Seismic Hazard Assessment for Critical Infrastructure Sites in Kano Metropolis, North West Nigeria

Kano is Nigeria's second largest metropolitan area and hosts critical infrastructure including major hospitals, the Malam Aminu Kano International Airport, and Kano Electricity Distribution facilities, none of which have undergone formal probabilistic seismic hazard assessment despite the proximity of the West African Rift System and documented historical seismicity in the region. This study conducts a probabilistic seismic hazard assessment for Kano metropolis, integrating a revised earthquake catalogue, updated seismic source characterisation, and site-specific ground motion measurements. A comprehensive earthquake catalogue was compiled from ISC, NEIC, and Nigerian Geological Survey records for the period 1900 to 2024, subjected to declustering and magnitude homogenisation. Three seismic source zones were delineated based on spatial clustering of seismicity and proximity to mapped faults in the regional geological database. Ground motion prediction equations calibrated for West African cratonic settings were selected for the hazard computation. Site-specific Vs30 values derived from HVSR measurements at 40 sites across Kano metropolis were used to perform site amplification corrections to the reference rock hazard. The resulting probabilistic seismic hazard map expresses peak ground acceleration at 10 percent probability of exceedance in 50 years, ranging from 0.04g to 0.09g across Kano, with the highest values at alluvial sites near the Jakara River. The study argues that code-level seismic design provisions should be adopted for critical infrastructure in Kano. Keywords: seismic hazard, PSHA, Kano, critical infrastructure, ground motion