Stability analysis of a slip-debris flow in the Ogbajala Hills of Benue State, Nigeria

A slip-debris flow occurred in the Ogbajala Hills of Benue State on 3 September, 1987 after three days of consecutive rainfall. Field measurements of the landslide showed that the slip originated on the upper one-third of the hill at a depth of 1.37 m and extended uniformly to about 50 m downslope before turning into a flow.Stability analysis of the slip using infinite slope analysis yielded a slip surface depth of 1.4 m with a perched water table that rose seven-tenths (0.7) into the thickness of the slipped soil before failure. These analysis results agree closely with field measurements and give an insight into the water table conditions that led to the failure.