路通麦‒鲁朗段浅层地质结构特征,有效评估铁路沿线地质灾害风险,保障铁路设施安全运转,基于短周期密集台阵波形数据利用背景噪声层析成像技术获得了浅地表高分辨率的S波精细速度结构,并结合地质调查结果,精确判断沿线断层几何形态及活动特征.S波速度结构和地质调查结果显示沿线低速区和断层分布有很好的对应关系,断裂F1~F6较好地控制了下方低速区的几何形态.结合地质及地震资料可推断:(1)米林Ms6.9地震发震构造可能属于一条由一系列叠瓦状和背冲式断裂组成的断裂体系,该断裂体系的地震活动存在不断向北西端发育的趋势,地震危险性较高.在断裂体系北西端的拉月隧道,未来可能有较强的地震活动性.(2)嘉黎断裂南支西兴拉断裂在剖面处属于隐伏断裂,F5和F6可能都属于贡日嘎布曲分支,呈高角度W倾,强烈的壳内破碎带特征,可能与嘉黎断裂不断地高角度右旋逆冲剪切运动有关.(3)研究区密集的断裂控制着地下热流循环,高温流体的溶蚀作用加剧了构造作用中岩体的破碎程度,降低了岩体稳定性,易引发多种类型的地质灾害;因此,川藏铁路通麦‒鲁朗段应配备能有效应对地质灾害的监测预警系统及应急机制,保障隧道及铁路设施的正常运转.In order to explore the characteristics of shallow geological structure of Tongmai-Lulang section of Sichuan-Tibet railway,effectively assess the risk of geological disasters along the railway and ensure the safety operation of railway facilities,high resolution S-wave velocity structure of shallow crust is obtained by ambient noise tomography based on waveform data of short-period seismic dense array in this paper,combined with geological survey results,the geometric morphology and activity characteristics of faults along the section are accurately determined.S-wave velocity structure and geological survey results show that there are good correspondences between low-velocity zones and faults distributed along the section,and F1-F6 control the geometry of the low-velocity zones below.Combining with geological analysis and seismology data,we can infer that:(1)The seismogenic structure of Milin Ms6.9 earthquake may belong to a fault system composed of a series of imbricated and backthrust faults.The seismic activities of the fault system tend to the northwest end,where the seismic risk is higher.La Yue tunnel is located in the northwest of the fault system,which may have strong seismic activity in the future.(2)Xixingla fault,the southern branch of Jiali fault,is active as a concealed fault in the section.F5 and F6 may both belong to the Gongriga-Buqu branch with high-angle W-dip and strong fracture zone characteristics which may be related to the continuous high-angle righthanded thrust shear movement of Jiali fault.(3)The dense faults in the study area control the circulation of underground heat flow.The dissolution of high-temperature fluid intensifies the fragmentation degree of rock mass in the tectonic process,reduces the stability of rock mass,and easily leads to various types of geological disasters.Therefore,the Tongmai-Lulang section of Sichuan-Tibet railway should be equipped with effective monitoring and early warning system and emergency mechanism to deal with geological disasters and ensure the normal

关 键 词：川藏铁路 短周期密集台阵 背景噪声层析成像 S波速度结构 地震学 

分 类 号：P315[天文地球—地震学]