Ground motion prediction model for southeastern México removing site effects using the Earthquake horizontal-to-vertical ratio (EHVSR)

Abstract

We propose a ground motion attenuation model (ground motion prediction equation, GMPE) for Southeast Mexico. We suppress site effects obtained from Earthquake Horizontal to Vertical Spectral Ratio (EHVSR) as a reliable estimate of site effects. (The attenuation model was built as a function of magnitude and hypocentral distance)). We used 86 seismic events with 5.0 ? Mw ? 8.2 (earthquake recordings for the 9/7/2017, Mw8.2 Tehuantepec earthquake are included), and distances between 52 ? R ? 618 km. They were recorded in nine stations of the Engineering Institute of the National Autonomous University of Mexico (II-UNAM) accelerometric network installed in the states of Chiapas, Oaxaca, Tabasco and Veracruz. Site effects at each of these stations were estimated by using the average EHVSR. Then, by means of this spectral ratio the site effects were suppressed at each station and for every record. This work points out the need to remove the site effect in the GMPE. The current models overestimate this effect.