Diverse tsunamigenesis triggered by the Hunga Tonga-Hunga Ha’apai eruption

• Published in: Nature (London) Vol. 609; no. 7928; pp. 728 - 733
• Main Authors: Lynett, Patrick, McCann, Maile, Zhou, Zili, Renteria, Willington, Borrero, Jose, Greer, Dougal, Fa’anunu, Ofa, Bosserelle, Cyprien, Jaffe, Bruce, La Selle, SeanPaul, Ritchie, Andrew, Snyder, Alexander, Nasr, Brandon, Bott, Jacqueline, Graehl, Nicholas, Synolakis, Costas, Ebrahimi, Behzad, Cinar, Gizem Ezgi
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.09.2022; Nature Publishing Group
• Subjects: 639/766/189; 704/4111; Blanketing; Coastal hazards; Coasts; Coupling; Docks; Explosions; Far fields; Floods; Harbors; Humanities and Social Sciences; Infrastructure; Instrumentation; Land area; multidisciplinary; Science; Science (multidisciplinary); Sea level; Sea level rise; Shock waves; Tsunamis; Underwater; Underwater explosions; Volcanic eruption effects; Volcanic eruptions; Volcanoes; New Zealand; United States > US; Krakatau; Tonga
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-022-05170-6

On the evening of 15 January 2022, the Hunga Tonga-Hunga Ha’apai volcano 1 unleashed a violent underwater eruption, blanketing the surrounding land masses in ash and debris 2 , 3 . The eruption generated tsunamis observed around the world. An event of this type last occurred in 1883 during the eruption of Krakatau 4 , and thus we have the first observations of a tsunami from a large emergent volcanic eruption captured with modern instrumentation. Here we show that the explosive eruption generated waves through multiple mechanisms, including: (1) air–sea coupling with the initial and powerful shock wave radiating out from the explosion in the immediate vicinity of the eruption; (2) collapse of the water cavity created by the underwater explosion; and (3) air–sea coupling with the air-pressure pulse that circled the Earth several times, leading to a global tsunami. In the near field, tsunami impacts are strongly controlled by the water-cavity source whereas the far-field tsunami, which was unusually persistent, can be largely described by the air-pressure pulse mechanism. Catastrophic damage in some harbours in the far field was averted by just tens of centimetres, implying that a modest sea level rise combined with a future, similar event would lead to a step-function increase in impacts on infrastructure. Piecing together the complexity of this event has broad implications for coastal hazards in similar geophysical settings, suggesting a currently neglected source of global tsunamis. January 2022 saw the first observations of a tsunami resulting from a large emergent volcanic eruption (Hunga Tonga) captured using modern instrumentation, with broad implications for hazard management in similar geophysical settings.