Scientists Find Volcano Under Western Antarctic Ice Sheet

Scientists seeking the source of voluminous ice streams in western Antarctica have discovered a volcano baking under nearly a mile of solid ice near the South Pole, marking the first time an active volcano has been found under an ice sheet.

Heat from the volcano may be the source of water soaking the ground and lubricating the glaciers’ relatively rapid slide down the Whitmore Mountains, across the western Antarctic ice sheet, through the Ross Ice Shelf and, eventually, into the Pacific Ocean.

The western Antarctic ice sheet is of particular interest to scientists because it is the only ice sheet in the world that crosses ground that lies below sea level, a feature that makes it inherently unstable.

They are also interested in the effect of global warming on antarctic ice and the possibility of a catastrophic collapse of the sheet.

Such a collapse, which scientists believe is unlikely, would release enough water into the ocean to raise global sea levels by more than 18 feet, inundating many of the low-lying coastal areas where most of the planet’s population has settled.

“Catastrophe is pretty remote,” said Steven M. Hodge of the U.S. Geological Survey and a co-author of an article on the antarctic volcano to be published today in the journal Nature.

Radar mapping of the ground under glaciers showed “quite a profusion of volcanoes all over the place,” Hodge said, “but they all appeared to be dormant or extinct.”

But, he said, aerial surveys showed a distinct depression in the surface of the ice sheet, and measurements taken atop the ice showed a cone-shaped subglacial peak 3.6 miles wide and about one-third of a mile high. The heat from the volcano apparently caused the depression in the ice.

The cone sits in the middle of a deep dish nearly 14 miles wide. This dish, called a caldera, was formed when the volcano last erupted, emptying a large underground cavern of the molten rock that supported the ground above it.