Earthquake shakes Blowing Rock and Boone
The U.S. Geological Survey confirmed an earthquake struck two miles north-northeast of Blowing Rock and three miles south of Boone around 3:50 p.m. Sunday.
The USGS said the quake originated at a depth of 5.7 miles, according to the agency’s Earthquake Hazards Program website.
Marshall, discussing the earthquake via an ASU Web page, said the earthquake’s depth was very shallow, which could explain the intense shaking felt on the surface.
Area residents in Boone, Vilas, Bethel, Meat Camp, Blowing Rock and other areas reported a sudden, abrupt shaking, as if a vehicle had collided with their buildings, according to comments on the Watauga Democrat Facebook page.
Others reported hearing a loud boom, followed by the shaking.
Melissa Harmon, manager of the Watauga County Communications Center, said dispatchers received about 50 to 60 calls about the earthquake, with half of the calls via 911 and half on a nonemergency line.
Harmon said most callers thought an explosion had occurred.
“Thank goodness there was no damage,” she said.
According to USGS, earthquakes occur on faults within bedrock, usually miles below the Earth’s surface. Most bedrock beneath the inland Carolinas assembled as continents collided to form a supercontinent about 500 to 300 million years ago, raising the Appalachian Mountains, it said.
In North and South Carolina and bordering areas of Georgia and Tennessee, smaller earthquakes are felt about once each year or two, while moderately damaging earthquakes hit the area every few decades.
The largest earthquake in the area on record was a magnitude 5.1 in 1916, the USGS said.
“Even though this region is not on an active plate boundary … we can still have motion within a plate,” Marshall said. “Many earthquakes in the eastern U.S. may be due to ridge push from the Mid-Atlantic Ridge, which is pushing the North American plate westward.”
And earthquakes occurring away from plate boundaries can be felt over much further distances than earthquakes originating closer to boundaries, scientists say.
Many local residents recall movement in the Boone area from the August 2011 5.8 magnitude earthquake with an epicenter in Mineral, Va., a two-hour drive southwest of Washington, D.C.
For more information, visit http://geology.appstate.edu/outreach/ask-geologist/blowing_rock_earthquake.