Rapid Caldera Collapse of Hunga Volcano Revealed in New Study
An international research team has revealed that the 2022 climactic eruption of the Hunga volcano near Tonga caused a massive submarine caldera collapse, displacing 8.9 cubic kilometers of volcanic material. According to a study published on September 12, 2026, in Nature Geoscience and led by Auckland University of Technology marine geoscientist Dr Marta Ribó, the event deepened the caldera from 150 meters to 850 meters and exposed critical gaps in global preparedness for submarine volcanic hazards.
Quantifying the Hunga Caldera Collapse and Displaced Volume
Using high-resolution bathymetric surveys and water column observations, the research team calculated the total volume of material displaced during the eruption. According to Auckland University of Technology, the 8.9 cubic kilometers of displaced material equals the volume of 1,500 Great Pyramids or 89,000 modern aircraft carriers.
Most of this massive displacement stemmed from the rapid collapse of the caldera floor itself, while the remaining volume resulted from surface erosion driven by eruption-fed underwater currents. Despite the staggering scale of the collapse, the ejected material comprised less than 30% of the volcano’s total magma reservoir, according to findings from the international research collaboration.
Submarine Volcanic Hazards and Tsunami Generation
The extreme steepness and unprecedented speed of the caldera’s collapse on January 15, 2022, generated catastrophic volcanic-tsunamis and global atmospheric pressure waves. According to Auckland University of Technology, the resulting waves reached approximately 40 meters in height at distances up to 100 kilometers away from the source.
These fast and destructive underwater flows severed subsea communication cables and caused extensive local damage. Researchers noted that the mechanics mirror historical disasters, drawing comparisons to the 1883 eruption of Krakatau in Indonesia. That event killed more than 30,000 people through pyroclastic density currents and tsunamis, though swift action and fortunate circumstances kept the loss of life low during the Tonga event.
Urgent Need for Seafloor Mapping and Monitoring
The study highlights that pre- and post-eruption seafloor mapping of submarine volcanoes remains exceptionally rare. According to Dr Marta Ribó, at least 74 submarine volcanoes sit along the Tonga–Kermadec Arc, encompassing 20 caldera complexes that remain largely unexplored despite the severe risks they present.
Dr Ribó stated: Our findings underscore the urgent need for high-resolution repeat seafloor mapping to capture the dynamics of submarine caldera formation and collapse. These time-series datasets are essential for improving submarine volcano hazard monitoring, strengthening tsunami early-warning systems and protecting critical seafloor infrastructure, particularly in poorly surveyed regions such as the southwest Pacific.
The published research represents a joint international effort involving 22 collaborators across multiple institutions. Contributors include the Tonga Geological Services and the Ministry of Lands and Natural Resources under the Government of Tonga, alongside research bodies in New Zealand, the Republic of Korea, Australia, the United States, and the United Kingdom.