Fig 1.
A) Sketch shadow relief map of the Campi Flegrei volcanic field. Vent locations adopted for numerical simulations of PCs at Campi Flegrei are reported: fourteen possible eruptive vents are considered, i.e.: six located within the source area of the most recent eruptions, the other ones in the area with the highest horizontal (four vents) and vertical (four vents) deformation during recent bradyseismic events (see text for further explanation). B) Example of the motion of a material point along a digitalized 3D surface considered in the present model (see "Computational model" section for explanation). The Campi Flegrei Digital Elevation Model is courtesy of Laboratory of Geomatica e Cartografia, INGV-OV Naples. C) Sketch of the flow front moving on the digitalized 3D surface subdivided in triangles that are equilateral of side 250 m in plain view.
Fig 2.
Model results for VEI 2 eruptions at Campi Flegrei.
A) Maximum limit (red line) reached by the PCs during the 1538 AD Monte Nuovo eruption, representative of VEI 2 events at Campi Flegrei; B) typical exposure of the Monte Nuovo PC deposits at about 0.5 km from the vent; C) hazard map of conditional probability (i.e., probability of a given point to be affected by the passage of PCs in the case of an eruption of a given VEI) and D) the associated maximum dynamic pressures (expressed in Pa) for moderate- to high-particle concentration PCs; E) hazard map of conditional probability and F) the associated maximum dynamic pressures for dilute PCs (see text and Tables 1 and 3 for the PC characteristics adopted in the simulations). Levels of damage associated to different values of dynamic pressure (after Valentine 1988): 500 Pa = poor damage; 5,000 Pa = window failure, lower limit for severe damage and collapse of weak non-aseismic buildings; 10,000 Pa = limit for severe damage and collapse of weak aseismic buildings; 25,000 = limit for collapse of strong aseismic buildings and volcanic masonry walls. The urbanization pattern is also shown in C-F. The Campi Flegrei Digital Elevation Model is courtesy of Laboratory of Geomatica e Cartografia, INGV-OV Naples.
Fig 3.
Model results for VEI 3 eruptions at Campi Flegrei.
A) Maximum limit (red line) reached by the PCs during the ~ 3.9–3.7 ka Averno eruption, as example of VEI 3 events at Campi Flegrei; B) typical exposure of the Averno PC deposits at about 1.5 km from the vent; C) hazard map of conditional probability and D) the associated maximum dynamic pressures (expressed in Pa) for moderate- to high-particle concentration PCs; E) hazard map of conditional probability and F) the associated maximum dynamic pressures for dilute PCs (see text and Tables 1 and 3 for the PC characteristics adopted in the simulations). Levels of damage associated to different values of dynamic pressure as in Fig 2. The urbanization pattern is also shown in C-F. The Campi Flegrei Digital Elevation Model is courtesy of Laboratory of Geomatica e Cartografia, INGV-OV Naples.
Fig 4.
Model results for VEI 4 eruptions at Campi Flegrei.
A) Maximum limit (red line) reached by the PCs during the ~ 4.1–3.8 ka Astroni eruption, as example of VEI 4 at Campi Flegrei; B) typical exposure of the Astroni PC deposits at about 1.5 km from the vent; C) hazard map of conditional probability and D) the associated maximum dynamic pressures (expressed in Pa) for moderate- to high-particle concentration PCs; E) hazard map of conditional probability and F) the associated maximum dynamic pressures for dilute PCs (see text and Tables 1 and 3 for the PC characteristics adopted in the simulations). Levels of damage associated to different values of dynamic pressure as in Fig 2. The urbanization pattern is also shown in C-F. The Campi Flegrei Digital Elevation Model is courtesy of Laboratory of Geomatica e Cartografia, INGV-OV Naples.
Fig 5.
Model results for VEI 5 eruptions at Campi Flegrei.
A) Maximum limit (red line) reached by the PCs during the ~ 4.1 ka Agnano Monte Spina eruption, as example of VEI 5 at Campi Flegrei; B) typical exposure of the Agnano Monte Spina eruption PC deposits at about 2 km from the vent; C) hazard map of conditional probability and D) the associated maximum dynamic pressures (expressed in Pa) for moderate- to high-particle concentration PCs; E) hazard map of conditional probability and F) the associated maximum dynamic pressures for dilute PCs (see text and Tables 1 and 3 for the PC characteristics adopted in the simulations). Levels of damage associated to different values of dynamic pressure as in Fig 2. The urbanization pattern is also shown in C-F. The Campi Flegrei Digital Elevation Model is courtesy of Laboratory of Geomatica e Cartografia, INGV-OV Naples.
Fig 6.
Model results for VEI 6 eruptions at Campi Flegrei.
A) Maximum limit (red line) reached by the PCs during the ~14.9 ka Neapolitan Yellow Tuff eruption; B) typical exposure of the Neapolitan Yellow Tuff PC deposits at Posillipo, along the southeastern caldera rim; C) Hazard map of conditional probability and D) the associated maximum dynamic pressures (expressed in Pa), for VEI 6 PCs (see text and Tables 1 and 3 for the PC characteristics adopted in the simulations). Levels of damage associated to different values of dynamic pressure as in Fig 2. The urbanization pattern is also shown in C-F. The Campi Flegrei Digital Elevation Model is courtesy of Laboratory of Geomatica e Cartografia, INGV-OV Naples.
Table 1.
Reference eruptions at Campi Flegrei.
Table 2.
Definition of notations through the text.
Table 3.
Input parameters for PC simulations.
Fig 7.
Examples of the different impact of relatively small (VEI = 3) PC events from two different vents located in contiguous areas (i.e., eastern Agnano plain and Pisciarelli).
Left bar shows the conditional probability values. PC input data: initial velocity: 30 m/s; flow height: 10 m, viscosity = 5 Pa/s; yield strength = 0; density = 50 kg/m3. The Campi Flegrei Digital Elevation Model is courtesy of Laboratory of Geomatica e Cartografia, INGV-OV Naples.
Fig 8.
Example of a small (VEI≤3) PC event from a vent located near the eastern margin of the caldera (i.e., Bagnoli-Fuorigrotta plain).
The presence of road and railway tunnels (1, 2, 3) connecting the Phlegraean area with the city of Naples (Napoli), allows the PC to bypass the barrier of the caldera wall and impact the city center. Left bar shows the conditional probability values. PC input data: initial velocity: 20 m/s; flow height: 5 m, viscosity = 5 Pa/s; yield strength = 0; density = 50 kg/m3. The Campi Flegrei Digital Elevation Model is courtesy of Laboratory of Geomatica e Cartografia, INGV-OV Naples.
Fig 9.
Combined hazard from PCs (red: areas exposed to the passage of PCs with ≥5 kPa maximum dynamic pressure, corresponding to severe building damage or collapse) and concomitant fallout (yellow: areas with at least 10% probability of exposure to critical tephra thickness for roof collapse;) in case of a VEI 5 eruption that may occur from any vent within the Campi Flegrei caldera, here considered as conservative upper limit scenario.
The Campi Flegrei Digital Elevation Model is courtesy of Laboratory of Geomatica e Cartografia, INGV-OV Naples.