Horizontal and Vertical Ground-Motion Duration Prediction Models from Interplate and Intermediate-Depth Intraslab Earthquakes in Mexico City

ABSTRACT In this study, we present predictive models for significant ground-motion duration from interplate and intermediate-depth intraslab earthquakes at Mexico City for the horizontal components, the vertical component, and the vertical-to-horizontal ratio case. The considered sites are located over several zones in Mexico City, from rock to soft-soil sites. For the ground-motion duration models, the significant durations for ranges between 5% and 75%, 5% and 95%, and 2.5% and 97.5% of Arias intensity are considered for the analyses. The equations were developed as functions of magnitude, distance of the earthquake, and site period using 16 and 23 event recordings from interplate and intermediate-depth intraslab earthquakes at the hill, transition, and lakebed zones of the city using mixed-effect regression analyses. For the intraslab events, in particular, the new database includes recordings from two significant normal-faulting events that occurred in 2017. The models lead to differences with respect to the previous models. Therefore, predictive models for both considered focal mechanisms are proposed. The model is valid for interplate events at distances from 280 to 500 km and magnitude Mw from 6 to 8.1, for intraslab events at distances of 100 km up to about 650 km, magnitude Mw from 5 to 8.2, and focal depths from 40 km to over 120 km.