Hidden Explosions beneath 2 kilometers of water

1 June 2026

For decades, volcanologists have assumed that most of the world's several hundred thousand submarine volcanoes erupt quietly on the deep seafloor. At water depths of several hundred metres and more, the immense hydrostatic pressure was thought to suppress explosive activity, leading predominantly to effusive lava eruptions. This view is supported by countless seafloor surveys showing that most submarine volcanoes lack the large craters typically associated with explosive eruptions.

A new study led by marine geophysicists from the University of Hamburg and published in Scientific Reports challenges this long-standing paradigm. Investigating volcanic structures on the Azores Plateau in the central Atlantic, the researchers found evidence that several deep-water volcanoes formed through highly explosive eruptions at water depths exceeding 2,000 metres. These eruptions excavated large craters on the seafloor. However, during the final stages of volcanic activity, eruptive behaviour changed: lava flows gradually filled and concealed the craters, effectively masking the volcanoes’ explosive origins. As a result, volcanoes that appear harmless and effusive today may actually preserve a hidden record of violent explosive eruptions.

The findings suggest that explosive volcanism in the deep ocean may be significantly more widespread than previously recognized. If confirmed elsewhere, this would require a reassessment of how submarine volcanoes release magmatic gases and particles into the ocean and potentially the atmosphere, with implications ranging from marine ecosystems to regional and even global environmental processes.

The manuscript can be accessed here: