A New Evaluation of Seismic Hazard for the Central America Region

A new evaluation of seismic hazard in Central America has been carried out as part of the cooperation project named RESIS II under the auspices of the Norway Cooperation Agency (NORAD). Several seismic-hazard experts from Costa Rica, Guatemala, Honduras, Nicaragua, El Salvador, Panama, Norway, and Spain participated in the study, which was aimed at obtaining results suitable for seismic design purposes. The analysis started with a thorough revision of the national seismic catalogs from which a catalog for Central America has been compiled and homogenized to moment magnitude, M-w. Seismotectonic models proposed for the region were revised, and a new regional zonation was proposed, taking into account seismotectonic data, seismicity, focal mechanisms, and GPS observations. Besides, ground-motion prediction equations (GMPEs) for subduction, volcanic, and crustal zones were revised, and the most suitable ones were calibrated with Central American strong-motion data. Subsequently, a seismic-hazard analysis was developed in terms of peak ground acceleration (PGA) and spectral accelerations SA (T) for periods of 0.1, 0.2, 0.5, 1, and 2 s, by means of the probabilistic seismic-hazard assessment (PSHA) approach. As a result, different hazard maps were obtained for the quoted parameters, together with uniform hazard spectra (UHS) for six of the capital cities of Central America. Disaggregation was also carried out in these capitals for the target motion given by the PGA and SA (1 s) and obtained for return periods of 500 years and 2500 years. Therefore, the control earthquakes for motions of short and long periods were derived. This is the first study developed in Central America at a regional scale after 10 years.