Hazard Scenarios Related to Submarine Volcanic-Hydrothermal Activity and Advanced Monitoring Strategies: A Study Case from the Panarea Volcanic Group (Aeolian Islands, Italy)

Table 2

Hazard scenarios connected to Panarea activity.

Hazard scenario	(1) Ordinary venting	(2) Gas burst	(3) Eruption (Drauto-type)
Probability of occurrence	Permanent.	High.	Low.
Recurrence interval	Permanent.	One event per 65/70 years [20].	Unknown.
Hazard	Low.	High.	Very high.
Extremely dangerous phenomena	Constant release of CO2 and H2S-rich gases.	Poisonous gas clouds (toxic clouds); tsunamis.	Intermittent eruptive columns; tephra fallout; pyroclastic density currents; toxic clouds; tsunamis.
Mitigation measurements	Near real-time monitoring of CO2 and H2S concentrations in the seawater surface/atmosphere.	Evacuation of Panarea villages located downwind to the gas burst area; interdiction of tourist activity and marine navigation in the gas burst area; near real-time monitoring of the gas output and CO2 and H2S concentrations.	Evacuation of the whole Panarea island and the coasts of the surrounding Aeolian Islands; interdiction of marine navigation and tourist activity.