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Submarine caldera collapse during the 2022 Hunga-Tonga eruption highlighted by seismic T-waves

Bastian Steinke1, Shane J. Cronin1, Emile Okal2, Rennie Vaiomounga3, Mafoa Penisoni3, Daisuke Suetsugu4

  • Affiliations: 1School of Environment, Waipapa Taumata Rau | The University of Auckland, Auckland, New Zealand 2Department of Earth and Planetary Sciences, Northwestern University, Evanston, IL, USA 3Geology Unit, Natural Resources Division, Ministry of Lands and Natural Resources, Nuku'alofa, Tonga 4Japan Agency for Marine-Earth Science and Technology, Yokosuka, Kanagawa, Japan

  • Presentation type: Poster

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

  • Poster Board Number: 109

  • Programme No: 2.1.19

  • Theme 2 > Session 1

Abstract

Submarine volcanic eruptions are a known source of destructive near-field tsunami. The 2022 Hunga-Tonga eruption produced waves with run-up heights of almost 20 metres at islands over 60 km distant, although the exact wave generation mechanism has so far remained elusive. To better understand and define tsunami genesis, this study focussed on the hydro-acoustic records of stations across the SE Pacific. Seismic tertiary waves (T-waves) result from on-land conversion of hydro-acoustic into seismic energy, which makes them an insightful proxy for underwater processes. We observed a sequence of such T-waves, which can be traced back to a coherent source near the volcano. This event coincided with a significant drop of the eruption plume and the origin time of the tallest tsunami to hit the island of Tongatapu (Kingdom of Tonga), which were both attributed to a caldera-collapse at the volcano. Hydro-acoustic emissions, which travel faster than tsunami waves, and associated T-waves from this event may therefore not only serve as a proxy for a violent and tsunamigenic process occurring at the volcano, but also as a tool to provide some warning time ahead of the incoming tsunami waves.