The most powerful volcanic eruption of the last century occurred in 2022 with the Hunga volcano, and new research reveals it caused massive changes to the Pacific Ocean floor, according to an international team of researchers.
In a recent paper published in Nature Geoscience, researchers revealed the extent of the underwater caldera collapse, in which material equal to 1,500 Great Pyramids was displaced, and a massive tsunami was created.
According to the team, studying this volcanic event yields important new information for monitoring such calamities and highlights what is to be gained by increased mapping efforts. Close monitoring is an essential element of tsunami early warning systems, where time is of the essence in saving lives.
2022 Hunga Volcano Eruption
Beginning December 20, 2021, and reaching its climax on January 15, 2022, the Hunga volcano eruption was a devastating underwater event. It occurred north of Tonga, an archipelago in the Pacific, and its effects spread as far as Chile, Peru, and Russia. The volcano is part of the Tonga–Kermadec Arc, a major submarine feature with 74 underwater volcanoes and 20 caldera complexes.
A caldera is a large depression that can form when magma is expelled from beneath a volcano and the overlying ground collapses. As a result of the eruption, the caldera deepened from roughly 150 meters below sea level to as much as 850 meters. The event displaced an enormous amount of volcanic material—8.9 cubic kilometers—and generated waves and underwater flows that destroyed crucial telecommunications cables and contributed to massive tsunamis. Fortunately, the eruption was far less deadly than an event like the 2011 Japanese tsunami. While millions of dollars in damage occurred, the global death toll remained at seven, despite fatalities occurring as far away as Peru.
Volcanic Caldera
While some of the displaced material resulted from erosion produced by the event, most of it was newly erupted magma. Still, only about 30% of the total magma involved was displaced, leaving a significant amount behind.
Historically, undersea volcanic calderas have been linked to some of Earth’s most catastrophic eruptions. Some 30,000 people died in 1883 when Indonesia’s Krakatau erupted, generating tsunamis and incredibly powerful ocean currents.
The Hunga caldera is extremely steep and formed during a rapid collapse, the speed and scale of which helped produce a tsunami even larger near the volcano than the one generated by Krakatau in the nineteenth century. Even about 100 kilometers from the volcano, waves reached heights of 40 meters.
Exploring the Sea
Scientists often discuss how mysterious the seafloor remains, representing a largely unexplored frontier here on our own planet. Yet with Hunga, this was not the case, as the seafloor in the region had already been extensively mapped. Having such detailed maps from before an underwater volcanic eruption is extremely rare, making this a unique opportunity for scientists to study the impact of such an event.
By comparing these before-and-after datasets, the team can identify changes to the seafloor and better understand the threats such events pose to coastal communities and critical undersea infrastructure, including communications and energy links. By collecting repeated observations, scientists may eventually be able to develop better predictive models.
The researchers say this event illustrates the need for more extensive and repeated high-resolution seafloor mapping to better study these changes. They note that the southwest Pacific is particularly in need of improved mapping. By developing better mapping datasets, the team hopes to help mitigate the impacts of future—and potentially deadlier—events.
The paper, “Rapid Submarine Caldera Collapse During the 2022 Climactic Eruption of Hunga Volcano (Tonga),” appeared in Nature Geoscience on September 11, 2026.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.