- © 2009 Geological Society of South Africa
A probabilistic approach was used to map the seismic hazard in Democratic Republic of Congo and surrounding areas, and assess the seismic hazard level for 14 cities in the region. Seismic hazard maps for 2%, 5% and 10% chance of exceeding the indicated ground accelerations in 50 years were prepared using a homogenised 90-year catalogue compiled for moment magnitudes; the attenuation relations of Mavonga (for the Western Rift Valley of Africa), Jonathan (for eastern and southern Africa) and Atkinson and Boore (for eastern North America); 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 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 interest) is less than 10% in 50 years.