Analytical Study of Seismic Hazard Assessment and Ground Motion Prediction for the Mambilla Plateau Region

The Mambilla Plateau in Taraba State, North East Nigeria, is a tectonically active region with documented historical seismicity associated with the Cameroon Volcanic Line and cross-cutting fault systems, yet quantitative seismic hazard assessments specific to the region remain scarce. This study conducts an analytical seismic hazard assessment for the Mambilla Plateau and surrounding areas using probabilistic seismic hazard analysis methodology. A catalog of 87 earthquakes within a 300 km radius of the study area was compiled from the International Seismological Centre global database and the Nigerian Geological Survey Agency archives, spanning the period 1960 to 2023. Gutenberg-Richter recurrence parameters were derived by maximum likelihood estimation after correcting for magnitude completeness thresholds determined by the Stepp method. Fourteen regional fault sources were mapped using topographic lineament analysis of Shuttle Radar Topography Mission data and published geological maps. Ground motion prediction equations calibrated for West African intraplate tectonic settings were selected through a residual analysis against regional recordings. Peak ground acceleration and spectral acceleration hazard curves were computed at return periods of 475 years and 2475 years at 30 arc-second grid nodes covering the study area. Results indicate peak ground acceleration values at 475-year return period ranging from 0.04 g in the plateau lowlands to 0.18 g near identified fault traces. These findings represent the first peer-reviewed probabilistic seismic hazard model for the Mambilla region and have direct implications for seismic design coefficients in building codes for Taraba State. Keywords: seismic hazard, probabilistic assessment, Mambilla Plateau, ground motion, Taraba State