Earthquake in Maryland felt across area

A 3.6 magnitude earthquake rattled the Washington area early Friday, with thousands of residents reporting that they felt the ground shake as they slept or were waking. The U.S. Geological Survey said the quake was centered in Montgomery County and struck at 5:04 a.m.

“The whole house shook,” said Carroll Ripley, of Germantown. “I thought maybe there was an explosion or a plane flew over the house or something.” “I went straight outside to do a perimeter check — in my underwear,” he said. The epicenter was in the Germantown-Gaithersburg area near I-270 and Route 119 (39.167°N, 77.252°W), according to USGS. It was 3.1 miles deep. Authorities across the region said there were no reports of damage. Buses and trains ran on schedule during the morning commute, and traffic moved at its usual pace. Crews in Washington were inspecting underground facilities, vaults, tunnels, bridges and overpasses, according to D.C. Fire and Emergency Medical Services.  A natural gas leak at a maintenance depot in the Gaithersburg-Rockville area may be linked to the quake, but officials were unsure of the cause.  ”There’s not a single tree branch down,” Montgomery County Fire and Rescue Assistant Chief Scott Graham said. “This was a non-event, thank God.”

Still, many residents were dialing 911 to report the rumbling.  At Montgomery County’s emergency center, as many as 100 confused people called in during or just after the earthquake. “We were inundated with calls from people not knowing what it was,” said Gloria Jackson, a communications supervisor at the center. Amy Vaughan, a geophysicist with the USGS, said the quake was the largest recorded within about 45 miles of Germantown since a database was created to track such activity in 1974. The largest earthquake before Friday morning’s was a 2.7 tremor in 1993, Vaughan said. There was a 2.6 magnitude tremor in 1990 and quakes measuring 2.5 in 1997, 1993 and 1974. “It’s not something that’s completely out of the ordinary,” Vaughan said.At the same time, quakes measuring above 3 are extremely rare in this area. Vaughan said the number of people reporting the quake to the USGS highlighted how unusual it seemed to residents of the mid-Atlantic states. Within about two hours of the quake, more than 6,700 people had reported it on the agency’s Web site. Most were from the District, Maryland, Virginia and Delaware but reports came from far as away as New York and Georgia. Many found it thrilling.  ”It felt like the earth was churning,” said Linda Wheeler, of Monrovia in Frederick County. “I knew it was an earthquake right away because it was unlike anything I’ve ever experienced. It was actually kinda cool.” David Hayes, of Boyds, was getting dressed when he said he heard a loud rumbling. “I opened my front door and yelled ‘earthquake’ toward my neighbor. Great way to start the day!” he said. The first question journalists asked President Obama Friday morning, when he appeared outside the White House to discuss the Gulf of Mexico oil spill, was whether he felt the earthquake at 1600 Pennsylvania Avenue NW.  No, the leader of the free world answered with a slight smile, “I did not.”

Geologists note that earthquakes can occur anytime and anywhere. They are a natural phenomenon resulting from the movements of continental plates along faults under the Earth’s surface. “These faults just naturally exist and over time they build up pressure,” Vaughan said. When the pressure is released at a high enough intensity, an earthquake results. The earliest recorded earthquake in Maryland occurred in Annapolis on April 24, 1758 and lasted a full 30 seconds, according to a history posted on the USGS Web site. There have been other tremors reported periodically in the region through the years. None caused any significant damage, according to the Web site.The confusion following Friday’s quake led to some misplaced theories on its cause. Dean Miletich of Frederick said he was taking out the trash when the rumbling started. “When I came back into the garage, everything on the shelves was shaking,” he said. “It sounded like a deep rumble. When I came back inside, my wife had woken up and asked me, ‘What did you do?’”