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The Chronology of the 15 January 2022 Hunga Eruption revealed through eye-witness descriptions, tephra and tsunami deposition

Joali Paredes-Mariño1, Shane J. Cronin1, Folauhola Latu'ila2, Pupunu Tukuafu2, Nikolasi Heni2, Jie Wu3, Kyle Hamilton4, Ingrid Ukstins1, Mila Huebsch1, Taaniela Kula2

  • Affiliations: 1School of Environment, The University of Auckland, Auckland, New Zealand 2Tonga Geological Services, Government of the Kingdom of Tonga, Tongatapu, Tonga 3Department of Geology, University of Otago, Dunedin, New Zealand 4School of Earth & Atmospheric Sciences, Faculty of Science, Queensland University of Technology, Brisbane, Australia 

  • Presentation type: Poster

  • Presentation time: Monday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 191

  • Programme No: 3.3.22

  • Theme 3 > Session 3

Abstract

We present an overview of the chronology of the explosive 15 January 2022 Hunga eruption. This 11-hour event is described in ten distinct stages. Pre-climax pumice rafts, arriving to the shore of Tongatapu in early January, are associated with Surtseyan eruptions from 29/12/21--04/01/22 (stage-1). Pumice rafts arriving post-eruption are produced during the onset of the climatic phase of January 15th, occurring shortly before 04:00 UTC (stage-2). Afterwards, two waves were witnessed at Tongatapu. Firstly a ~15--20 min period of lapilli fall (~04:40--05:00 UTC, stage-3) was recorded in phone videos on Tongatapu and Eua (65--115 km from the volcano). The 0.5--5 cm diameter, low-density particles formed a clean, sparse layer (approx. 1--2 particles/10 cm2). Next, coarse-medium ash fell (stage-4), as the island went into darkness. On the western Tongatapu coast, stage-4 fall is covered by a tsunami deposit (05:05~15) and stage-5 fall lies below the largest tsunami deposit of ~05:45 UTC. Stages-6, 7, and 8 are represented by layers (~1 cm each) of medium-sized ash particles above the largest tsunami. A final thin layer of ash fall (stage-9) is above a tsunami deposit of ~08:45--09:00 UTC. The waning activity (stage-10) is represented by surtseyan fresh bombs. Tephra deposits are pumice-dominated initially, and become generally finer, denser and less sorted over time. The dispersion axis of the fall was weakly directed towards the ESE. Particle physical characteristics suggest that apart from the initial minutes, the primary fragmentation mechanism was magma-water interaction.