Huge Bulge in Earth’s Crust Found

PORTLAND, Ore. — A significant bulge in the Earth’s crust has developed over the last four years near volcanoes in central Oregon, but it’s not clear whether that presages a volcanic eruption, geologists said Tuesday.

The bulge--9 to 12 miles across and about 4 inches high--was detected by satellite radar, said Willie Scott, a scientist at the U.S. Geological Survey’s volcano lab in Vancouver, Wash.

“Because it’s a volcanic area and there’s been a long history of volcanic activity in that part of the Cascades, it’s possible it might be magma, or molten rock, moving deep underground,” Scott said.

The bulge is near the Three Sisters, three volcanoes at the center of the Cascade Range in Oregon.

The last major eruption in the Pacific Northwest occurred in May 1980, when Mt. St. Helens blew off about 1,300 feet of its top.

The uplift is too broad and low to be noticed from the ground.

Scientists have looked across the West for signs of bulges, but this is the first prominent change on record using this technique.

“But there’s nothing right now that makes us think there’s an imminent danger” of an eruption, Scott said.

The Cascades, which run from California into British Columbia, have several volcanic peaks.