The Antimilos Volcanic Group with emphasis on its submarine volcanoes, Aegean Sea

The Antimilos volcanic field of the Aegean Volcanic Arc is studied, based on an oceanographic survey off the northwestern margin of Milos Island, conducted onboard R/V Meteor, comprising high resolution bathymetric data, AUV (Autonomous Underwater Vehicles) operations and seismic parasound profiles. The scope of the paper is to describe the three submarine volcanic cones adjacent to Antimilos Island and the interaction of volcanism and tectonics in the Milos–Antimilos region. The results comprise a bathymetric map and a morphological slope map, utilizing a 5-metre grid interval. A morphotectonic map of Antimilos Island was produced, depicting the three submarine volcanic domes and a hummocky relief that extends northwestward into the Myrtoon Basin to depths of up to 800 m. NW–SE fault zones delimit the tectonic graben between the Cycladic plateau and the western Ridge, hosting the volcanic features and a 72 km 2 hummocky area with VDA deposits representing some recent sliding hazard events triggered by earthquakes. A prominent ENE–WSW fault delimits the Antimilos volcanic field from the NW Milos structure with disruption of the shelf break. The shelf area at 130–150 m depth is well developed around Antimilos Island and on top of the two shallow submarine volcanic cones at least during the last three low-stand periods, indicating their onshore/offshore evolution. The geological hazard of the studied area comprises earthquakes of magnitude Mw 6.0–6.6, submarine landslides with extended VDA deposits and volcanic activity related to the ongoing intense submarine hydrothermal vents.