Empirical Evaluation of Tailings Dam Stability Under Seismic Loading Conditions at Processing Plants in North Central Nigeria

Tailings storage facilities represent one of the highest-consequence infrastructure elements at mining operations, and their stability under seismic loading has received insufficient attention in Nigeria's moderate seismicity context. This study empirically evaluates the seismic stability of tailings dams at mineral processing plants in Plateau and Nassarawa states, North Central Nigeria. Geotechnical site investigations were conducted at four tailings storage facilities, including standard penetration testing, cone penetrometer testing, and shear wave velocity measurement to characterise material properties and liquefaction potential. Seismic hazard assessment used published probabilistic seismic hazard data for the North Central region, adopting a 475-year return period acceleration as the design event. Pseudo-static and Newmark displacement analyses were performed for each facility using characterised material properties. Results reveal that two facilities contain zones of loose, saturated tailings with cyclic stress ratios below the cyclic resistance ratio, indicating liquefaction susceptibility under the design seismic event. Estimated Newmark displacements at one facility exceed 300 millimetres, suggesting potential dam crest settlement and freeboard loss sufficient to trigger overtopping failure. Liquefaction risk mitigation options including drainage enhancement and reinforcement berm construction are evaluated. The study recommends mandatory seismic stability assessment as part of periodic tailings facility reviews under the forthcoming Nigerian Dam Safety Regulations. Keywords: tailings dam, seismic stability, liquefaction, North Central Nigeria, geotechnical assessment.