Surprise: Explosive volcanic eruption under the Arctic ice found

Surprise: Explosive volcanic eruption under the Arctic ice found
25
06
2008

I posted on a similar story about volcanic eruptions under Antarctic ice earlier this year. What is unique about this situation is that it was a large eruption that went completely undetected, and under pressures that they thought not possible. The big question is then; where did the heat from the volcano go, and what effect did it have on the sea ice environment? Research has been going on looking at volcanism in the ridge but this discovery of a significant eruption in 1999 is new and unexpected.

From Science and The Sea: “In the last few years, for example, scientists have found that a long ridge beneath the north polar ice cap is dotted with volcanoes, and with vents of superheated water that could be home to many new species.”

More info on the Gakkel Ridge here

Today’s Press release from EurekAlert:

International expedition discovers gigantic volcanic eruption in the Arctic Ocean




A “lonely ” seismometer drifts with the sea ice.

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An international team of researchers was able to provideevidencef explosive volcanism in the deeps of the ice-covered Arctic Ocean for the first time. Researchers from an expedition to the Gakkel Ridge, led by the American Woods Hole Oceanographic Institution (WHOI), report in the current issue of the journal Nature that they discovered, with a specially developed camera, extensive layers of volcanic ash on the seafloor, which indicates a gigantic volcanic eruption.

“Explosive volcanic eruptions on land are nothing unusual and pose a great threat for whole areas,” explains Dr Vera Schlindwein of the Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association. She participated in the expedition as a geophysicist and has been, together with her team, examining the earthquake activity of the Arctic Ocean for many years. “The Vesuvius erupted in 79 AD and buried thriving Pompeii under a layer of ash and pumice. Far away in the Arctic Ocean, at 85° N 85° E, a similarly violent volcanic eruption happened almost undetected in 1999 – in this case, however, under a water layer of 4,000 m thickness.” So far, researchers have assumed that explosive volcanism cannot happen in water depths exceeding 3 kilometres because of high ambient pressure. “These are the first pyroclastic deposits we’ve ever found in such deep water, at oppressive pressures that inhibit the formation of steam, and many people thought this was not possible,” says Robert Reves-Sohn, staff member of the WHOI and lead scientist of the expedition carried out on the Swedish icebreaker Oden in 2007.

A major part of Earth’s volcanism happens at the so-called mid-ocean ridges and, therefore, completely undetected on the seafloor. There, the continental plates drift apart; liquid magma intrudes into the gap and constantly forms new seafloor through countless volcanic eruptions. Accompanied by smaller earthquakes, which go unregistered on land, lava flows onto the seafloor. These unspectacular eruptions usually last for only a few days or weeks.

The installation of a seismometer on an ice floe.

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Volcanic ashes on the sea bed of Gakkel Ridge (Photo: WHOI)

Bathymetric chart of the Gakkel Ridge at 85°E. Photographic bottom surveys were conducted along profiles shown as thin, black lines. The photo showing volcanic ashes on the sea bed were taken at the site, which is marked with a red star and the letter a.