Inslab earthquakes of Central Mexico: Peak ground-motion parameters and response spectra

Abstract

We developed equations to predict pseudoacceleration response spectra (5% damping), peak ground acceleration, and peak ground velocity at free-field rock sites for intermediate-depth, normal-faulting inslab earthquakes of Central Mexico. The data set comprises 16 earthquakes (5.2 <= M-w <= 7.4

35 <= H <= 138 km) recorded at local and regional distances (R <= 400 km). It represents a homogeneous catalog with respect to tectonic regime, fault mechanism, and soil class. Our results show larger amplitudes in the epicentral area from inslab events than from interplate events, a consequence of higher stress drops during the former type of earthquakes. Peak ground accelerations from moderate to large (M-w > 6.0) inslab events significantly exceed those from interplate events with similar magnitude, reaching almost three times for the largest events. The ground motion due to inslab events, however, decays faster than for the thrust events. Our results are in reasonable agreement with other studies based on Japanese and the worldwide data.