Seismic hazard assessment for Guinea, West Africa.

ABSTRACT

Guinea is located on a stable continental region in West Africa, this is a region characterised by infrequent seismic events. In this study, the seismic hazard level of Guinea and 10 main cities was determined by a probabilistic approach. The calculation was carried out for 10%, 2% and 0.5% probability of exceedance in 50 years (corresponding to 475, 2475 and 9975 years return periods, respectively). We developed a homogenized 100-year catalogue compiled from different seismic sources. Two ground motion prediction equations, originally developed for Eastern and Central North America, a stable continental region, were used for the hazard calculation. A uniform b-value of 0.70 ± 0.12, and individual activity rate (λ) were calculated for the three seismic zones considered in this study. The estimated seismic hazard was high in the Palaeozoic area of Guinea. The PGA values estimated for the study region, considering hard rock conditions, were 0.08 g, 0.27 g, and 0.57 g for 475, 2475 and 9975 years return periods, respectively. The results of this study an inform future programmes in disaster risk management and planning for new regional infrastructure.