Seismotectonic analysis and definition of seismic source zones in Cameroon, Central Africa

A compilation of databases from Cameroon and neighbouring countries, including seismicity, stress tensor distribution, gravity, magnetic, topography, lithosphere structure and geological data, is used to define its seismotectonic zonation. Based on the quality and quantity of available data, a seismotectonic map was drawn up through the characterization of subunits of concentrations of earthquake foci and, large neotectonic and structural domains. To prepare this map, a homogeneous earthquake catalogue was compiled from the literature and international data centres dated from 1852 up to 2023. Another point of study was to establish links between seismicity and deformation zones. Many faults and/or structures were identified as possibly active, although some of them are not always associated with seismicity. A seismotectonic model for Cameroon was then built from a classification of faults, neotectonic and seismogenic regions. This structured and highly data-driven approach has been developed specifically for the definition of source zones where seismicity is not well known. The results of the seismotectonic analysis allowed characterizing seventeen seismotectonic source zones in Cameroon. Five source zones are defined in the Mount Cameroon region which is the greatest seismicity activity in the study area. The crustal thickness map of Cameroon revealed a thinned transitional zone interspersed between the thickened Congo Shield and thin Pan-African belt favourable for the development of megastructures such as Central Cameroon shear zone and Kribi-Campo shear zone. This region represents the second highest seismicity zone and contains five source zones.