Seismic hazard in the DRC and Western Rift Valley of Africa

Abstract

A probabilistic approach was used to assess the seismic hazard in Democratic Republic of Congo and surrounding areas. Seismic hazard maps were prepared using a 90-year catalogue compiled for homogeneous Ms magnitudes; the attenuation relations of Mavonga (for the Western Rift Valley of Africa), Atkinson and Boore (for Eastern North America) and Jonathan (for Eastern and Southern Africa); and the EZ-Frisk software package. The highest levels of seismic hazard were found in the Lake Tanganyika Rift seismic zone, where peak ground accelerations (PGA) in excess of 0.32 g, 0.22 g and 0.16 g are expected to occur with 2%, 5% and 10% chance of exceedence in 50 years, respectively. The seismic hazard in the Congo basin diminishes with distance away from the Western Rift Valley until, at a distance of about 450 km, the chance of exceeding 0.05 g (the threshold value of engineering interst) is less than 10% in 50 years.