Slope analysis within the Wabane caldera was carried out to establish their stability after the 20 th July 2003 landslides. A site with semi-circular fractures was selected for the installation of a vibrating wire displacement meter and a vibrating piezometer. Displacement, rainfall and pore water fluctuation were recorded from May to December 2005 in an attempt to assess the behavior of these slopes with varying rainfall intensities throughout the period. The results indicated an increase in

more »

... splacement with rainfall and pore pressure from May to September and a subsequent decrease from October to December. This demonstrates the interdependence between rainfall, pore pressure and displacement. The mean monthly rate of displacement recorded was 132.3 mm/month. The highest rate of displacement from regressive plots was approximately 0.01 mm/min for the months of August/September. These are low threshold values, and one can therefore infer that they represent the beginning of a possibly new cycle to landslides projected to occur again in the future. Prolonged rainfall and increased pore water pressure had been determined as the immediate factors responsible for the initiation of the 2003 landslides.