Shallow velocity structure of the Luoyang basin derived from dense array observations of urban ambient noise
Shallow velocity structure of the Luoyang basin derived from dense array observations of urban ambient noise
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城市环境噪声密集阵观测得出的洛阳盆地浅层速度结构
DOI：
10.29382/eqs-2018-0252-5
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
莘海亮
中科院分区：
文献类型：
--
作者：
周铭;田晓峰;王夫运;魏运浩;莘海亮
确定沉积盆地的浅层结构在评估潜在的地震危险时很重要，因为这种盆地可以显着放大地震能量。洛阳盆地位于豫西隆起带，是一个中新生代坳陷盆地。为了表征盆地的浅层结构，我们开发了一个模型的浅层高分辨率三维（3D）剪切波速度结构的盆地应用环境噪声层析成像的密集阵列部署在盆地的107便携式数字地震仪。超过1,400瑞利波频散曲线的范围内的周期为0.5 - 5秒提取。利用周期相关射线追踪直接面波层析成像方法反演地壳浅层剪切波速度的三维变化，同时反演所有面波群速度频散数据。结果表明，在研究区地壳浅部，速度分布与地表地质和地质特征相对应。洛阳盆地具有与沉积物分布相一致的低剪切波速度特征，而熊耳山隆起和松山隆起则具有较高的剪切波速度结构。研究结果提供了一个浅层高分辨率三维速度模型，可作为强地面运动模拟和潜在地震危险性评估的基础。
Determining the shallow structure of a sediment basin is important when evaluating potential seismic hazards given that such basins can significantly amplify seismic energy. The Luoyang basin is located in the western He'nan uplift and is a Meso-Cenozoic depression basin. To characterize the shallow structure of the basin, we develop a model of the shallow high-resolution three-dimensional (3D) shear-wave velocity structure of the basin by applying ambient noise tomography to a dense array of 107 portable digital seismometers deployed over the basin. More than 1,400 Rayleigh-wave dispersion curves for periods in the range 0.5–5 s are extracted. The 3D variations of shear-wave velocity in the shallow crust are inverted using a direct surface-wave tomographic method with period-dependent ray tracing, with all the surface-wave group-velocity dispersion data being inverted simultaneously. The results show that in the shallow crust of the study area, the velocity distribution corresponds to surface geology and geological features. The Luoyang basin exhibits a low shear-wave velocity feature that is consistent with the distribution of sediment in the region, while the Xiongershan and Songshan uplifts exhibit higher shear-wave velocity structures. The results provide a shallow high-resolution 3D velocity model that can be used as a basis for simulation of strong ground motion and evaluation of potential seismic hazards.