The Atlantic and Gulf Coastal Plains (CPs) are characterized by widespread accumulations of low-velocity sediments and sedimentary rock that overlay high-velocity bedrock. Geology and sediment thickness greatly influence seismic wave propagation, but current regional ground motion amplification and seismic hazard models include limited characterization of these site conditions. In this study, a new regional seismic velocity model for the CPs is created by integrating shear wave velocity (VS) measurements, surface geology, and a sediment thickness model recently developed for the CPs. A reference rock VS of 3000 m/s has been assumed at the bottom of the sedimentary columns, which corresponds to the base of Cretaceous and Mesozoic sediments underlying the Atlantic CP and the Gulf CP, respectively. Measured VS profiles located throughout the CPs are sorted into five geologic groups of varying age, and median VS profiles are developed for each group by combining measured VS values within layer thicknesses defined by an assumed layering ratio. Statistical analyses are also conducted to test the appropriateness of the selected groups. A power law model with geology-informed coefficients is used to extend the median velocity models beyond the depths where measured data were available. The median VS profiles provide reasonable agreement with other generic models applicable for the region, but they also incorporate new information that enables more advanced characterizations of site response at regional scales and their effective incorporation into seismic hazard models and building codes. The proposed median velocity profiles can be assigned within a grid-based model of the CPs according to the spatial distribution of geologic units at the surface.

中文翻译：

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基于实测剪切波速度、沉积物厚度和地表地质的美国大西洋和墨西哥湾沿岸平原区域地震速度模型

大西洋和墨西哥湾沿岸平原 (CP) 的特点是低速沉积物和沉积岩广泛堆积，覆盖着高速基岩。地质和沉积物厚度极大地影响地震波传播，但当前的区域地震动放大和地震灾害模型对这些场地条件的描述有限。在这项研究中，通过积分剪切波速度（V）创建了一个新的CPs区域地震速度模型S) 测量、表面地质学以及最近为 CP 开发的沉积物厚度模型。参考岩石VS假设沉积柱底部的流速为 3000 m/s，分别对应于大西洋中部和海湾中部下方的白垩纪和中生代沉积物的底部。测量电压S位于整个 CP 的剖面被分为五个不同年龄的地质组，中值 VS通过结合测量的 V 为每个组开发配置文件S由假设的分层比率定义的层厚度内的值。还进行统计分析来测试所选组的适当性。具有地质信息系数的幂律模型用于将中值速度模型扩展到可获取测量数据的深度之外。中值VS剖面与适用于该地区的其他通用模型提供了合理的一致性，但它们也包含了新的信息，可以更先进地描述区域尺度的场地响应，并将其有效地纳入地震灾害模型和建筑规范中。所提出的中值速度剖面可以根据地表地质单元的空间分布在基于网格的 CP 模型中进行分配。