Deception Island, Antarctica (62°57’S, 60°38’W)
DECEPTION ISLAND, ANTARCTICA (62°57’S, 60°38’W) All the information provided below is modified from the following publication: SMELLIE, J.L., LÓPEZ-MARTÍNEZ, J., THOMSON and others. 2002. Geology and geomorphology of Deception Island. BAS GEOMAP Series, Sheets 6-A and 6-B, 1:25 000, supplementary text, 77 pp. Cambridge, British Antarctic Survey. The text included here form the core of a hazards assessment and mitigation section within a Management plan for Deception Island. It is currently being considered by Antarctic Treaty nations. Volcanic history The eruptive history of Deception Island can be described in four major phases: Phase 1. The earliest phase, comprising subaqueous eruptions, constructed at least 80 % of the volcanic edifice and was responsible for its overall form as a volcanic shield with gentle surface gradients. Because it is entirely submerged, it has not been examined. By comparison with uplifted and exposed oceanic volcanoes elsewhere, it is inferred to be formed of pillow lava and hyaloclastite breccia, which would have formed non-explosively mainly during subaqueous effusion. Phase 2. The shoaling and early subaerial emergence of the volcano is represented by rocks of the Fumarole Bay and Basaltic Shield formations, respectively. Those were formed by lava fountaining from several, possibly co-eruptive centres in shallow water, and a small subaerial edifice constructed during low-energy explosive eruptions and lava effusion. Phase 3. The sudden connection of magma between two magma chambers beneath Deception Island probably triggered the caldera-forming eruption on Deception Island. That eruption is the only large-scale event known to have affected the volcano, and the eruption characteristics (dynamics, dominant lithofacies, etc) are significantly different from other eruptions on the island.
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