Ground-motion model for subduction earthquakes in northern South America

Abstract

Subduction ground motions in northern South America are about a factor of 2 smaller than the ground motions for similar events in other regions. Nevertheless, historical and recent large-interface and intermediate-depth slab earthquakes of moment magnitudes Mw = 7.8 (Ecuador, 2016) and 7.2 (Colombia, 2012) evidenced the vast potential damage that vulnerable populations close to earthquake epicenters could experience. This article proposes a new empirical ground-motion prediction model for subduction events in northern South America, a regionalization of the global AG2020 ground-motion prediction equations. An updated ground-motion database curated by the Colombian Geological Survey is employed. It comprises recordings from earthquakes associated with the subduction of the Nazca plate gathered by the National Strong Motion Network in Colombia and by the Institute of Geophysics at Escuela Politécnica Nacional in Ecuador. The regional terms of our model are estimated with 539 records from 60 subduction events in Colombia and Ecuador with epicenters in the range of −0.6° to 7.6°N and 75.5° to 79.6°W, with Mw≥4.5, hypocentral depth range of 4 ≤ Zhypo ≤ 210 km, for distances up to 350 km. The model includes forearc and backarc terms to account for larger attenuation at backarc sites for slab events and site categorization based on natural period. The proposed model corrects the median AG2020 global model to better account for the larger attenuation of local ground motions and includes a partially non-ergodic variance model.

Semiempirical model for the estimation of site amplification in Northern South America

“…The statistical module statsmodule (Seabold and Perktold, 2010) from Python was used to perform the regressions. The details of the implementation of the algorithm for the estimation of the period-dependent coefficients are given by Arteta et al (2021). The regression analysis for the site term and the rest of the coefficients of the GMM was performed based on records contained in the previously described database (section ''Database description'').…”

“…The site amplification model proposed in this study was used in the development of a GMM for Colombia by Arteta et al (2021). The functional form of the GMM accounts for source, path, and site effects and is given by:…”

“…This article presents the development of the site response term, F S . Arteta et al (2021) give details on the development of the other terms in the GMM.…”

“…This article proposes the use of the horizontal-to-vertical ratio of the earthquake response spectra for the estimation of site response for sites in northern South America. This study is framed within current efforts led by the Colombian Geological Survey (SGC) aimed toward the development of improved GMMs that will allow for an updated evaluation of the seismic hazard in northern South America based on spectral accelerations for rock conditions (Arteta et al, 2021(Arteta et al, , 2023. These efforts are limited by the fact that there are currently no V S30 measurements nor is there an adequate geotechnical characterization for most seismic stations in Colombia.…”

Resilience of a telecommunications network subjected to correlated geographical failures

“…I know use the following equation of ground motion from Carlos Arteta et al in [8], where SA ij is the spectral acceleration at a given period; f (M i , r ij , θ) is the attenuation equation as a function of magnitude M , distance r and the model parameter vector Θ; ϵ ij is the error term for log j of event i and η i is the random effect for event i.…”