Decision Support Tools for Urban Contingency Policy. A Scenario Approach to Risk Management of the Vesuvio Area in Naples, Italy

Contingency management, in particular the management of unanticipated events outside the control of an ordinary planning system has, in the last 50 years, become an important and frequently debated issue in the scientific literature on complex systems management under risk conditions. The urban system can be regarded as such an open complex system where external events, not always foreseeable with a closed system's model, may strongly impact on the internal dynamics of an urban area. Conventionally, planning the future presupposes collecting information and analyzing it rationally in order to control for unexpected contingency events. But it is an important question in the field of urban planning how proper strategies can be developed to deal with external uncertainty and shocks that transcend the imagination of policy-makers. How should decision-makers respond to such unforeseen jumps in a system? The aim of this article is to present and apply a new decision support method based on the future studies literature, with the aim to help decision-makers in the strategic management of uncertainty and risk in order -(Godet, 1987). In particular, we here deploy the scenario methodology in combination with multicriteria analysis and fuzzy set theory, as a useful learning tool for the governance of complex dynamic systems. In current debates on policy-makers' possible reactions to uncertainty (e.g., in the context of sustainability strategies), very often the socalled 'no regret' principle is advocated. The validity of this approach is tested, in the context of the present article, on real-world threats in the Vesuvio volcanic area in the vicinity of the densely populated city of Naples, Italy. Four different policy scenarios are developed with the purpose to examine, control and reduce the risk for the people concerned in case of a future volcanic eruption and to lay, at the same time, the foundation for a drastic rehabilitation of the entire metropolitan area. scientific to anticipate the extraordinary events correctly in order to act more effectively