Project Abstract
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Near-surface soil layers of sedimentary basins play a critical role in modifying the amplitude, frequency and duration of earthquake ground shaking. Referred to as site e ffects, these phenomena are essential elements of evaluating earthquake hazard and risk on a regional scale, through statistical models such as ground motion prediction equations, and wave propagation simulations. One of the most important impediments in integrating In this study, we develop a sediment velocity model (SVM) that translates Vs30, the only proxy available to describe the sti ness of the near surface sediments in the Los Angeles basin, into a generic velocity profile suitable for use in wave propagation-based ground motion models. We speci cally develop a Vs30-dependent shear wave velocity model (previously referred to as Geotechnical Layer or GTL), based on the statistics of nearly a thousand measured velocity pro les with Vs30 ranging from 150 m/s to 1000 m/s. We validate the model by comparing the site ampli cation factors of the measured pro les and the SVM. We lastly develop and demonstrate the implementation of a spatially correlated random realization algorithm, intended to populate the near surface of the 3D UCVM domain with our SVM. The next step of this work is to use the pro les to improve high-frequency predictions of 3D physics-based ground motion simulations; and to develop Vs30-dependent ampli cation factors for implementation in the SCEC broadband platform. |
