A new evaluation of Seismic Hazard for the Central America Region in the frame of the RESIS II Project.

Abstract

A new evaluation of seismic hazard in the Central America region has been carried out, in the frame of the cooperation project RESIS II, financed by the Norway Cooperation Agency (NORAD). Different experts in seismic hazard from Costa Rica, Guatemala, Nicaragua , El Salvador, Norway and Spain participated in the study, which was aimed at obtaining results suitable for seismic design purposes. The analysis started with an exhaustive revision of the seismic catalogues of each country from which a global catalogue for CA has been configured and homogenised at moment magnitude, Mw. Seismotectonic models proposed for the region were revised and a regional zonation was proposed, taking into account seismotectonic data, seismicity, focal mechanisms, GPS observations and other evidences useful for defining seismic sources. In parallel, attenuation models for subduction and volcanic crustal zones were revised and the more suitable models were calibrated with strong motion data. Taking the previous inputs, the seismic hazard analysis was developed in terms of peak ground acceleration, PGA and spectral accelerations SA (T) for periods of 0.1, 0.5, 1 and 2 s, through the PSHA methodology (Probabilistic Seismic Hazard Assessment). As a result, different hazard maps were obtained for the quoted parameters, together with Uniform Hazard Spectra (UHS) in the main populations of Central America. This is the first study developed at regional scale after the last earthquakes that have occurred in the region and as a result the new generation of maps will be useful in the revision of seismic codes of the area.