新疆地区地壳S波速度结构及径向各向异性研究  

Crustal S-wave Velocity Structure and Radial Anisotropy in Xinjiang Region

作　　者：周铭[1,2] 李红谊[1,3] 李信富[1,3] 谭静[3] 孙三健[3] 欧阳龙斌 郑丹[3] 

机构地区：[1]“地下信息探测技术与仪器”教育部重点实验室(中国地质大学,北京),北京100083 [2]中国地震局地球物理勘探中心,河南郑州450002 [3]中国地质大学(北京)地球物理与信息技术学院,北京100083

出　　处：《地震工程学报》2014年第4期1047-1058,共12页China Earthquake Engineering Journal

基　　金：国家自然科学基金项目(40804007,41174050);中央高校基本科研业务费专项资金

摘　　要：应用背景噪声层析成像方法对新疆地区地壳S波速度结构以及径向各向异性进行了研究。利用中国地震局数字地震台网和吉尔吉斯斯坦及哈萨克斯坦台网记录的2009年1月至9月的连续三分量背景噪声数据,对所有台站对之间进行互相关计算,通过时频分析和相位匹配技术得到了每个台站对8s到50s的群速度和相速度频散曲线,显示出明显的横向不均匀性,与研究区主要地质结构和构造单元具有良好的相关性。通过反演纯路径频散数据得到了地壳和上地幔顶部的S波速度结构和径向各向异性的结果;根据SH波和SV波速度结构差异得到研究区内的径向各向异性的分布特征;讨论了各向异性产生的机理。Northwest China is an ideal site for studying the effects of mountain-basin coupling due to its complex topography and tectonic structure.In this study,we construct crustal shear wave velocity structure and radial anisotropy in the crust and uppermost mantle in the Xinjiang region by ambient noise seismic tomography.The data include 9months（2009January to 2009September）of three-component continuous data recorded at 74 seismic stations of the China Provincial Digital Seismic Networks and regional Kyrgyzstan and Kazakhstan Networks.Empirical Rayleigh and Love wave Green＇s functions are obtained from interstation cross-correlations.Group velocity and phase velocity dispersion curves between 8sand50 speriods are measured for each interstation path by applying the time-frequency analysis method with phase-matched processing.The group velocity and phase velocity maps show clear lateral variations that correlate well with major geological structures and tectonic units in the study regions.At short periods（20s）,the basins show low group velocity and phase velocity,and the eastern part of Tarim Basin displays relatively lower velocities than the western part.A small patch of high velocity is observed in the northwest part of Tarim Basin,indicating that the structure beneath Tarim Basin is not horizontally homogeneous.The orogenic belt shows high velocity.As the period increases,the imprint of the sedimentary layers diminish.At long periods（30s）,surface wave velocities are strongly influenced by crust thickness and shear velocities in the lower crust and uppermost mantle.High velocity is observed beneath the basins.In contrast,the Tianshan orogenic belt stands out as a low-velocity region.SV and SH wave velocity structures of the crust and upper mantle are inverted from Rayleigh and Love wave dispersion maps.Because of thick sedimentation in the basins,S-wave velocities of the Tarim and Junggar basins are relatively low at shallow depth,whereas S-wave velocities of the mountain area are high due to the widely

关 键 词：新疆地区 塔里木盆地 背景噪声层析成像 群速度 相速度 径向各向异性 

分 类 号：P315.31[天文地球—地震学]