Methodology for quantitative landslide risk analysis in residential projects

This paper provides a quantitative assessment for the hazard, the vulnerability and the risk associated to slope instability as a tool for urban planners and policy makers. Analysis methodologies and overall numerical procedures are presented in detail. In order to assess a hazard, which is expressed as a temporal probability, FOSM technique was used along with Rosenblueth's point estimate method. Reliability index (β) was used as a standard measure to compare the results assessed with other information presented in published literature for a number of geotechnical projects. Concerning the analysis of vulnerability, a new approach was proposed by combining local methodology for seismic vulnerability designed for buildings in Medellin with generic analysis methodology for vulnerability of people when exposed to landslides. The risk was assessed by a simple mathematical crossing between hazard and vulnerability. A database of 120 residential projects located on natural slopes in the city of Medellin (Colombia) was used for the analysis. The results were presented as FN charts relating the calculated frequency of landslides to the number of potential life or economic losses.