Preliminary Seismic Hazard and Risk Assessment for the Continent of South America

Abstract eng:
In this paper, we present a sensitivity study of seismic hazard and risk for the Continent of South America by considering inputs from three hazard models: The 2016 United States Geological Survey (USGS) Sensitivity model for South America, the 2015 Global Earthquake Model (GEM) model for South America, and the 2015 Medina et al. model for Chile. The 2016 USGS Sensitivity model builds on the 2010 USGS model for South America that incorporated an earthquake catalog from 1900 through 2008, a fault database including about 100 crustal faults, a subduction-interface model based on observed seismicity rates, and ground motion models applied in the 2008 conterminous United States (U.S.) National Seismic Hazard Model (NSHM). In this paper, we develop the 2016 USGS Sensitivity model by updating the 2010 USGS model with a new earthquake catalog through 2013 and several new ground motion models. However, we apply the same fault parameters for subduction and crustal tectonics that were applied in the 2010 USGS model for South America so it is not an independent model and is only considered as a sensitivity study. The 2015 GEM model considers additional information for several countries on earthquake locations, faults, and ground shaking. The 2015 Medina et al. model for Chile incorporates new subduction-interface and crustal rupture models based on information obtained from experts in Chile. All three models incorporate subduction zone geometry that is based on non-planar representations of the three-dimensional geometry of subducting slabs as defined in the USGS Slab 1.0 model. Comparison of the three models is useful for understanding uncertainties in the modeling process. We find significant differences greater than 0.1 g and up to 50% in several places across South America, with respect to the 2010 USGS model, which suggests that additional seismic hazard research is necessary. To understand the impact of these types of hazard maps, we use the 2010 USGS South America hazard map (the 2016 sensitivity study model was not available for this analysis) to integrate that with population data and assess the number of people that are exposed to higher ground shaking levels.

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