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

Abstract 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.

[1]  M. Marani,et al.  Tectonic, volcanic and hydrothermal features of a submarine portion of the Aeolian arc (Tyrrhenian Sea) , 1997 .

[2]  M. Rosi,et al.  Explanatory notes to the geological map , 1987 .

[3]  M. Dragoni,et al.  Modeling long-term ground deformation due to the cooling of a magma chamber: Case of Basiluzzo island, Aeolian Islands, Italy , 2003 .

[4]  M. Anzidei.  Rapid bathymetric surveys in marine volcanic areas: a case study in Panarea area , 2000 .

[5]  Giuseppe Vilardo,et al.  Geodynamic significance of the Aeolian volcanism (Southern Tyrrhenian Sea, Italy) in light of structural, seismological, and geochemical data , 2003 .

[6]  L. Beccaluva,et al.  Petrology and K/Ar ages of volcanics dredged from the Eolian seamounts: implications for geodynamic evolution of the southern Tyrrhenian basin , 1985 .

[7]  G. Gabbianelli,et al.  Tectonic and volcanic evolution of Panarea (Aeolian Islands, Italy) , 1990 .

[8]  F. Italiano,et al.  Massive submarine gas output during the volcanic unrest off Panarea Island (Aeolian arc, Italy): Inferences for explosive conditions , 2005 .

[9]  G. Chiodini,et al.  Monitoring and modelling hydrothermal fluid emission at La Solfatara (Phlegrean Fields, Italy). An interdisciplinary approach to the study of diffuse degassing , 2003 .

[10]  Studio di fattibilità , 2004 .

[11]  A. Esposito,et al.  The high resolution bathymetric map of the exhalative area of Panarea (Aeolian Islands, Italy) , 2005 .

[12]  A. Peccerillo,et al.  Petrology and geochemistry of volcanic rocks from the island of Panarea: implications for mantle evolution beneath the Aeolian island arc (southern Tyrrhenian sea) , 2002 .

[13]  F. Innocenti,et al.  Volcanism of the southern Tyrrhenian Sea and its geodynamic implications , 1973 .

[14]  F. Italiano,et al.  Geochemical investigations of submarine volcanic exhalations to the east of Panarea, Aeolian Islands, Italy , 1991 .

[15]  F. Lucchini,et al.  Explanatory notes to the geological map (1:10,000) of Panarea and Basiluzzo islands (Aeolian arc, Italy). , 1999 .

[16]  F. Italiano,et al.  Evidence of a recent input of magmatic gases into the quiescent volcanic edifice of Panarea, Aeolian Islands, Italy , 2004 .

[17]  C. Newhall,et al.  Roles of groundwater in volcanic unrest , 2001 .

[18]  S. Falsaperla,et al.  Regional stress field in the area of Stromboli (Italy): insights into structural data and crustal tectonic earthquakes , 1999 .