PARIS: Recent massive volcanoes have risen from the ocean floor deep under the Arctic ice cap, spewing plumes of fragmented magma into the sea, scientists who filmed the aftermath reported on Wednesday. The eruptions as big as the one that buried Pompei took place in 1999 along the Gakkel Ridge, an underwater mountain chain snaking 1,800 kilometres from the northern tip of Greenland to Siberia.

Scientists suspected even at the time that a simultaneous series of earthquakes were linked to these volcanic spasms.

But when a team led of scientists led by Robert Sohn of the Woods Hole Oceanographic Institution in Massachusetts finally got a first-ever glimpse of the ocean floor 4,000 meters beneath the Arctic pack ice, they were astonished.

What they saw was unmistakable evidence of explosive eruptions rather than the gradual secretion of lava bubbling up from Earth’s mantle onto the ocean floor.

Previous research had concluded that this kind of so-called pyroclastic eruption could not happen at such depths due to the crushing pressure of the water.

“On land, explosive volcanic eruptions are nothing exceptional, although they present a major threat,” said Vera Schlindwein, a geologist with Germany’s Alfred Wegener Institute for Sea and Polar Research, which took part in the study.

But the new findings, published in Nature, showed that “large-scale pyroclastic activity is possible along even the deepest portions of the global mid-ocean ridge volcanic system”.

—AFP