Risk assessment system of natural hazards: A new approach based on fuzzy probability

This paper presents a system for assessing the risk of natural disasters, particularly under highly uncertain conditions, i.e. where neither the statistical data nor the physical knowledge required for a purely probabilistic risk analysis are sufficient. The theoretical foundation of this study is based on employing fuzzy set theory to complement the probability theory with an additional dimension of uncertainty. This would allow for expressing the likelihood of natural hazards by fuzzy probability. The fuzzy probability is characterized in terms of possibility–probability distributions, for which a new approach has been developed. The new approach has been compared with an alternative approach. Moreover, uncertainties about the correlation of the parameters of hazard intensity, damage and loss, i.e. vulnerability relations, have been considered by means of fuzzy relations. The composition of fuzzy probability of hazard and fuzzy vulnerability relation yields the fuzzy probability of damage (or loss). The system has been applied for assessing the earthquake risk in Istanbul metropolitan area.