Scientists have discovered 73 previously unknown volcanoes hidden across the ocean floors.
Using an algorithm originally meant for finding impact craters on Mars, the researchers scanned the ocean floor for volcano calderas.
These are vast, multiple–mile–wide depressions in the ocean floor, formed when a powerful volcano empties out its magma chamber, causing the ground above to collapse.
Most of these sunken craters are long extinct, but several mark volcanic systems that could explode again – with potentially catastrophic consequences.
Despite producing some of the world’s most powerful eruptions, underwater volcanoes remain almost entirely mysterious, with just 30 having been documented.
If confirmed, this discovery would more than triple the number of known submarine calderas, and the algorithm may be refined to find even more in the future.
Lead author Dr Andrea Verolino, of the University of Paris Saclay, told the Daily Mail: ‘Today, the seafloor hosts an increasing amount of critical infrastructure, tens of thousands of communication cables, as well as oil and gas installations.
‘Understanding where potentially hazardous calderas are located is essential to reduce the risk of major economic disruption or, in the worst case, environmental damage if an eruption were to occur.’
Scientists have discovered 73 previously unknown volcanoes hidden across the ocean floors
Although it is much harder for scientists to observe, most of the volcanic activity on Earth actually takes place deep beneath the oceans.
Along tectonic boundaries, the plates of the Earth’s crust constantly slide past each other, collide, or pull apart, allowing magma to seep up from below.
Usually, this results in nothing more dramatic than a relatively gentle flood of magma that builds up new rock over a massive area.
However, in some cases these lava rivers pile up to create huge volcanoes that eventually erupt and collapse into calderas.
But just because a volcano has already erupted once does not mean that it is harmless.
In fact, just like the Yellowstone supervolcano caldera in the US, when an underwater caldera does erupt again, the results can be absolutely devastating.
The world received a jarring reminder of this fact in 2022 when the Hunga Tonga–Hunga Haʻapai volcano off the coast of Tonga suddenly erupted after years of silence.
The blast was the largest explosion ever recorded with modern scientific equipment, hundreds of times more powerful than the atomic bomb dropped on Hiroshima and produced shockwaves that reached space.
The researchers used an algorithm to search for volcanic calderas, large craters formed when a volcano empties its magma chamber and collapses. Pictured: A known caldera, Niuatahi, in the Tongan archipelago
Underwater caldera eruptions can be devastating, as was the case in 2022 when the Hunga Tonga–Hunga Ha’apai undersea volcano erupted with enough force to send shockwaves to the edge of space
The underwater shockwave triggered a tsunami up to 148 feet (45 metres) tall in places that caused fatalities as far away as Peru.
However, despite these risks, the vast ocean depths have made it extremely difficult to find calderas for further study.
‘Before we can assess how hazardous they might be, we need to know where they are, and until now, this knowledge was very limited in the oceans,’ says Dr Verolino.
To give volcanologists a better chance of spotting these risks before they emerge, Dr Verolino and his co–authors used an AI algorithm to search the entire seafloor.
By scanning topographical maps of the ocean, they initially flagged 87,435 possible structures.
The vast majority of these, however, turned out to be false alarms, and the researchers were able to narrow down their results to 78 possible calderas.
Of those, five had already been confirmed, which suggests that the 73 remaining possible locations have a strong chance of being volcanic craters.
These findings, published in Nature Communications Earth & Environment, also revealed where volcano calderas are most likely to be found.
Eight calderas were found on underwater mountain ranges called mid–ocean ridges, nine were found in well–known volcanic arcs, while 61 were found in the middle of tectonic plates
Eight were found on underwater mountain ranges called mid–ocean ridges, nine were found in well–known volcanic arcs, while 61 were found in the middle of tectonic plates.
Calderas often form at mid–ocean ridges where new crust is being created, before being carried away as the tectonic plates move over millions of years.
That is why more of the older calderas tend to be found in the ‘interior tectonic settings’ rather than on the active edges of plate boundaries.
Dr Verolino adds: ‘In addition, some calderas form directly within the plate itself, so–called intraplate calderas, which may be younger and potentially more hazardous than those that have drifted away from mid–ocean ridges.’
Based on this data alone, it isn’t possible to say which of these calderas are likely to erupt within a human lifetime.
However, the researchers did flag a group of seven calderas that pose the highest potential risk for future underwater investigation.
Dr Verolino says: ‘Many of the calderas we identified are probably extinct or have not erupted for thousands, or even millions, of years. For the very deep ones, we simply do not know.
‘This is why we highlighted a subset of calderas located mostly near subduction zones, where volcanic activity is more frequent and where some calderas lie in relatively shallow water, meaning any future activity could have a greater impact on human operations.’
