The 2002-2003 submarine gas eruption at Panarea volcano (Aeolian Islands, Italy): Volcanology of the seafloor and implications for the hazard scenario

摘要

A submarine gas eruption started in November 2002 offshore of Panarea volcano (Aeolian Islands, Italy). The intensity of the gas emission and the considerable anomalies of the geochemical and geophysical parameters have alarmed the volcanological community and the Italian Civil Protection Agency on the possibility that this activity may represent a volcanic unrest at Panarea volcano. We used a high resolution Marine Digital Terrain Model (MDTM), with 0.5 m accuracy, and detailed underwater surveys by scuba diving to study the exhalation centres and the geological, morphological and structural features of the seafloor and to clarify the relationships between gas vents distribution, submarine volcanological structures and the recent deformation of this area. The underwater surveys revealed an exhalative field characterised by 21 main active gas vents and craters from metres to tens of metres in diameter, and a pervasive exhalation from the seafloor; hundreds of fossil craters associated with gas pipes and hydrothermal alteration are also present on the seafoor: craters, pipes and conduits are not associated with juvenile deposits and relate to a long standing history of gas exhalation and eruptions.We present the first geological sketch map of the seafloor surrounding the exhalative area and establish the role of NE- and NW-trending fractures as the main pathways for the gas exhalation.