The key role of hazard indices and hotspot in disaster risk management: the case study of Napoli and Pozzuoli municipalities (Southern Italy)

Figures & data

Table 1. Summary of the methodologies designed to assess single hazards used for calculation of hazard indices and hotspot map.

Type of hazard			Methodology	Reference
Volcanic	Pyroclastic Fall	Roof collapsing threshold (300 kg/m3)	For Campi Flegrei and Somma-Vesuvio, the roof collapsing isopach of the Plinian and sub-Plinian eruptions of the last 10 ky, exceeding the maximum sustainable loading, was selected.	Lirer et al. (2001); Lirer et al. (2010)
		Spatial frequency of overload	The intersection of the roof collapsing isopaches allowed to identify the different spatial frequency (number of events occurring in the same area) of exposed area.
	Pyroclastic Density Current (PDc)	Vent Opening Probability (VOP)	The hazard related to pyroclastic density current (PDC) at Campi Flegrei is based on the VOP and the spatial frequency of PDC invasion. The territory is discretized in cells and the presence/absence of geological, geochemical and geophysical indicators was used as key element for the VOP assessment.	Alberico, Lirer, Petrosino, and Scandone (2002)
		Invaded area	The invaded area was assessed through three step: (a) the ‘energy cone’ model (Malin & Sheridan, 1982), for an eruption with Volcanic Explosivity Index = 4, was simulated in each cell of the Campi Flegrei and the boundary of maximum invaded area was outlined. (b) for Campi Flegrei a weight corresponding to the VOP was assigned to the single invaded area; (c) the overlay of all invaded areas made it possible to define the spatial probability of invasion by PDC. Similarly, for the Somma-Vesuvio one simulation with VEI = 4, located in the Vesuvio crater, was realized but the invasion areas of the three main eruptions of the last 10 ky (Avellino, 79, 472 A.D.) were also considered.	Lirer et al. (2010)
Landslide			The methodology is based on two intermediate maps: (a): probabilistic assessment and consequent mapping of landslides detachment susceptibility: landslide inventories and photo-interpretation were used to assess some parameters relevant to the triggering of mass movements (slope gradient -S-, thickness of pyroclastic cover -T-, distance to tracks -D-, land use -L-); and (b) runout susceptibility. The analysis of run-out distance and drop height of past landslide allowed the identification of the angle of reach (Heim, 1932) and consequent drawing of the landslide ‘runout susceptibility map’.	Calcaterra, Parise, and Palma (2003)
Flood			The geometrical model of stream channels (obtained by GPS measurement of river courses and basin morphologies) and the hydrological model of basins make it is possible to provide simulations and hydraulic models. Considering a scheme of one-dimensional permanent motion, the simulations are carried out through the use of the calculation code HEC-RAS (Hydrologic Engineering Center – River Analysis System). Using a Digital Elevation Model (DEM) the areas affected by flooding are achieved.	Basin Authority of Central Campania (B.U.R.C. n ° 33 21/05/2012)
Coastal Erosion			The methodology is based on two intermediate maps: (a) A landslide detachment susceptibility map for cliffs is obtained through a field geological survey aiming at the evaluation of the Geological Strength Indexes for cliffs (GSI – Hoek, 1994; Hoek & Brown, 1997; Hoek & Marinos, 2000; Hoek, Marinos, & Benissi, 1998; Marinos & Hoek, 2001; Marinos, Marinos, & Hoek, 2005). This index estimates the strength of rock masses obtained through the assessment of the frequency of discontinuities and their features (e.g; roughness, weathering, presence of fillings), (b) runout susceptibility map that considers exposed to hazard the accumulation zones of past coastal landslides prolonging to sea the class of landslide detachment susceptibility assessed on land (view Main Map).	Basin Authority of Central Campania (B.U.R.C. n ° 33 21/05/2012)

Figure 1. Geo-lithological and structural sketch map of the study area.

Figure 2. Maps displaying natural hazards characterizing the Napoli and Pozzuoli municipalities: (a) volcanic hazard; (b) seismic hazard; (c) landslide hazard; (d) flood hazard; (e) coastal erosion hazard. On the bottom right of the figure, the shaded relief of Campania Region shows the two municipalities in a wide territorial setting.

Figure 3. Comparative diagrams between Vs values obtained using empirical correlations NSPT-VS and using correlations with Neapolitan lithotypes.

Figure 4. Hotspots map displaying both areas affected by high hazard for the single dangerous event and areas characterized by the concomitance of two or more hazards.

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