A geostatistical approach to mapping site response spectral amplifications
A geostatistical approach to mapping site response spectral amplifications
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DOI：
10.1016/j.enggeo.2010.05.010
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发表时间：
2010-08
影响因子：
7.4
通讯作者：
E. Thompson;L. Baise;R. Kayen;Yasuo Tanaka;Hajime Tanaka
中科院分区：
文献类型：
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作者：
E. Thompson;L. Baise;R. Kayen;Yasuo Tanaka;Hajime Tanaka
如果在感兴趣的地点不存在对地震性质的定量估计，则必须根据在其他地点收集的数据来估计场地反应频谱放大。目前，最常见的方法是利用场地类别与地表地质图的相关性。类似地，在地表地质未知的情况下，可以利用场地类别与地形坡度的相关性。我们的目标是确定和验证一种方法，以更高的空间分辨率和精确度来估计需要额外努力的区域的场地响应。该方法由三部分组成：特定区域的数据采集，用于内插地震属性的空间模型，以及由内插的地震属性计算频谱放大的理论方法。我们考虑了三种空间内插方案：与地表地质相关，称为地质趋势(GT)，普通克里格法(OK)，和带有趋势的克里格法(KT)。我们使用阻抗的平方根方法从地震属性中估计频谱放大，从而将频率相关的频谱放大与深度相关的地震属性联系起来。因此，这种方法适用的周期范围受到勘探深度的限制。对日本神户地区近地表S波慢度(SS)的密集调查表明，地质统计学方法比地形斜率和GT方法对SS的估计更准确，OK和KT方法的估计效果一样好。我们更喜欢KT模型，因为它可以与覆盖更大区域的地质图无缝集成。经验谱放大表明，特定区域的数据比地形斜率法更准确地估计了观测到的中值短周期放大。
If quantitative estimates of the seismic properties do not exist at a location of interest then the site response spectral amplifications must be estimated from data collected at other locations. Currently, the most common approach employs correlations of site class with maps of surficial geology. Analogously, correlations of site class with topographic slope can be employed where the surficial geology is unknown. Our goal is to identify and validate a method to estimate site response with greater spatial resolution and accuracy for regions where additional effort is warranted. This method consists of three components: region-specific data collection, a spatial model for interpolating seismic properties, and a theoretical method for computing spectral amplifications from the interpolated seismic properties. We consider three spatial interpolation schemes: correlations with surficial geology, termed the geologic trend (GT), ordinary kriging (OK), and kriging with a trend (KT). We estimate the spectral amplifications from seismic properties using the square root of impedance method, thereby linking the frequency-dependent spectral amplifications to the depth-dependent seismic properties. Thus, the range of periods for which this method is applicable is limited by the depth of exploration. A dense survey of near-surface S-wave slowness (Ss) throughout Kobe, Japan shows that the geostatistical methods give more accurate estimates of Ssthan the topographic slope and GT methods, and the OK and KT methods perform equally well. We prefer the KT model because it can be seamlessly integrated with geologic maps that cover larger regions. Empirical spectral amplifications show that the region-specific data achieve more accurate estimates of observed median short-period amplifications than the topographic slope method.