青藏高原东南缘三维地壳形变特征与地震活动  

Three-Dimensional Crustal Deformation Characteristics and Seismicity in the Southeastern Margin of Qinghai-Xizang Plateau

作　　者：郝梅煊 潘正洋 王武星[1] 刘琦[1] 赵国强[1] HAO Meixuan;PAN Zhengyang;WANG Wuxing;LIU Qi;ZHAO Guoqiang(Institute of Earthquake Forecasting,CEA,63 Fuxing Road,Beijing 100036,China)

机构地区：[1]中国地震局地震预测研究所,北京市100036

出　　处：《大地测量与地球动力学》2025年第3期244-251,共8页Journal of Geodesy and Geodynamics

基　　金：中央级公益性科研院所基本科研业务费专项(CEAIEF2024030101);中国地震局地震预测研究所基本科研业务费专项(CEAIEF20240201)。

摘　　要：联合青藏高原东南缘地区最新的水平与垂直GPS速度场,基于球面小波多尺度分析的应变求解方法,考虑区域地震矩与应变分布的权重关系,得到青藏高原东南缘三维地壳应变特征,并分析区域形变特征与地震活动的关系。结果表明:1)研究区面应变与垂直应变特征具有一致性。高面应变与低垂直应变主要集中在青藏高原腹地和金沙江北部区域,低面应变与高垂直应变主要集中在喜马拉雅东构造结与龙门山断裂。两者在空间上呈反比分布,说明GPS观测得到的水平速度与垂直速度具有耦合性,即对于该区域地壳形变与地震危险性研究,必须考虑垂向运动因素;两者在量级上也存在较好的一致性,进一步说明该区域的地壳变形可以近似认为是连续均质的弹性行为。2)应变速率类型与震源机制解具有一致性。由GPS解算得到的青藏高原东南缘应变类型可以很好地匹配该区域震源机制解。正断层震源机制主要分布在金沙江地带,逆冲断层震源机制主要分布在龙门山断裂与喜马拉雅东构造结区域,走滑断层震源机制主要集中在鲜水河-小江断裂带等走滑剪切作用显著的断裂带附近,说明由GPS观测得到的应变特征可以较好地描述该区域构造应力场特征。结合该区域应力应变空间分布特征和地震层析成像等结果,认为龙门山断裂与喜马拉雅东构造结处于挤压应变状态。We combine the latest horizontal and vertical GPS velocity fields in the southeastern margin of Qinghai-Xizang plateau,based on the strain solving method of spherical wavelet multi-scale analysis,consider the weight relationship between regional seismic moment and strain distribution,obtain the three-dimensional crustal strain characteristics of the southeastern margin of Qinghai-Xizang plateau,and analyze the relationship between regional deformation characteristics and seismicity.The results show that:1)There is a consistency between surface strain and vertical strain in the study area.The high surface strain and low vertical strain are mainly concentrated in the central Qinghai-Xizang plateau and northern Jinshajiang regions,while the low surface strain and high vertical strain are mainly concentrated in the Eastern Himalayan Syntaxis and Longmenshan regions.The spatial inverse distribution relationship between surface strain and vertical strain shows that the horizontal velocity and vertical velocity obtained by GPS observation in this region are coupled,which indicates that vertical motion is also an indispensable consideration for the study of crustal deformation and seismic risk in this region.There is a good agreement between surface strain and vertical strain in terms of magnitude,which further indicates that the crustal deformation in this region can be approximated as a continuous and homogeneous elastic behavior.2)There is a consistency between the type of strain rate and focal mechanism solution.The strain types obtained from GPS data in the southeastern margin of Qinghai-Xizang plateau can be well matched with the focal mechanism solution in this region.The source mechanism of normal fault is mainly distributed in Jinshajiang region,thrust fault is mainly concentrated in Longmenshan and Eastern Himalayan Syntaxis regions,and strike-slip fault is mainly distributed near the fault zone with significant strike-slip shear such as Xianshuihe-Xiaojiang fault,indicating that the strain characteristics obta

关 键 词：GPS速度 三维地壳形变 青藏高原东南缘 生长扩展 地震活动 

分 类 号：P315[天文地球—地震学] P228[天文地球—固体地球物理学]