Developing a map of geologically defined site-condition categories for California
Developing a map of geologically defined site-condition categories for California
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DOI：
10.1785/0120050179
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发表时间：
2006-08-01
影响因子：
3
通讯作者：
Clahan, K. B.
中科院分区：
文献类型：
--
作者：
Wills, C. J.;Clahan, K. B.
考虑场地条件是分析和预测地震地震动的重要步骤。人们早就认识到土壤条件对放大的重要性，但是，尽管许多地震仪器站点的特征都是由其地质条件决定的，但还没有一个统一的、简单的分类适用于所有站点。由于按横波速度对台站进行分类已变得越来越普遍，因此显然需要回过头来为所有台站提供一个简单统一的分类。在太平洋地震工程研究中心的下一代衰减方程项目中，衰减方程的开发人员认识到需要考虑现场条件，并要求加州地质调查局为所有记录加州地震地面运动的台站提供现场条件信息。为了提供这些估计，我们按地质单位对可用的横波速度数据进行了分类，对地质单位进行了概括，并制作了一张地图，以便我们可以利用地图单位的范围将速度特征从测量地点转移到相同或类似材料上的地点。这张新地图不同于加州地质调查局的“加州初步现场情况地图”，因为它使用了19个地质定义的类别，而不是国家地震灾害减少计划的类别。虽然这张地图还没有覆盖整个加州，但一旦完成，它可能会为更精确地考虑地面运动计算中的场地条件提供基础。
Consideration of site conditions is a vital step in analyzing and predicting earthquake ground motion. The importance of amplification by soil conditions has long been recognized, but though many seismic-instrument sites have been characterized by their geologic conditions, there has been no consistent, simple classification applied to all sites. As classification of sites by shear-wave velocity has become more common, the need to go back and provide a simple uniform classification for all stations has become apparent. Within the Pacific Earthquake Engineering Research Center's Next Generation Attenuation equation project, developers of attenuation equations recognized the need to consider site conditions and asked that the California Geological Survey provide site conditions information for all stations that have recorded earthquake ground motion in California. To provide these estimates, we sorted the available shear-wave velocity data by geologic unit, generalized the geologic units, and prepared a map so that we could use the extent of the map units to transfer the velocity characteristics from the sites where they were measured to sites on the same or similar materials. This new map is different from the California Geological Survey "preliminary site-conditions map of California" in that 19 geologically defined categories are used, rather than National Earthquake Hazards Reduction Program categories. Although this map does not yet cover all of California, when completed it may provide a basis for more precise consideration of site conditions in ground-motion calculations.