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The best knowledge of hazardous events and the precise mapping of the zones that they could involve are essential to plan the actions aimed at reducing the territorial vulnerability and promoting the development of a resilient community. In this framework, the main goal of the present research is to propose a quantitative spatial modeling approach that, starting from hazard indicators, defines multi-hazard indices to compare the degree of hazard among different zones allowing the establishment of intervention priorities for risk reduction. The method was applied to the case study of Ischia island, located in the north-western zone of Napoli bay (Southern Italy): indeed, the exposure to many natural hazards (seismic, volcanic, landslide, coastal erosion and marine inundation) coupled with the intense urbanization make the island a good test area to validate the methodology here proposed. Taking into account the different recurrence times of natural events, two multi-hazard indices were quantified, the total multi-hazard index that illustrates the hazard status of the territory considering all the natural events and the partial-hazard index that only takes into account those occurring yearly to decadally. Moreover, with the aim of easily and globally visualizing the hazard status of the territory, the indices were depicted into maps that could facilitate the communication to stakeholders and consequently the reduction of social vulnerability. 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. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we present an approach for evaluating landslide susceptibility in seismic areas. It is known that earthquake-induced landslide susceptibility is related to several, often interplaying, factors. Nevertheless, an effective grade-2 zonation should be characterized by a good balance between simplicity, quickness and reliability. The GIS-based procedure we present employs only three factors that we believe are the most significant in this susceptibility assessment: the type of outcropping rocks/soils, the slope angle and the MCS intensity. The local annual precipitation, certainly an essential factor, is considered here as a parameter whose seasonal pattern is constant in time and space. Each of the three parameters is expressed as a Significance percentage and the resulting Seismic Landslide Susceptibility level of an area is given by the average of the significances of the first two factors multiplied by the significance of the third factor. The procedure was set and tested on the volcanic island of Ischia (southern Italy), which was affected by several historical earthquake-induced landslides. The results of this susceptibility zonation test at Ischia show a very good match between the distribution of the sources of historical landslides and the areas we identified as the most susceptible ones. [Copyright &y& Elsevier]