Re-evaluation of probabilistic seismic hazard in central Chile.

Abstract

Chile is one of the most seismically active countries in the world, having witnessed several large earthquakes that produced human and material losses; seismic hazard estimation is one of the most used tools to prevent such losses. The present study reviews the state-of-the-art of the probabilistic seismíc hazard, comparing 3 different approaches and adapting them to central Chile. We include a series ofnew findings, such as the definition ofthe main seismogenic sources (interplate, interrnediate-depth intraplate, and crustal earthquakes ), new estimations of Gutenberg-Richter laws, and the use of specific attenuation laws for each one of them. Considering this information, we compute maps showing the expected peak ground horizontal acceleration (PGA), given a certain probabi1ity and time period where is observed not only the influence of interplate earthquakes, but also the effect of intermediate-depth intraplate and crustal earthquakes. For the Santiago Metropolitan area we obtain values for PGA of 55% g for a retum period of 475 years and 72% g for a retum period of 1950 years; only 13% lower than those observed on the coast (63% g and 83% g, respectively).