Nowadays, risk assessment is an essential tool for risk management and risk mitigation policies since it provides an evaluation of the risk associated to a recognized threat that can cause harm or damage to humans, their structures or the environment. Risk results from the combination of three factors (UNDRO, 1982): Risk = Hazard x Exposure x Vulnerability. In this very general framework, the hazard is a measure of the likelihood of the expected size of a dangerous phenomenon in a given target area and in a given exposure time, the exposure measures the assets that are potentially at risk (both people and structures) and the vulnerability represents the degree at which the assets may be damaged due to the hazard. Of course, this represents a simplification of the reality, which does not...