The hazard indices as a tool to support the territorial planning: The case study of Ischia island (Southern Italy)

The municipalities of Serrara Fontana, Barano d'Ischia and Casamicciola Terme show the highest total multi-hazard index of the study area, all the other municipalities display a value (always exceeding 0.5) that, although lower than in the previous three, signifies that the entire island needs attention with regard to natural hazards. The partial multi-hazard index confirms the highest value for Serrara Fontana and Barano d'Ischia. Multi-hazard hotspots, identified at the censual district scale for the Forio d'Ischia municipality, enlighten the areas where a comprehensive risk assessment is needed. We also took advantage of spatial and temporal analysis in order to compare the evolution of population and urban development to spatial distribution of hazard zones over the last 80 years. This analysis evidenced that the urban development was insensitive to the dangers impending on the territory, as the expansion in the zones with medium-high level of hazard testifies. Because of this, the present status of the island postulates the urgent need of integrating disaster risk reduction into future spatial planning.