An 'Extinct' Volcano is Waking Up in Maryland

University of Maryland researchers say thought-to-be-extinct volcano Sugarloaf Mountain, which lies 32 miles north of Washington DC, is actually still alive and active.

While this sounds like cause for alarm, the Frederick, Maryland volcano may not erupt for another 100 to 500 years. The scientists say the pending eruption could be on the same scale as the 1980 Mount St. Helens volcanic explosion.

According to the team from UMD’s Department of Geology, the volcano was believed extinct because its last eruption took place 22,000 years ago. Now, after a series of earthquakes in the 2000s and the formation of a steam vent and tar pit, the team says Sugarloaf Mountain is inflating. The surrounding area is rising about 14 inches annually, from magma pooling beneath the volcano.

Team seismologists recorded 286 microearthquakes of magnitude 2.0 or less over an 18-month period. Quakes that small typically are not commonly felt by people. The seismic activity created a steam vent on the northeast slope of the mountain, its plume visible for miles. The tar pit emerged on farmland at the foot of the slope and was fenced off to prevent injuries to livestock.

The last volcano to erupt in the mid-Atlantic was Trimble Knob in Highland County, Virginia. The 1832 high-speed blast leveled a half million trees and fed a towering plume of ash for 36 hours. Easterly winds carried the ash from Washington, DC to Richmond. Nine hundred people were killed, making the eruption the eighteenth deadliest volcanic event in Virginia history.

Sugarloaf's recent activity stems from a fracture that split apart beneath the volcano about 200 years ago, allowing magma to rise. The scientists estimate Sugarloaf is on a 20,000-year eruption cycle. "It's been 22,000 years since the last eruption – it's definitely due to happen in about 100 to 500 years," the scientists conclude.

The new findings were published in the journal American Geophysical Investigations.