Some considerations on available approaches to risk mitigation.

In many parts of the world, society is seriously threatened by several types of dangerous phenomena (either natural or manmade), such as hurricanes, tsunamis, floods, landslides, earthquakes, and fires. Each phenomenon shows peculiar characteristics-from the triggering to the final stages-and requires specific actions of risk management, including identification and analysis, monitoring, modelling and earlywarning. When a given element at risk (e.g. a building, a village, a factory, a stretch of highway, a power plant) is threatened by different types of phenomena, the evaluation of the overall risk and its mapping is even more complex. The understanding of the triggering mechanisms is fundamental for predicting the time of occurrence of a given phenomenon (usually expressed in terms of temporal hazard). In addition, spatial hazard evaluations are required to predict the area potentially affected by the phenomenon, by taking into consideration its presumable evolution from the source to the affected area. As concerns specific risk evaluation, and related assessment of impact or damage potential, a further issue to be considered concerns the vulnerability of the elements at risk. This analysis can include social and cultural aspects as well as environmental, physical, and structural components. Risk assessment should eventually provide authorities with supporting information to target mitigation and response actions adequately, including indications on where, when, and how a given set of elements at risk might be affected by a certain impact scenario. As social systems may react in case of disaster/emergency situation in different ways, social structures and varying aspects of resilience must be considered to differentiate situation-specific vulnerability patterns on a local scale, to better evaluate mitigation options and plan response actions. Learning from past disasters, as well as envisioning future developments of social systems and corresponding adaptation of disaster management processes, is essential in minimizing impacts of future events. Though, it is not feasible to achieve zero risk. Aiming at minimizing the residual risks, innovative approaches range from integrated modelling and monitoring of hazardous phenomena, to evaluating related vulnerability patterns, to land use planning, knowledge dissemination and risk communication, to realizing remedial measures.