Arctic Volcanoes Found Active at Unprecedented Depths

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Ultraslow spreading ridge volcanic activity is infrequent, but the new findings of widespread rock debris suggest it could be exceptionally violent when it occurs, Sohn said.

Such violence could be the result of a build-up of carbon dioxide underneath the ocean floor.

If there was a bubble of carbon dioxide under the surface, the pressure would have built and eventually shattered through an earthquake-weakened crust, resulting in a volcanic eruption, Sohn explained.

Sohn's team suggests that the amount of carbon dioxide would need to be at least ten times more than any other documented in seafloor samples in order to produce debris scattered over such a large area.

Building a Body of Evidence

David Clague is a geologist at the Monterey Bay Aquarium Research Institute in Moss Landing, California.

"Pyroclastic eruptions have been documented along mid-ocean ridges [particularly in the Pacific], but this is the deepest site where they have been found, and also one of the larger deposits," he said.

The findings show the eruptions were from bubble-burst activity but not that they were highly explosive, said Clague, who was not involved in Sohn's study.

"The dispersal of the particles does not necessarily indicate that the eruptions were highly energetic, only that the eruption heated the surrounding seawater and the rising plume of heated water carried the lava fragments upwards where currents could disperse them," Clague said.

"The important thing is that they have extended previous findings of widespread pyroclastic eruptions on mid-ocean ridges to greater depth and much slower spreading ridges."

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