Empirical Site Response of Mexico City Developed From Regional Customization of Global Subduction Ground Motion Models
Description:
We assemble a dataset of earthquake ground motions and site parameters from Mexico that extends data resources originally developed for Central America and Mexico for the NGA-Subduction (NGA-Sub) project database. We have used the data to provide regional customization of NGA-Sub global Ground Motion Models (GMMs) for application in Mexico, with a special focus on the site response of Mexico City (CDMX). The database for Mexico is extended by considering small magnitude (Mw < 6) events and three large events (Mw 7.2-8.3) in 2017 and 2018. The latter are particularly important, because they are well recorded over a broad distance range and apply for hazard-critical conditions. Here, we focus on presenting the site response observed in CDMX, which is modelled as a function of time-averaged shear wave velocity in the upper 30 m of the site (VS30) and the intensity of shaking for reference site conditions (Peak Ground Acceleration at a Rock site, PGAr).
The proposed empirical model has several important differences from prior work. First, it is properly centered with respect to GMMs. Second, it is referenced to VS30=760 m/s, which is much firmer than prior practice in which the reference site was taken from a location on the UNAM campus with VS30 ~300 m/s; this has the effect of increasing site response estimates. Third, site amplification is found to be nonlinear, whereas prior models have assumed linear response. The level of nonlinearity is characterized utilizing a seismic zonation that has been previously used for CDMX, being more pronounced for softer sites (e.g., Zone III) than stiffer sites (Zone I). The nonlinear effect is pronounced at short periods and disappears at long periods, as expected. Benefits of the provided model are that a common framework is used within and outside the Valley of Mexico (unlike current practice) and the model combines the applicable features of global models while providing appropriate regional and subregional customization.
Session: From Sensors and Networks to Site Characterization and Site Response: Coming Full Circle
Type: Oral
Date: 4/18/2023
Presentation Time: 10:30 AM (local time)
Presenting Author: Victor Contreras
Student Presenter: No
Invited Presentation:
Authors
Victor Contreras Presenting Author Corresponding Author victor.contreras@udp.cl Universidad Diego Portales |
Jonathan Stewart jstewart@seas.ucla.edu University of California, Los Angeles |
Xyoli Pérez-Campos xyoli@igeofisica.unam.mx Universidad Nacional Autónoma de México |
Juan Mayoral JMayoralV@iingen.unam.mx Universidad Nacional Autónoma de México |
Daniel De La Rosa DdelaRosaA@iingen.unam.mx Universidad Nacional Autónoma de México |
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Empirical Site Response of Mexico City Developed From Regional Customization of Global Subduction Ground Motion Models
Category
From Sensors and Networks to Site Characterization and Site Response: Coming Full Circle