Deep-sea volcanoes not only produce lava flows, but they also explode!

Researchers at McGill University have discovered high concentrations of CO2 at mid-ocean ridges, confirming the explosive nature of certain volcanic eruptions.

By using an ion microprobe, Christoph Helo, student in McGill's Department of Earth and Planetary Sciences, has discovered very high concentrations of CO2 in droplets of magma trapped within crystals recovered from volcanic ash deposits on Axial Volcano on the Juan de Fuca Ridge, off the coast of Oregon.

These entrapped droplets represent the state of the magma prior to eruption. As a result, Helo and fellow researchers from McGill, the Monterey Bay Aquarium Research Institute, and the Woods Hole Oceanographic Institution, have been able to prove that explosive eruptions can indeed occur in deep-sea volcanoes.

Their work also shows that the release of CO2 from the deeper mantle to the Earth's atmosphere, at least in certain parts of mid-ocean ridges, is much higher than had previously been imagined.