川滇地区壳幔方位各向异性研究  

Study on Crust-Mantle Azimuthal Anisotropy in Sichuan-Yunnan Region

作　　者：吴宇琴 吴珊珊 周思远 李凤英 赵育飞 WU Yuqin;WU Shanshan;ZHOU Siyuan;LI Fengying;ZHAO Yufei(Yunnan Earthquake Agency,2 Lan’an Road,Kunming 650000,China;Shanghai Earthquake Agency,87 Lanxi Road,Shanghai 200062,China)

机构地区：[1]云南省地震局,昆明市650000 [2]上海市地震局,上海市200062

出　　处：《大地测量与地球动力学》2023年第1期89-94,共6页Journal of Geodesy and Geodynamics

基　　金：中国地震局地震科技星火计划(XH20020Y)。

摘　　要：利用2011~2013年在川滇地区布设的190台宽频带流动地震台站,采用背景噪声程函层析成像方法和远震面波亥姆霍兹方程层析成像方法对川滇地区的地壳上地幔各向异性结构进行研究,得到高分辨率下的6~60 s瑞利面波相速度和方位各向异性结构。结果表明:1)川滇地区上地壳各向异性方向与地表构造走向一致,反映出川滇块体向东南向挤出的构造运动特征;2)川滇地区中下地壳存在较强的方位各向异性相速度低速异常,符合中下地壳流模型;3)以26°N为界,川滇地区南部地壳与上地幔的各向异性方向不一致,表明其下方可能存在壳幔解耦变形;4)川滇地区南部长周期瑞利面波的方位各向异性特征与剪切波分裂方向一致,均为近EW向,推测可能为印度板块东向俯冲回撤引起的东西向地幔流。Using 190 broadband temporary stations in the Sichuan-Yunnan region from 2011 to 2013,we analyze Rayleigh surface wave phase velocity and anisotropic structure from 6 s to 60 s of the crust and upper mantle in Sichuan-Yunnan region based on eikonal equation tomography and Helmholtz equation tomography.The results show that:1)The anisotropy direction of the upper crust is consistent with the trend of the surface structures,reflecting the tectonic movement characteristics of the southeast extrusion of the Sichuan-Yunnan block.2)There are low velocity anomalies with strong anisotropy in the middle and lower crust of Sichuan-Yunnan block,which is consistent with the middle and lower crust flow model.3)Bounded by 26°N,the anisotropy direction is different between crust and upper mantle in southern Sichuan-Yunnan,indicating that crust-mantle deformation is decoupled in this region.4)The long period surface wave anisotropy direction is nearly EW direction,which is consistent with the shear wave splitting.It may be caused by the east-subduction and retracement of the Indian plate.

关 键 词：面波 方位各向异性 程函方程 亥姆霍兹方程 

分 类 号：P313[天文地球—固体地球物理学]