Probabilistic seismic hazard assessment for the main cities along the continental section of the Cameroon volcanic line

A probabilistic seismic hazard assessment has been carried out along the continental section of the Cameroon volcanic line (CVL) in West Africa. We compiled a catalogue of local earthquakes from different sources and homogenize the magnitudes to moment magnitude (Mw). The seismicity of the CVL is concentrated around Mount Cameroon the active volcano and diffuse on the rest. Three seismic source zones were identified: one in Mount Cameroun, the second NE of the volcano in the grabens of Kumba-Tombel, and the third seismic source corresponds to West Cameroon horst. The recurrence model is that of Gutenberg and Richter, ZMAP software was used to decluster the catalogue and to determine seismic parameters for each source zone. To calculate the hazard, we choose two ground motion prediction equations, and to account for uncertainties, a logic tree approach was implemented using CRISIS software. We estimated the peak ground acceleration (PGA) for eleven cities spread along the CVL, for return period (RP) 475 and 2475 years. The results show that for RP 475 years, Buea, located at the foot of Mount Cameroon, has a PGA of 10% g . This value decreases as one moves away from Buea. The seismic hazard was also calculated for the period of 0.2s. Uniform hazard spectra for RP 475 and 2475 years are plotted for three cities, each chosen in one of the seismic source zone. For each city and RP, the spectral acceleration increases with the period, up to around 0.1s, and then it decreases as the period increases.