刘冠男^1,2,,
柳存喜³,
王志^4,5,,
1. 地球探测与信息技术教育部重点实验室(成都理工大学), 成都理工大学地球物理学院, 成都 610059
2. 数学地质四川省重点实验室(成都理工大学), 成都 610059
3. 雅砻江流域水电开发有限公司, 成都 610051
4. 中国科学院南海海洋研究所, 边缘海与大洋地质重点实验室, 广州 510301
5. 南方海洋科学与工程广东省实验室(广州), 广州 511458

基金项目: 国家自然科学基金面上项目（42074047），国家自然科学基金重大研究计划（91955204，92058210），第二批青藏高原科学考察研究计划（2019QZKK2704）和数学地质四川省重点实验室开放基金（scsxdz2020yb03）联合资助


详细信息

作者简介: 刘冠男, 地球物理学专业在读博士研究生, 主要从事青藏高原及其周缘的地震层析成像研究.E-mail: liuguannan@stu.cdut.edu.cn

通讯作者: 王志, 博士, 教授, 从事地球物理及大陆动力学方面的研究.E-mail: zhiwang@scsio.ac.cn

中图分类号: P315;P541

收稿日期:2021-01-25
修回日期:2021-05-18
上线日期:2021-11-10

The response of moderate-large earthquake initiations to multi-parameter variations of deep structures in southeastern Tibetan plateau

LIU GuanNan^1,2,,
LIU CunXi³,
WANG Zhi^4,5,,
1. Key Laboratory of Earth Exploration and Information Technology of Ministry of Education(Chengdu University of Technology), College of Geophysics, Chengdu University of Technology, Chengdu 610059, China
2. Geomathematics Key Laboratory of Sichuan Province(Chengdu University of Technology), Chengdu 610059, China
3. Yalong River Hydropower Development Company Ltd., Chengdu 610051, China
4. Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China
5. Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou 511458, China


More Information

Corresponding author: WANG Zhi,E-mail:zhiwang@scsio.ac.cn

MSC: P315;P541

--> Received Date: 25 January 2021
Revised Date: 18 May 2021
Available Online: 10 November 2021


摘要
摘要:本研究通过反演294，777高质量纵-横波震相走时数据对，获得了青藏高原东南缘地壳及上地幔的高分辨率P波、S波速度和泊松比多参数三维结构图像，同时结合多参数的梯度场，分析了深部多参数属性变化与近50年来强震（震级≥ 5.0，M5+）孕育之间的响应关系.研究表明：（1）青藏高原东南缘多参数结构呈现出明显的横向不均性，松潘-甘孜块体的中下地壳为低速和高泊松比异常，反映了具有塑性特征的物质存在，该属性特征对强震的触发具有较显著的影响；（2）通过对过去50年内发生在青藏高原东南缘的强震（M5+）空间分布特征研究发现，绝大多数强震发生在地震层析成像边界带（Tomographic Edge Zone，TEZ）.本研究结果表明，63.3%~78.4%的强震事件发生在P波速度和泊松比TEZ上，而8.4%~20.1%和11.7%~16.7%的强震事件分别发生在参数高异常带（High-Value Zone，HVZ）和参数低异常带（Low-Value Zone，LVZ）上.S波速度参数的TEZ孕震构造特征比例与P波相比有一定的下降（45.7%~46.3%），相应的HVZ和LVZ孕震构造特征比例稍有上升趋势（36.4%~36.7%、17.3%~17.6%）.以上两个特征表明，在青藏高原东南缘，强震触发的主要控制因素可能是块体间的强烈的相互作用，同时，孕震区流体侵入在地震诱发中扮演了重要的角色.根据本次及作者前期的研究认为，青藏高原东南缘区域内绝大多数强震事件与TEZ之间的正相关的响应关系并不是一个偶然现象，可能是地震孕育和地壳构造之间存在的某种关联性.本研究所揭示的地震孕育特征为青藏高原东南缘乃至整个青藏高原的中长期防灾减灾以及重大工程建设等提供了重要的参考信息.
关键词: 青藏高原东南缘/
多参数属性变化/
层析成像边界带/
强震触发

Abstract:In this study, high-resolution three-dimensional (3-D) seismic models of multiple parameters in the crust and uppermost mantle were determined in Southeastern (SE) Tibetan plateau by inverting 294, 777 P- and S-wave pairs of high-quality travel times. To reveal the detailed variations of these seismic structures, the gradient values were also calculated from the obtained multi-parameter models. We then investigated the correlations of the variations of multiple parameters and spatial distributions of large historic earthquakes (magnitude equal to or greater than 5.0, M5+) occurred in the past 50 years. The present study indicates that: (1) widely spread existence of low-V and high-σ anomalies are observed in the lower crust and uppermost mantle, reflecting presumed ductile deformation of rheologic matters which has significantly influence on the initiations of large earthquakes in SE Tibetan plateau; (2) a dominating percentage of M5+ earthquakes occurred in the tomographic edge zone (TEZs) in the past 50 years was revealed in the SE Tibetan plateau. Our results indicate that 63.3%~78.4% earthquakes (M5+) were located in the TEZs of V_P and S models, while 8.4%~20.1% and 11.7%~16.7% earthquakes (M5+) were located in high-value zones (HVZs) and low-value zones (LVZs), respectively. Whilst, the percentage of earthquakes occurred in TEZs of V_S falls to 45.7%~46.3% and those in HVZs and LVZs increase to 36.4%~36.7% and 17.3%~17.6%, respectively. According to the above analyses, we suggest that the key factor of large earthquake generation in SE Tibetan plateau have mainly attributed to the strong interaction along the plate boundaries, and fluid processes along the TEZs might have played a crucial role in initiating the M5+ earthquakes.
Based on the present and the previous studies by the authors, we argued here that positive correlation between M5+ earthquakes and the TEZs is not unique to SE Tibetan plateau. Some of famous earthquakes in regions with different tectonic settings (e.g., Taiwan orogenic belt, forearc of the NE Japan subduction zone, etc.) are also associated with local TEZ. The present study could provide insights to long-term mitigation of regional seismic hazards in SE Tibetan plateau and probably elsewhere.
Key words:Southeastern (SE) Tibetan plateau/
Multi-parameter variations/
Tomographic edge zone (TEZ)/
Large earthquake initiations



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