The most explosive eruption of the last century – the
2022 Hunga volcano near Tonga in the Pacific Ocean –
caused massive changes to the ocean floor, displacing
volcanic material equivalent to 1,500 Great
Pyramids.
An international research team, led by
marine geoscientist Dr Marta Ribó from the Auckland
University of Technology (AUT), has just published a paper
in Nature Geoscience which demonstrates the impact of the
rapid submarine caldera collapse, and could help improve
monitoring and early-warning systems for
volcanic-tsunamis.
The 2022 Hunga eruption triggered
deadly volcanic-tsunamis, global atmospheric pressure waves
and delivered huge volumes of volcanic material into the
ocean creating fast and destructive underwater flows which
caused extensive damage to the subsea communication
cables.
Using high-resolution bathymetric surveys and
water column observations, the research team quantified the
geomorphologic changes and calculated the total volume of
material displaced during the eruption.
Dr Ribó says:
“There are at least 74 submarine volcanoes along the
Tonga–Kermadec Arc, with 20 caldera complexes. Yet,
despite the hazards they pose, they are not well-understood
as they remain unexplored. “
The team’s findings
revealed the Hunga caldera has deepened from 150m to 850m,
and that the total displaced volume of volcanic material was
8.9 cubic kilometres (equivalent to the volume of 1,500
Great Pyramids or 89,000 modern aircraft
carriers).
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Most of this material was displaced due to
the collapse of the caldera, with the rest being surface
erosion caused by eruption-fed currents. Despite the massive
displacement, the material comprised less than 30% of the
magma reservoir.
These types of submerged and
volcanic-island calderas are associated with some of the
largest and deadliest eruptions on Earth, including the 1883
eruption of Krakatau, Indonesia, which killed more than
30,000 people and caused widespread devastation due to
resultant pyroclastic density currents and
tsunamis.
Due to the steepness of the caldera and the
speed of the caldera collapse, the 15 January 2022 Hunga
volcano eruption produced an even larger tsunami than
Krakatau, with waves about 40 m high at distances up to 100
km away from the source. Despite local devastation,
fortunately few lives were lost.
Dr Ribó says:
“Seafloor mapping before and after submarine volcanoes
eruptions is very rare. Despite their recognised threat,
most submarine caldera volcanoes remain unmapped. The
bathymetric time-series of Hunga, before and after the 2022
eruption allowed us to better understand processes governing
submarine caldera formation, caldera collapse dynamics and
associated hazards such as tsunamis or dense underwater
flows.”
The 2022 eruption event exposed a critical
gap in global preparedness for submarine volcanic
hazards.
“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 Nature paper was led by
AUT’s Dr Ribó in association with 22 collaborators across
different research institutions, with joint efforts from
Tonga (Tonga Geological Services, Ministry of Lands and
Natural Resources, Government of Tonga), New Zealand
(University of Auckland, Earth Sciences New Zealand,
University of Otago), Republic of Korea (Korea Polar
Research Institute), Australia (Echoview), the US (NASA),
and the UK (National Oceanography Centre).
Read the
paper here: https://www.nature.com/articles/s41561-026-02099-7
Marta
Ribó | Mōku | About | Auckland University of
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