Empirical site classification of seismological stations in Chile using horizontal-to-vertical spectral ratios determined from recordings of large subduction-zone earthquakes

Abstract

Despite the significant upgrade and expansion of the seismic monitoring network in Chile over the past several years, precise site characterization of a large number of seismological stations is still lacking, thus hindering a robust development of tools that could improve prediction of regional seismic hazard. To enhance our understanding of site effects in Chilean seismological data, this study classifies 136 stations using the horizontal-to-vertical spectral ratio (HVSR) method based on a database of 283 triaxial ground-motion records from 22 subduction interface earthquakes with moment magnitudes ranging from 6.8 to 8.8 that occurred between 1985 and 2015. This classification, which is based on the SESAME guidelines, divides recording stations into four types according to the shape of the station-average HVSR curve (single-peak, double-peak, broad/multiple-peak, and flat). Furthermore, the variability of the mean HVSRs with different source, path and site parameters is investigated. The derived HVSR results are also compared with those presented in previous HVSR studies for Chile. Finally, representative shear-wave velocity profiles along with parametric uncertainties are estimated for stations with a single-peak HVSR curve using a Bayesian statistical inversion framework.