The detectives hunting for underwater volcanoes

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With increasingly sophisticated methods of detection, volcanologists hope to improve early warning systems, determine environmental impact, mitigate hazards posed by eruptions, and aid in ecosystem recovery. Who are the people trying to find where the next underwater volcano is hiding? And where do they look next?

Volcanos in the deep sea are much more difficult to locate than those at ground level; indeed, we know more about the surface of the Moon than we do about the ocean floor. But Hunga Tonga’s eruption has galvanised the scientific community and underscored the need for further exploration of this uncharted realm. In April 2022, New Zealand’s National Institute of Water and Atmospheric Research (Niwa) launched an ocean voyage to the site Tonga’s dramatic eruption. Their vessel, the RV Tangaroa, surveyed thousands of square kilometers of the seafloor and collected video images and physical samples, which are now being studied back on land.

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Few submarine eruptions have been documented because they are usually hidden beneath miles of ocean water. Those that scientists have observed, however, may give us clues to future disasters. In 2018, for example, an underwater eruption off France’s Mayotte Island gave rise to a colossal new seamount, revealing a high level of seismicity in the region. Mayotte is now continuously monitored, its activity regularly updated by a group of scientists on Revosima, a coordinated platform which watches over volcanic hazards such as magma flow, water temperature and acidity, as well as seismicity.

Efforts like Revosima are particularly critical for ongoing eruptions, but they are extraordinarily expensive. Ship cruise time and operations can cost up to €50,000 day (£43,500). Securing a cable near a volcanic site (which allows for local data collection) can cost millions. Infrastructure takes years to fund and establish.

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