Geospatial Variable Based Site Terms for Nonergodic Ground Motion Models
Description:
This work presents a non-ergodic site response model for California for use with the Boore, Stewart, Seyhan, and Atkinson (2014) (BSSA14) ground motion model (GMM), using geospatial variables. Geospatial variables such as elevation, water table depth, soil thickness, and distance to the coast have been found to capture the spatial pattern of geologic deposits (Wald and Allen, 2007; Zhu et al., 2015), and have been used to develop geospatial liquefaction models (Zhu et al., 2015; 2017). At the same time, ground motion databases have grown in recent years, making it possible to better capture the complexity of site effects spatially, and as a result, quantify the repeatable effects that local surface geology has on ground motion intensity. This project uses the DesignSafe Ground Motion database (Ji et al., 2022) for the state of California, containing over 57,000 ground motion recordings paired with geospatial variables as additional site terms beyond Z1.0 and VS30 (e.g. elevation, depth to water, soil thickness, surficial geology). Ground motion residuals are calculated for the database between the observed peak ground accelerations (PGA) and the BSSA14 predicted PGAs, which uses VS30 as the primary site response parameter. Mixed effects regression is performed on the residuals using geospatial explanatory variables to partition the residual, in order to produce updated site terms that account for the corresponding influence of the geospatial variables. The developed non-ergodic geospatial site terms result in a reduction in inter-site residual variability for PGA values, when compared to the conventional VS30 based site terms. The development of a non-ergodic site term for use in California using geospatial variables highlights the predictive power of geospatial data and accounts for its impact on ground motion intensity.
Session: From Earthquake Recordings to Empirical Ground-Motion Modelling [Poster Session]
Type: Poster
Date: 5/2/2024
Presentation Time: 08:00 AM (local time)
Presenting Author: Maggie
Student Presenter: Yes
Invited Presentation:
Authors
Maggie Roberts Presenting Author Corresponding Author maggie.roberts@tufts.edu Tufts University |
Laurie Gaskins Baise laurie.baise@tufts.edu Tufts University |
James Kaklamanos kaklamanosj@merrimack.edu Merrimack College |
Weiwei Zhan Weiwei.Zhan@ucf.edu University of Central Florida |
Shiying Nie shiying.nie@tufts.edu Tufts University |
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Geospatial Variable Based Site Terms for Nonergodic Ground Motion Models
Category
From Earthquake Recordings to Empirical Ground-Motion Modelling