Deception Island, Antarctica: eruptive dynamics and volcanic hazards in a post-caldera monogenetic volcanic field

Abstract

Deception Island (DI) is an active Quaternary volcanic caldera of the South Shetlands Archipelago (Antarctica) (Fig. 1a, b).Post-caldera volcanism includes over 30 eruptions during the Holocene (e.g. Orheim 1972) with more than 20 volcanic episodes registered over the past two centuries (Orheim 1972; Roobol 1982; Smellie et al. 2002) including the eruptions of 1967, 1969, and 1970 (Fig. 1c). These eruptions, together with the 1992, 1999 (Ibáñez et al. 2003), and 2014–2015 (Almendros et al. 2015) unrest episodes, demonstrate that the volcanic system under DIis still very active and that the occurrence of a new eruption is likely. Recent post-caldera volcanism is dominated by hydromagmatic eruptions, with the water source being from Port Foster Bay seawater, from the underground aquifer and water from the glaciers (Baker et al. 1975; Smellie 2002; Pedrazzi et al. 2014). Even small-volume eruptions become highly explosive when located on waterlogged shorelines, or beneath ice caps (Baker et al. 1975; Smellie 2002; Pedrazzi et al. 2014). A detailed field revision of the historical (1829–1970) hydrovolcanic post-caldera volcanism at DI was carried out, with the aim of understanding how the location of a potential new eruptive vent can control magma-water interactions, and the related hazards to be expected during a new eruption on the island.