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Stable open vent behaviour sustained over decades at Mt Michael, South Sandwich Islands, revealed by in situ and satellite observations

Emma Nicholson 1,2, Joao Lages3, Adam Cotterill2, Alessandro Aiuppa3, Marcello Bitetto3, Diego Coppola4, Marie Edmonds5, Marco Laiolo4, Francesco Massimetti4,6, Carla Perez7, Ben Wallis8, Kieran Wood9, Ben Esse10

  • Affiliations: 1University of Waikato, Hamilton, New Zealand; 2Department of Earth Sciences, University College London, London, UK; 3Dipartimento Di Scienze Della Terra e del Mare, Università di Palermo, Palermo, Italy; 4Dipartimento Di Scienze Della Terra, Università Di Torino, Turin, Italy; 5Department of Earth Sciences, University of Cambridge, Cambridge, UK; 6Instituto de Geofísica, Universidad Nacional Autónoma de México, Mexico; 7Independent, Ecuador; 8Ocean Expeditions; 9School of Engineering, University of Manchester, Manchester, UK; 10Earth and Environmental Sciences, University of Manchester, Manchester, UK

  • Presentation type: Talk [Invited]

  • Presentation time: Friday 10:30 - 10:45, Room S150

  • Programme No: 3.17.1

  • Theme 3 > Session 17

Abstract

Open vent volcanoes present unparalleled opportunities to observe volcanic processes. Mt Michael is an enigmatic mafic open vent volcano in the South Sandwich volcanic arc. Recurrent thermal hotspots in multispectral satellite imagery have motivated speculation around the existence of a persistent lava lake. We explore temporal variability in open vent behaviour at Mt Michael from the ground and from space. We combine in situ observations of gas composition, emission rate, and thermal imaging with long-term records of SO2 and thermal emissions from satellite remote sensing to evaluate in form what magma is present at the surface and the stability of that geometry over time, determine whether gas and thermal emissions are coupled over timescales of months to years, and explain these observations in the context of the transport and storage of magma and volatiles. We measured an SO2 flux of 135 t/d in November 2022, consistent with a concurrent satellite-based (TROPOMI) flux 120 ± 40 t/d. More energetic pulses occurred periodically every few minutes, with peaks in SO2 flux up to 605 t/d. Deconvolving magmatic and low-temperature fumarole sources within our volcanic gas timeseries, we derive molar CO2/SO2 ratios of 2.1 and 5.0, respectively. Multiple vents contribute to thermal radiative power, varying between 1 and 3 in number but always in the same locations, suggesting a well-established shallow conduit geometry. We suggest that stable open vent behaviour at Mt Michael has been sustained over decades and is transitional between a classic small lava lake and a multi-vent open system volcano.