This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: In 2022, the eruption and collapse of an underwater volcano in Tonga caused a devastating tsunami that killed four people, disrupted seafloor ecosystems and damaged critical seafloor telecommunications cables. It was one of the most powerful volcanic events this century.
All active volcanoes pose potential risks to surrounding populations, but when they are at the bottom of the sea, they present a raft of different dangers, including giant waves that can wash over distant shorelines without warning. Studying them from above the surface can also be difficult because of their extreme depth and relative inaccessibility. The 2022 eruption caused the sudden collapse of Hunga volcano's caldera, the large, bowl-shaped depression that forms when the ground above a magma reservoir sinks.
Yet how these structural failures create and intensify tsunamis is not well understood. To get some answers, a team of researchers led by Dr. Marta Ribó of Auckland University of Technology focused on the caldera's collapse.
The scientists reconstructed how the caldera collapse unfolded during the eruption. This involved comparing high-resolution sonar maps collected before the event in 2015 and 2016 with new surveys gathered throughout 2022 to measure changes in the seafloor's shape. They also used sub-bottom seismic profiling, sending sound waves into the seabed to look beneath the seafloor.
This allowed them to see hidden layers of fallen debris and volcanic material. The findings are published in the journal Nature Geoscience. The results are also discussed in a Research Briefing in the same issue.
The study found that the caldera deepened from about 150 meters (490 feet) to 850 meters (2,790 feet) below sea level. A total of 8.9 cubic kilometers (2.1 cubic miles) of seafloor material was displaced, with 6.85 cubic kilometers (1.6 cubic miles) coming directly from the caldera collapse and the rest from surface erosion. So what did all this tell the team?
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