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A generic soil velocity model that accounts for near-surface conditions and deeper geologic structure

October 30, 2020

Near-surface soil conditions can significantly alter the amplitude and frequency content of incoming ground motions – often with profound consequences for the built environment – and are thus important inputs to any ground-motion prediction. Previous soil-velocity models (SVM) have predicted shear-wave velocity profiles based on the time-averaged shear-wave velocity in the upper 30 m (VS30). This article presents a generic soil-velocity model that accounts both for near-surface conditions (VS30) and deeper geologic structure, as represented to the depth at which the profile reaches a velocity of 1.0 km/s (Z1.0). To demonstrate the advantages of our new SVM, we apply it to the Cascadia Region of North America, where numerous geologic basins and glaciated landscapes give rise to a wide range of VS30 and Z1.0 combinations. This soil velocity model yields good estimates of site response across all site conditions, and significantly improves upon a model calibrated using only VS30 data. In conjunction with existing models that describe the deep velocity structure of the region (e.g., (Stephenson et al., 2017) [27]; the proposed model is particularly suited for use in regional-scale predictions of site response, liquefaction, landslides, infrastructure damage, and loss. The proposed methodology is broadly applicable to the development of SVMs elsewhere, and with improved understanding of near-surface and deep velocity structures, can facilitate more accurate ground-motion predictions globally.

    Publication Year 2021
    Title A generic soil velocity model that accounts for near-surface conditions and deeper geologic structure
    DOI 10.1016/j.soildyn.2020.106461
    Authors Nasser A. Marafi, Alex R. R. Grant, Brett W. Maurer, Gunjan Rateria, Marc O Eberhard, Jeff W Berman
    Publication Type Article
    Publication Subtype Journal Article
    Series Title Soil Dynamics and Earthquake Engineering
    Index ID 70223195
    Record Source USGS Publications Warehouse
    USGS Organization Earthquake Science Center