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Volatile contents and quenching conditions during the 2021-2022 eruption of Hunga volcano, Tonga

Mila Huebsch1, Mathieu Colombier2, Joali Paredes-Mariño1, Shane J. Cronin1, Jie Wu3, Ingrid Ukstins1, David Adams1, Geoff Kilgour4, Alex RL Nichols5, Annahlise Hall1, Annaleise Klein6, Benedicta Arhatari6, Andrew Stevenson6, Sung-Hyun Park7 and Taaniela Kula8

  • Affiliations: 1University of Auckland, School of Environment, Auckland, New Zealand; 2Ludwig Maximilians University of Munich, Department of Earth and Environmental Sciences, Munich, Germany; 3University of Otago, Department of Geology, Dunedin, New Zealand; 4Te Pū Ao | GNSScience, Wairakei Research Centre, Taupo, New Zealand; 5University of Canterbury, Christchurch, New Zealand; 6Australian Nuclear Science and Technology Organization, Clayton, VIC, Australia; 7Korea PolarResarch Institute, Incheon, Korea, Republic of (South); 8Government of Tonga,Tonga Geological Services, Nuku`alofa, Tonga

  • Presentation type: Talk

  • Presentation time: Tuesday 16:15 - 16:30, Room S150

  • Programme No: 3.2.11

  • Theme 3 > Session 2

Abstract

The 2021-2022 eruption of Hunga volcano (Tonga) began with weak Surtseyan phases and culminated in a climactic submarine Plinian explosive event and caldera collapse on 15 January 2022. Here we present new insights into the conditions and depths of magma quenching, as preserved by samples spanning stratigraphic units: i) lapilli and bombs from pre-climactic float pumice rafts (stages 1 and 2; Tongatapu); ii) the first lapilli fall from the climactic event (stage 3; Tongatapu); and iii) dense bombs from subsequent waning activity (stage 10; inner caldera rim). Geochemical compositions were determined using Electron Probe Micro-analysis. Fourier Transform Infrared Spectroscopy (FTIR) was performed for quantification of dissolved volatile concentrations, as well as Micro-Computed Tomography for 3D textural analysis, at the ANSTO Australian synchrotron. Lapilli form three main classes: i) dense glass, ii) dark pumice and iii) light pumice, with breadcrust rinds common. Glass-FTIR results span 0.1-1.8 wt% H2Ot. Secondary hydration of H2Om is negligible for subaerially deposited stage 1-3 and minor for stage 10. Plagioclase rim thermometry (Putirka 2008) indicates final crystallization temperatures of 1100-1150 C. Saturation pressures (MagmaSat; Ghiorso and Gualda, 2015) range from ~0.1-5 MPa for the pre-climactic stages, ~2-12 MPa for the climactic onset, and ~7-15 MPa for the waning stage. Corresponding depths show quenching in confined conditions within the edifice and particle textures suggest that this occurred in contact with external water. Ongoing work includes modelling of 3-phase magma viscosity, as important context for the multidisciplinary study of this enigmatic eruption and potentially common, hazardous eruption style.