Scientists have identified 73 previously unknown volcanoes on the ocean floor, more than doubling the number of documented submarine calderas. The discovery, made using an artificial intelligence algorithm designed to find impact craters on Mars, highlights the vastness of unexplored volcanic activity beneath the waves.
These newly identified features are volcanic calderas—large, multiple-mile-wide depressions formed when a volcano's magma chamber empties and the overlying ground collapses. While many of these formations are likely extinct, researchers caution that several could represent active volcanic systems capable of future eruptions.
"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," said lead author Dr. Andrea Verolino of the University of Paris Saclay. The ocean floor is increasingly populated with critical infrastructure, including tens of thousands of communication cables and oil and gas installations, making the location of these features a significant concern.
Most of Earth's volcanic activity occurs deep beneath the oceans. This activity is largely driven by the movement of tectonic plates, where magma seeps up from below. Typically, this results in lava flows that create new rock, but sometimes large volcanoes form, eventually erupting and collapsing into calderas.
The 2022 eruption of the Hunga Tonga–Hunga Haʻapai volcano serves as a stark reminder of the power of underwater eruptions. The blast was the largest ever recorded by modern equipment, producing shockwaves that reached space and triggering a tsunami that caused fatalities as far away as Peru.
Finding and studying these underwater calderas has been challenging due to the ocean depths. The AI algorithm, applied to topographical maps of the seafloor, initially flagged over 87,000 potential structures. After filtering out false positives, researchers identified 78 possible calderas, of which five were already known. This suggests the remaining 73 are highly likely to be volcanic craters.
The findings, published in Nature Communications Earth & Environment, also indicate common locations for these features. Eight calderas were found on mid-ocean ridges, nine in volcanic arcs, and 61 in the interior of tectonic plates. Calderas formed within plates, known as intraplate calderas, may be younger and potentially more hazardous than those that have drifted away from plate boundaries.
While it is not possible to predict when these calderas might erupt, researchers highlighted a subset of seven that pose the highest potential risk for future investigation. These are located near subduction zones, areas of frequent volcanic activity, and some are in relatively shallow water, increasing the potential impact of any future eruptions on human operations. Predicting volcanic eruptions remains complex, with indicators such as seismic activity, gas emissions, infrasound, and ground deformation offering clues but no definitive forecasts.