Massive submarine gas output during the volcanic unrest off Panarea Island (Aeolian arc, Italy): Inferences for explosive conditions

The possibility of understanding natural processes leading to explosive events in volcanic systems provides advantages for a better management of possible volcanic crises. On account of the possibility of the occurrence of other phenomena, such as tsunamis, the explosions driven by submarine volcanic systems are of particular interest, although little investigated. The recent sudden increase in the degassing activity of the submarine geothermal system of Panarea Island (Aeolian arc), has allowed us to better understand the way in which the quiet degassing activity of a submarine hydrothermal system may develop if new magma or magmatic gases feed it. We focused our investigations on the crater-shaped area where the volcanic crisis started, with the aim of evaluating whether the crater was formed by an explosive event or by sediment erosion due to the intense gas flow rate. The calculated energetic conditions, coupled with the computed physicchemical state of the fluids at the level of the deep reservoir, provided the theoretical boundary conditions of the occurred event, while suggesting that a low-energy explosion was responsible for producing the crater at the sea bottom.