A comparative geological, tectonic and geomorphological assessment of the Charlotte, Regent and Madina landslides, Western area, Sierra Leone

Abstract This work focused on three landslide events that have attracted significant public concern due to the associated calamities they recorded in 1945, 2017 and 2019, i.e. Charlotte, Regent Madina landslides, respectively. Their geology, tectonics (structural discontinuities) geomorphology, their GTG characteristics were studied establish links between them events. Field surveys conducted, particularly Charlotte landslide, where identification of geological structures was impeded an extent by its obliteration vegetation sediment accumulations relatively planar sections area. Remote sensing GIS techniques (earth imagery drone images) enhanced mapping determination landslides’ geometric geomorphic parameters. Laboratory analyses rock soil samples provided petrological characterisation used determine particle-size distribution slide-prone soil. The study indicated a change gabbroic composition, variable geomorphological characteristics, nature/pattern density discontinuities. These factors, large extent, determined nature magnitude rainfall-triggered landslides. lithology slightly differed from other two landslides higher Silica (Si) Aluminum (Al) lower iron (Fe) X-Ray Fluorescence (XRF) than rocks also revealed only tenuous correlation composition weathering depth. slope angles at prominent scarps (depletion zone) are steep (> 45 degrees) with altitudes approximately 270 m, 200 m 470 above sea level for Madina, Unlike both active, but geometrically, area, length run-out distances high variance coefficient equals 1. Information derived this can help understand spatial variation develop susceptibility map.