Regionalization of global subduction ground‐motion model for application in Central America and Mexico

We extend data resources originally developed for Central America and Mexico in the Next‐Generation Attenuation (NGA)‐Subduction (NGA‐Sub) project database and use the data to customize a global ground‐motion model (GMM) for regional application. The GMM applies for peak ground acceleration, peak ground velocity, and 5%‐damped pseudo‐spectral accelerations for periods from 0.01 to 10 s, for the median orientation‐independent horizontal component of ground motion. The database for Mexico is extended by considering small magnitude ( M < 6) events and three large events ( M 7.2– M 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. These changes increase the size of the database from 593 recordings from 66 events (NGA‐Sub) to 1882 recordings from 121 events. The expanded data are examined relative to a global NGA‐Sub GMM, which reveals a number of interesting features including faster anelastic attenuation in backarc than forearc regions and generally similar levels of site response to those in the global GMM. These features are incorporated into the regionally customized model. Advantages of this GMM relative to previous regional models applied at national scale for engineering applications are that its functional form has a physical basis, and its coefficients are well constrained from global data and are only adjusted for the target region as required by regional data.