Use of Active Fault Data versus Seismicity Data in the Evaluation of Seismic Hazard in the Granada Basin (Southern Spain).

Abstract

In this article we evaluate the seismic hazard in the Granada Basin (southern Spain), using for the first time the slip rate of known active faults. Our study, as an attempt to compute seismic hazard using active fault data in low to moderate seismicity regions, relies on a complete database of these faults containing information relevant to their seismic potential. We obtain peak ground acceleration values above 0.4g for a return period of 475 years. This result is compared with previous evaluations carried out on the basis of the historical seismicity of the area and the application of the well-known theorem of total probability. In these cases, maximum values of 0.2g are obtained. We explain the discrepancies found between the slip rate-derived and seismicity-derived estimates of seismic hazard as owing to the different strikes of the faults in relation to the directions of the main stresses affecting the Granada Basin, in the context of the Betic Cordilleras, some of them with evidence of aseismic slip.