A Nature Geoscience study found Hunga’s seafloor crater plunged from 150 meters to 850 meters below sea level during the January 15, 2022 eruption.
Bathymetric surveys and water-column data showed 8.9 cubic kilometers of material were displaced, mostly by rapid caldera collapse rather than surface erosion from eruption-fed currents.
That collapse helped drive marine hazards from the blast, including underwater flows that damaged subsea telecom cables and tsunami waves about 40 meters high up to 100 kilometers from the volcano.
Researchers said the displaced material was still less than 30% of Hunga’s magma reservoir, offering rare detail on how major submarine calderas fail during explosive eruptions.
The team said the findings expose a preparedness gap for submarine volcanoes—especially along the Tonga-Kermadec Arc—and strengthen the case for repeat seafloor mapping and better tsunami warning systems.
Why did an eruption emptying less than a third of its magma reservoir cause one of this century's most violent caldera collapses?
Could the hidden weakness of unmapped submarine volcanoes suddenly trigger devastating tsunamis and sever global communications without warning?
Hunga Tonga 2022: How a Single Eruption Reshaped Methane Chemistry, Tsunami Science, and Climate Understanding
Overview
The January 2022 Hunga Tonga-Hunga Ha’apai eruption blasted massive amounts of salty ocean water and ash high into the stratosphere, where sunlight triggered chemical reactions that produced reactive chlorine atoms. These atoms rapidly destroyed methane, a potent greenhouse gas, as proven by tracking formaldehyde in the volcanic plume for ten days. This natural methane destruction sparked debate about using similar chemistry for climate intervention. The eruption also destabilized the volcano’s magma chamber, causing a dramatic caldera collapse and underwater landslides. Additionally, the eruption generated a powerful atmospheric wave that triggered a meteotsunami, exposing weaknesses in early warning systems and prompting regional efforts to improve disaster preparedness.