On using surface-source downhole-receiver logging to determine seismic slownesses
On using surface-source downhole-receiver logging to determine seismic slownesses
复制标题
利用地表源井下接收器测井确定地震慢度
DOI：
10.1016/j.soildyn.2007.03.005
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
E. Thompson
中科院分区：
文献类型：
--
作者：
D. Boore;E. Thompson
我们提出了一种利用地面震源-井下接收地震行程时间求解慢度模型的方法。该方法估计了从所有接收器深度对旅行时间进行一次反演的慢度，并考虑了层边界的折射。模型中层界面的数量和位置可以根据岩性变化或走时数据的线性趋势来选择。基于数据线性趋势的接口可以手动选择，也可以通过自动算法选择。我们用实例站点来说明该方法，这些站点的地下物质的地质描述和独立的慢度测量是可用的。在每个站点，我们给出了对数据的不同解释得出的慢度模型。这些示例经过仔细选择，以解决接口选择的可靠性和反演识别薄层、大慢度对比和慢度梯度的能力。此外，我们在地震动放大方面比较了这些模型。这些图说明了站点放大对慢度模型中不确定性的敏感性。在慢度模型中，一维位置放大对薄层不敏感；虽然慢度在较短的深度范围内是可变的，但这种可变性对频率高达5Hz的地面运动放大几乎没有影响。
We present a method to solve for slowness models from surface-source downhole-receiver seismic travel-times. The method estimates the slownesses in a single inversion of the travel-times from all receiver depths and accounts for refractions at layer boundaries. The number and location of layer interfaces in the model can be selected based on lithologic changes or linear trends in the travel-time data. The interfaces based on linear trends in the data can be picked manually or by an automated algorithm. We illustrate the method with example sites for which geologic descriptions of the subsurface materials and independent slowness measurements are available. At each site we present slowness models that result from different interpretations of the data. The examples were carefully selected to address the reliability of interface-selection and the ability of the inversion to identify thin layers, large slowness contrasts, and slowness gradients. Additionally, we compare the models in terms of ground-motion amplification. These plots illustrate the sensitivity of site amplifications to the uncertainties in the slowness model. We show that one-dimensional site amplifications are insensitive to thin layers in the slowness models; although slowness is variable over short ranges of depth, this variability has little affect on ground-motion amplification at frequencies up to 5Hz.