RESILIENCE AND VULNERABILITY OF URBAN SYSTEMS. A METHODOLOGICAL PROPOSAL FOR SEISMIC RISK MITIGATION

In order to rethink the urban structure of any city, it is unavoidable to examine the safety issue, considering natural and anthropological risks and, in particular, seismic risk. The seismic protection of structures regards almost half of Italian area, and to face it properly it is essential to start suitable intervention strategies and sharp prevention actions. Therefore, it is necessary to pursue prevention and safety goals, applying norms, establishing policies and using appropriated strategies and tools typical of urban plan. The innumerable catastrophes, caused by natural events, have induced, unfortunately only of late, to shift from an emergency culture to a prevention one, from "reactive" policies to "proactive" ones. This change is strictly linked to the diffusion of paradigm of sustainability and to the widespread positioning of the mitigation of natural risks issue into the theoretical system of sustainability. So, starting from an interpretation of the city as an artificial ecosystem and from an analysis of the concept of resilience, the article suggests a reinterpretation of the concept of vulnerability as opposite of resilience, which is the system's capability to face, adapt itself and recover from the disturbing action of the earthquake In particular, it is proposed a methodological hypothesis for the knowledge of seismic vulnerability features of urban structures, which means a perfect correlation between demand produced by seismic activity and organizational spatial modality of urban system. This knowledge represents an unavoidable tool to increase system's resilience, acting on relationships among its constitutive elements (activities and spaces), in other words acting on levels of physical and functional organization of the system upon which depends its complexity, and therefore, its resilience.