Rock Fall Analysis on the City of Lubango, SW Angola

Abstract

A study of the rock falls conditions of an area in the city of Lubango (Angola) was carried out. The upper parts of the studied slopes are constituted by whitish and grayish quartzites and pink, brown or reddish sandstone from the Chela Group of the Precambrian age. Debris deposits can be found at the toe of the slope. The slope movements are more frequent during the rainfall period, which run from October through April. A lithological and volumetric characterization of the rock fall blocks present on the study area was carried out. The software program Rocfall of the Rocscience packages was used to study the rock fall paths. The rocks location, mass and velocity as well as the properties of the slope material were defined and the rock falls trajectories were studied. The possible rock fall trajectories on the slope can cause significant damage to homes. According to the stability study, some mitigation and prevention procedures were suggested in order to allow human occupation of the Lubango’s urban area adjacent to the slopes.