Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 22 4th EGU Alexander von Humboldt Conference "The Andes: Challenge for Geosciences" 2009 10.5194/adgeo-22-147-2009 http://www.adv-geosci.net/22/147/2009/ http://www.adv-geosci.net/22/147/2009/adgeo-22-147-2009.html http://www.adv-geosci.net/22/147/2009/adgeo-22-147-2009.pdf 147 153 2009-12-14 Preliminary re-evaluation of probabilistic seismic hazard assessment in Chile: from Arica to Taitao Peninsula F. Leyton fleyton@utalca.cl S. Ruiz S. A. Sepúlveda Depto. Ciencias Aplicadas, Universidad de Talca, Curicó, Chile Depto. Geología, Universidad de Chile, Santiago, Chile Chile is one of the most seismically active countries in the world; indeed, having witnessed very large earthquakes associated with high horizontal peak ground accelerations, the use of probabilistic hazard assessment is an important tool in any decision-making. In the present study, we review all the available information to improve the estimation of the probabilistic seismic hazard caused by two main sources: shallow interplate, thrust earthquakes and intermediate depth, intraplate earthquakes. Using previously defined seismic zones, we compute Gutenberg-Richter laws and, along with appropriate attenuation laws, revaluate the probabilistic seismic hazard assessments in Chile. We obtain expected horizontal peak ground acceleration with a 10% of probability of being exceeded in 50 years, reaching from 0.6 g up 1.0 g in the coast and between 0.4 g and 0.6 g towards the Andes Mountains, with larger values in Northern part of the country. The present study improves our knowledge of geological hazards in Chile, enabling the mitigation of important human and material losses due to large earthquakes in the future. % vor jede Referenz Algermissen, S. T. and D. M. 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