Characterization of Seismicity and Seismic Hazard in the Coquimbo Region, Chile: A Probabilistic Study

Abstract

In order to seismically characterize Chile’s northern Coquimbo Region, data from 2003 to 2020 were considered. The region was divided into 30 zones of \(0.5^\circ\) latitude and \(0.5^\circ\) longitude and non-extensive statistical physics was used. Both, the Sotolongo–Costa–Posadas (SCP) and Mathai models were deployed to analyze the magnitude-frequency distribution. A sub-division into cells of the catalog allowed to demonstrate that systems with value of \(q \sim 1\) present exponential behavior, while it was expected to obtain \(q > 1\), by superimposing sub-systems supporting the superstatistical model. Thus, by subdividing the Coquimbo region into south and north, we found that in both zones the entropic index is greater than 1, \(q>1\), However, in the southern zone the long-range effects are greater than in the north, according to the value obtained, which means both sectors are well described under a nonextensive statistical model, be it the SCP model or the Mathai one. The entropic index is \(q>1\) and in both cases \(R^2>0.99\). As the region is considered as a whole, the nonextensive statistical distribution is the more adequate one. With respect to probabilistic seismic hazard assessment, Mathai’s model proved to have the better fit. Thus, the frequency-interevent time distribution was used for different limit magnitude values. Our analysis showed that the probability occurrence of a seismic event in the region’s north is lower than in the south considering the same period. In the north the behavior is of Poissonian type.