Large-magnitude crustal seismic sources in El Salvador and deterministic hazard scenarios

Abstract

During the last years, several crustal seismic sources have been proposed in El Salvador; however, the actual destructive potential of these proposals has not been revealed yet. Here we present several seismic scenarios related with the main crustal faults in the country. We have characterized the corresponding hazard scenarios in a deterministic way, estimating the peak ground accelerations (PGA) including local site effects. In addition, we present a list of 29 sources that can be considered potentially dangerous with their main features when they are available and four seismic scenarios that we consider to be more probable. We have resorted to the February 13th 2001 Mw 6.6 destructive earthquake, the only earthquake occurred in a known crustal source in El Salvador and recorded by the strong motion network, in order to test the methodological approach and the reliability of the PGA results predicted by two available Ground Motion Prediction Equations (GMPEs) including the site effect. The consistence between the values given by the models and the ones recorded during the event provides reliability to our results. This approach allowed us to conclude that faults within the volcanic arc can produce accelerations up to 1 g in the most conservator case (Mw = 7.0), while accelerations up to 0.6 g are usual results related with specific faults within the Salvadoran Volcanic Arc. Besides, the reported damage distribution of the 8th June 1917 earthquakes and its similarity with one of the proposed scenarios allowed us to infer the possible source of this event, the Guaycume Fault.