La Fossa Caldera breaching and submarine erosion (Vulcano island, Italy)

La Fossa Caldera (LFC) on Vulcano island, in the Aeolian archipelago (Italy), is a multi-collapse caldera whose north-eastern part lies underwater. Through the integration of marine geophysical surveys and sampling carried out in the last decade, its submarine extension and offshore areas have been reconstructed in unprecedented detail. Strong erosive processes breached the submarine portion of LFC and gradually dismantled the caldera rims and infill, leading to the emplacement of a wide volcaniclastic fan from the base of LFC down to over 1000 m. The bathy-morphologic setting, seismoacoustic facies and analyses of sediment samples from the fan, together with volumetric considerations, suggest that this feature is the pathway/deposit of submarine unconfined gravity flows and turbidity currents deriving from the gradual dismantling of LFC. Submarine erosive processes are still active and the progressive erosion of the northern caldera sector threatens the stability of the active La Fossa Cone and the nearby coastal settlements.