Hazard is one of the components that contribute to the definition of risk induced by natural disasters, and it is defined as the probability that a catastrophic phenomenon may occur in a defined area during a given period of time. Elements at risk include population, properties, buildings, transport infrastructures and economic activities. Vulnerability represents the degree of loss of an element or group of elements at risk, as a consequence of the occurrence of a natural phenomenon of a given intensity. The risk corresponds to the expected value of the loss and can be expressed as the product of three terms: hazard, vulnerability and value of the elements at risk (Varnes and IAEG Commission on Landslides, 1984).