In the last years, metropolitan areas are more and more exposed to natural risks often intensified by the effects of climatic changes. Clear and complete information about hazards impending on the territory is indispensable for local authorities to define efficient territorial management strategies focused on the risk reduction. A flexible hazard tool which works at different scale and with several sources of hazard is here proposed. We drew maps of monothematic and synthetic indices to describe the hazard status of metropolitan areas. A hazard hotspot map was also elaborated to identify both the areas with high hazard for the single dangerous event and the areas characterized by the concomitance of several hazards. We computed hazard indices for Napoli and Pozzuoli, a densely populated area, located in the Somma-Vesuvio and Campi Flegrei multi-source volcanic zone and also exposed to landslide, flood and coastal erosion hazard.

The sands of the Ofanto River (Southern Italy) include a volcaniclastic component represented by clinopyroxene, melanite garnet, amphibole and subordinate volcanic lithics. In order to infer the provenance of this component, we have conducted a microanalytical and isotopic study on the volcanic minerals of the sands collected in three different sites along the Ofanto River: (1) upstream sector, where only sedimentary rocks are drained; (2) middle course, along a tributary draining only the Monte Vulture volcanic rocks, (3) the mouth of the Ofanto. Moreover, minerals of the beach sands of the Tyrrhenian Cilento coast were analyzed for comparison. The microanalytical study and the Sr-Nd isotopic composition reveal the existence of two populations of pyroxenes characterized by distinct isotopic signatures and indicating a provenance from two different volcanic sources. One is confidently identifiable with Monte Vulture, and is evident in the minerals of the middle course and mouth sands. The pyroxenes of the upstream sector, isotopically similar to those of the Cilento coast, have a Campanian signature. The simultaneous occurrence of amphibole and garnet point to the explosive eruptions of Mount Vesuvius as the most probable sources of these minerals. The absence of Campanian pyroxenes at the mouth of the Ofanto River could be related to the occurrence of dams limiting the transport of solids along the river.