Enormous waves unleashed, yet minimal lives lost in the catastrophe.
A recent study by researchers at the University of Miami Rosenstiel School of Marine, Atmospheric, and Earth Science, in collaboration with the Khaled bin Sultan Living Oceans Foundation, has revealed that the 2022 Tongan underwater volcanic eruption surpassed the power of the largest U.S. nuclear detonation.
Emanating from Hunga Tonga-Hunga Ha’apai, the colossal 15-megaton volcanic blast—among the most significant natural explosions in over a century—triggered a massive tsunami. Waves reached heights of 45 meters (148 feet) along Tofua Island’s coast and 17 meters (56 feet) on Tongatapu, Tonga’s most populous island.
Featured in Science Advances, researchers from the Rosenstiel School conducted an analysis that combined pre-and-post satellite images, drone mapping, and on-site observations gathered by scientists at The University of Auckland. Additionally, data from the Khaled bin Sultan Living Oceans Foundation Global Reef Expedition was used to develop a tsunami simulation for the Tongan Archipelago.
The findings revealed that the region’s intricate shallow bathymetry functioned as a low-velocity wave trap, ensnaring a tsunami lasting over an hour with waves reaching up to 85 meters (279 feet) tall just a minute after the initial blast.
The undersea volcanic eruption at Hunga Tonga-Hunga Ha’apai, responsible for the formation of Tonga’s island chain due to the convergence of the Pacific and Indo-Australian tectonic plates, was comparable in scale to the devastating 1883 Krakatau eruption, which claimed more than 36,000 lives.
“Despite its size and long duration, the mega-tsumani that resulted from Hunga Tonga-Hunga Ha’apai claimed few lives,” points out Professor Sam Purkis, chair of the Department of Marine Geosciences at the Rosenstiel School. “The main factors that led to this, we suggest, are the quirk of the location, the COVID-19 pandemic, and increased evaluation drills and awareness efforts carried out in Tonga in the years prior to the eruption.”
The simulation further indicated that the positioning of the eruption in relation to populated areas contributed to preventing a more disastrous impact on Tonga.
“While 2022 may have been a lucky escape, other submarine volcanoes possess the capacity to spawn a future tsunami at the same scale,” adds Purkis.
According to the professor, the eruption offers valuable insights for understanding both historical and future tsunamis in Tonga and other regions. Serving as an exceptional natural testing ground, the eruption allows for the examination of theories and models that can be applied in different locations to enhance disaster readiness and gain a deeper understanding of analogous eruptions and subsequent tsunamis documented in ancient history and geological records.
Image Credit: © 2022 European Space Agency – ESA, produced from ESA remote sensing data, image processed by ESA. Radiometrically enhanced by CSTARS.