Geodynamics and Crustal Deformation Monitoring in the Cameroon Volcanic Line Using Continuous GNSS

The Cameroon Volcanic Line, extending from the Gulf of Guinea through western Cameroon and into the North West and Adamawa regions adjacent to North East Nigeria, represents a tectonically and volcanically active zone with implications for seismic hazard in the broader West-Central Africa region. This study applies continuous GNSS time-series analysis to characterise crustal deformation patterns along the Nigerian sector of the Cameroon Volcanic Line using five years of daily solutions from four CORS stations in Taraba, Adamawa, Cross River, and Rivers States. Daily GNSS solutions are computed using GAMIT-GLOBK software in a regional network adjustment constrained to the ITRF2020 reference frame. Velocity fields in the North American Plate-stabilised frame reveal horizontal deformation rates of 1.2 to 3.8 millimetres per year with broadly northeast-southwest directed extension, consistent with the rifting kinematics of the Cameroon Volcanic Line. Seasonal and non-seasonal non-linear position variations are modelled and their correlation with hydrological loading from GRACE gravity data is assessed. The study identifies one station exhibiting anomalous velocity deviation potentially indicative of localised fault creep near the Adamawa boundary, warranting further investigation. Results contribute to the regional tectonic velocity model and provide GNSS-based deformation baseline data applicable to seismic hazard assessment for North East Nigeria. Keywords: crustal deformation, GNSS, Cameroon Volcanic Line, geodynamics, ITRF.