Landslide in parts of southwestern Nigeria

Abstract

Landslides represent “structural failures” with great risk to the environment, and this makes the study of the mechanism of formation of landslides very important. Most parts of the Okemesi ridge are inherently dangerous areas, at high risk of sliding. This research is one of the first detailed geological investigations of landslides in this area. This research evaluates the importance of the lithological, structural and geomorphological factors to landslide activities in parts of southwestern Nigeria with the aim of designing a susceptibility map which is intended to serve as an early warning and mitigation measures. The result revealed that the latest landslide was caused by the release of intensely fractured rocks along adjacent blocks of a fault plane, and prevalent tectonic stress condition set the stage for the landslide, while slope instability in conjunction with prolonged high-intensity rainfall triggered the movement. The most susceptible area of landslide is within the slope angles of between 45° and 75° with an elevation of between 514 and 666 m. The research further revealed that the landslide occurred about 500 m to the road. The landslide-prone location is within the 0–200 m from the hill; hence, human settlements and activities should be sited at least 500 m away from the hill.