利用背景噪声成像研究合肥-金华剖面地壳速度结构及径向各向异性的东西差异  

NW—SE structural contrast of shear wave velocity and radial anisotropy beneath the Hefei—Jinhua seismic profile derived from ambient noise tomography

作　　者：吴珊珊 姜明明[1,3] 何玉梅 赵亮[3,4] 艾印双[1,2,3] 

机构地区：[1]中国科学院地球与行星物理重点实验室,中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学,北京100049 [3]中国科学院青藏高原地球科学卓越创新中心,北京100101 [4]岩石圈演化国家重点实验室,中国科学院地质与地球物理研究所,北京100029

出　　处：《地球物理学报》2018年第2期584-592,共9页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41490612,41274002)资助.

摘　　要：背景噪声成像能够为地壳内部结构提供地震波速的观测证据,能够增进对地壳结构与物性的认识.本文利用背景噪声成像方法对合肥—金华流动地震台阵55个台站数据进行了分析反演,获得了华北克拉通与华南块体东部构造边界附近区域的地壳S波速度与径向各向异性结构.成像结果表明,以东经118°—118.5°附近为界,西北部表现为地壳低速异常和中下地壳正的径向各向异性,东南部表现为地壳高速异常,下部地壳存在负的径向各向异性.由此,本文推测地震波速结构差异反映了地壳内部物质与温度的差异,这种差异与两个地区自中生代晚期以来经历了截然不同的岩浆活动相关.Ambient noise tomography can image the crustal seismic velocity structure, and further provide observational evidence for better understanding the structural and physical properties within the crust. Here, we used the ambient noise tomography method to study S wave velocity and radial anisotropy beneath the eastern tectonic boundary belt between the North China Craton and South China Block with seismic data recorded by a Hefei-Jinhua portable seismic array. Our results indicate that bounded by near 118°E-118. 5°E, the northwestern part of the profile shows low velocity in the crust and positive radial anisotropy in the mid-to-lower crust, while the southeastern part exhibits relatively high velocity in the crust and negative radial anisotropy in the lower crust.Based on these tomographic results, we infer that the differences of S-wave velocity and radial anisotropy are associated with variations of crustal materials and temperature, which could be attributed to two distinct magmatic and volcanic activities experienced by the two areas since the late Mesozoic.

关 键 词：地壳S波速度 径向各向异性 背景噪声层析成像 合肥金华地震观测剖面 

分 类 号：P315[天文地球—地震学]