Correlations for spectral accelerations in the Chilean Subduction Zone

Abstract

The correlation between pseudo-accelerations at different structural periods is an essential component in the construction of conditional mean spectra (CMS), the computation of vector-valued seismic hazard (V-PSHA), and the assessment of seismic risk of spatially distributed systems, among other applications. Spectral correlation values are highly dependent on the earthquake data set used, and thus, region-specific correlation models have been developed mainly for earthquakes in western US, Europe-Middle East, and Japan. Correlation models based on global data sets for crustal and subduction zones have also become available, but there is no consensus about their applicability on a specific region. This study proposes a new correlation model for 5% damped pseudo-accelerations in the Chilean subduction zone, using a high quality seismic catalog of 1037 ground motions from 97 interface earthquakes, recorded in Chile since 1985 to 2017. The influence of modeling assumptions and different earthquake parameters, such as magnitude and mechanism, are discussed. Finally, the study provides two illustrative applications of the correlation model: (i) computation of CMS for Santiago, (ii) and the generation of conditioned ground shaking maps.