The weathering mechanism of rocks exposed under the same conditions on the Bamenda Mountain is not well understood. The aim of this study is to characterize basalt, trachyte and rhyolite and their products on the geochemical and geotechnical aspect. Here three wells were hand dug on rocks developed on basalt, trachyte and rhyolite and studied. The results showed that, Ki values (0.34-6.57) indicate SiO2 are more leached on soils developed on basalt than those on trachyte and rhyolite. CIA (72.62-97.8) and CIW (72.76-98.8) indicate an advanced to extreme chemical weathering in this environment, with rhyolite and trachyte more weathered than basalts. Soils formed on basalt have ICV >1 signifying they are young and immature, while those on trachyte and rhyolite ICV =0.3-0.5 indicate intense chemical weathering. Al (EFAl=1.5) and Fe (EFFe=1.3) are enriched in the soils and while SiO2, Na, K, Ca and Mg are depleted in the soils profile as one moves upward. Geotechnically, these soils are predominantly silts, well graded, less plastic (LI<0), plastic (CI>1) to moderately plastic (PI=7.2-15.8). Soils developed on rhyolite have high clay content MBV= 3.3-8, but low water content (10-42%). Texturally, these soil are silty loam, loam to sandy loam soils. Soil strength of the soils is low: cohesion (<0.5bar), angle of internal friction (10-43°), with shallow landslides (1-2m) more likely to occur on trachyte and on rhyolites.

The Bamenda Mountain (with over 250,000 inhabitants) is one of the strato-volcanoes along the Cameroon Volcanic Line (CVL) with an accidental landscape. This area is frequently affected by landslides, which most at times result in destruction of property and loss of lives. An informative value statistical method using GIS is use to prepared a landslide susceptibility map for the Bamenda Mountain area as well as a quantitative and qualitative risk assessment. This is aimed at revealing areas where future landslide would occur and potential loss. Nine landslide controlling factors including; slope, slope orientation (aspect), curvature, stream density, proximity to roads, geomorphology, proximity to streams, geology and land use were use in the model. A total of 64 slides were inventoried in the area and use to prepare the landslide density map. The weighted informative values for the combined factor and landslide density were used to prepare the landslide susceptibility map for the area. The most significant landslide causing factors in this area are; slope, stream density and slope aspect. The susceptibility map was classified into very high (17.8%), high (25.9%), moderate (33.6%) and low (22.7%). The validated model using the success rate curve indicates that the area under curve is 0.823 and predicts landslides at 82.3% in relatively high classes. Landslide risk assessment in the area indicates 406 buildings, 2,436 people, 1,291.1km of roads, 2152 ha of farmland and an approximate USD83,540,000 worth in assets are expose to high and very high risk. This approach can be implemented in other areas along the CVL to map and assess landslide risk.