Full waveform tomography to resolve desert alluvium
Full waveform tomography to resolve desert alluvium
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全波形断层扫描解析沙漠冲积层
DOI：
10.1016/j.soildyn.2017.04.018
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发表时间：
2017
影响因子：
4
通讯作者：
B. Luke
中科院分区：
文献类型：
--
作者：
K. Tran;B. Luke
本文介绍了内华达州拉斯维加斯谷西北部地震数据集全波形层析成像的横波速度分布。背景是一个深而多变的冲积层序，包括砾石、砂、粉砂和粘土，并有一些碳酸盐胶结。利用72个等间距的检波器沿着约144米长的阵列收集地震数据，每隔6米使用一个加速落锤源。该数据集使用先进的二维全波形断层扫描方法进行解释。根据多通道表面波分析（MASW）方法，使用瑞利波频散对同一数据集进行了分析，以建立单一的一维速度剖面。MASW方法的结果显示了一个温和的速度反转。波形层析成像方法能够描述沿阵列长度至25 m深度的垂直和横向速度变化。结果显示高速层和低速层对比明显。虽然两种方法的深度平均横波速度相似，但FWI显示的变化程度得到了附近钻孔标准穿透测试（SPT）冲击次数的强烈变化以及沉积物岩性的期望的支持。
This paper presents shear wave velocity distribution developed from full waveform tomography on a seismic dataset recorded in the northwest Las Vegas Valley, Nevada. The setting is a deep and variable alluvial sequence, encompassing gravel, sand, silt and clay, with some carbonate cementation. Seismic data were collected along a ~144-m long array using 72 equally spaced geophones, with an accelerated drop-weight source applied at 6-m intervals. The dataset was interpreted using an advanced 2-D full waveform tomography method. The same dataset was also analyzed using Rayleigh wave dispersion, following the multichannel analysis of surface waves (MASW) method, to develop a single, 1-D velocity profile. Results from the MASW method indicated a mild velocity inversion. The waveform tomography method was able to characterize vertical and lateral velocity variations along the array length to 25 m depth. Results showed significantly contrasting high- and low-velocity layers. While depth-averaged shear wave velocities from the two methods were similar, the degree of variability indicated using FWI is supported by strong variation in Standard Penetration Test (SPT) blow counts from a nearby drillhole and by expectations from sediment lithology.