Seismic Microzonation Study for Urban Hazard Assessment in Jalingo, Taraba State, North East Nigeria

Jalingo, the capital of Taraba State in North East Nigeria, is located within a tectonically active zone where occasional seismic events have been recorded, yet no formal seismic microzonation study has been conducted to guide urban development and infrastructure siting. This study conducts a seismic microzonation assessment using ambient noise measurements and shallow seismic refraction at 30 sites distributed across Jalingo urban area. Three-component seismometers acquired minimum 40-minute ambient noise records at each site, from which horizontal-to-vertical spectral ratio curves were computed. Shallow seismic refraction was carried out at 10 of the 30 sites to provide independent estimates of shallow shear wave velocity for cross-calibration. Fundamental resonance frequencies range from 1.2 to 6.5 Hz, with the lowest frequencies corresponding to sites in the Taraba River floodplain underlain by thick alluvial deposits. Peak amplification factors of 4 to 8.5 are recorded at flood-prone sites, indicating significant site response effects. Vs30 values estimated from the combined refraction and HVSR analysis range from 180 metres per second in alluvial areas to over 700 metres per second on rocky outcrops, enabling site class assignment using both EC8 and NEHRP classification schemes. The microzonation map provides a regulatory framework for building code enforcement and spatial planning in Jalingo. Keywords: seismic microzonation, HVSR, Vs30, Jalingo, urban hazard