The mechanisms and characteristics of a complex rock-debris avalanche at the Nigeria–Cameroon border, West Africa

摘要: Abstract We describe a rock-debris avalanche which occurred on steep, symmetrical ridges resulting from fracture-controlled erosion in the valley. The fractures were partially filled with clayey materials, probably derived weathering of feldspar. Major fault lines trending N–S located less than 7 km landslide location. Exposed sections revealed that basal rock units migmatites and gneisses, while upper section consisted porphyritic granites. A failure residual clay-rich soil, composed visible crystals feldspar mica, is thought to have triggered long chain events led development avalanche, diverted course rivers area was characterised by shallow water table dry season (2 3 m) this might facilitated formation slip surface at regolith–rock interface. Field observations laboratory analysis showed regolith failed first because high pore pressure build-up rapid reduction shear resistance; then fractured units. slope movement perpendicular foliation gneissic rocks, contributed mobility. Of interest changing saturation level constant relative density about 32% resulted either complete or limited liquefaction, indicating mechanism depended moisture content regolith.