People crowd Market Street after evacuating buildings after 5.9 magnitude earthquake was felt in the area, Philadelphia, PA. AP photo.
UPDATE 10:31PM WASHINGTON (AP) -- The National Park Service says most of the monuments and memorials on the National Mall have reopened after being closed following the East Coast earthquake.
That excludes the Washington Monument that will be closed indefinitely after engineers found cracks near the top.
The park service says all monuments and memorials were initially evacuated and closed, including the new Martin Luther King Jr. memorial.
But the King memorial and several others that don't include large buildings were reopened within an hour of the 5.8-magnitude earthquake, which struck at 1:51 p.m. Visitors continued streaming through the King memorial Tuesday afternoon.
The Lincoln and Jefferson memorials were closed for several hours but reopened Tuesday evening. The Old Post Office tower will reopen Wednesday morning.
(USA TODAY)- A powerful earthquake rocked the Mid-Atlantic region Tuesday afternoon, hitting areas from North Carolina to as far north as Ottawa, Canada.
The earthquake, which hit at about 1:51 p.m. ET, measured 5.8 and lasted up to 45 seconds, according to the U.S. Geological Survey. It shook office buildings and homes and rattled residents. The USGS warned of aftershocks.
Its epicenter was reported about 4 miles southwest of Mineral, Va., near Richmond, Va., and about 80 miles south of Washington, D.C.
VIDEO: Live coverage from WUSA in Washington
PHOTOS: Earthquake rocks East Coast
STORY: Did you feel that? Cell networks clogged
Witnesses reported a low rumble that grew to distinct and sustained shaking, rattling windows and fraying nerves.
"It scared the heck out of me. I'm still shaking," said Joan Morris, spokeswoman for the Virginia Department of Transportation.
Although there were reports of damage to homes and commercial buildings in Mineral and surrounding Louisa County, no major injuries were reported, says Amanda Reidelbach, public information officer for Louisa County, where Mineral is located.
"We've had numerous calls of structural damage, but only one home was reported destroyed and no one was home at the time,'' Reidelbach says.
Louisa County, home to about 33,000, is a mostly rural area. "That probably worked in our favor - most of the homes are one or two stories. So are the commercial buildings,'' she says.
Federal officials say two nuclear reactors at the North Anna Power Station in Louisa County were automatically taken offline by safety systems around the time of the earthquake.
However, the plant lost offsite power and is running on four diesel generators there to power cooling systems there. Workers are trying to restore power to the site. The facility declared an "unusual event" the lowest-ranked alarm, as did nine other plants in four states, Pa., Va., Md., and N.J., which have offsite power and did not need to shut down.
Verizon Wireless, AT&T and Sprint say their networks were congested as the quake sent people scrambling for the phones. Twitter lit up with personal earthquake reports up and down the East Coast.
One Twitter user, @allisonkilkenny, a blogger and contributing reporter for The Nation, wrote: "Weirdest moment: Seeing the people I'm following in DC tweet 'earthquake' seconds before I felt it here in NYC."
Sonia Spence, a data transcriber for the U.S. Department of Citizenship and Immigration Services in Manhattan, said she had just returned to her desk on the fourth floor of 26 Federal Plaza when the building began to sway.
"I thought, 'What could be shaking the building like this?' My first thought was a terrorist," she said.
Spence, a legally blind Bronx resident, said she dropped her purse which contained her cellphone, hurrying downstairs and outside.
The earthquake was one of the largest ever recorded in the Washington, D.C., area. The depth of the quake was only 0.6 miles which partly explains the widely felt shaking.
On "the East Coast you have this old, hard, cold crust that does a lovely job of transmitting the waves ... the energy. ... This large of an eathquake could definitely have been felt hundreds of miles away," said Lucy Jones, a seismologist at the USGS. "Central Virginia does get its share of minor earthquakes, but an earthquake of this size on the East Coast is certainly very unusual," says seismologist Karen Fischer of Brown University.
Virginia is not on an active earthquake fault and is roughly in the middle of the North American continental crustal plate, she says. But it has residual fault scars left over from 200 million to 300 million years ago, when it was an earthquake zone, at the time when the Atlantic Ocean rifted apart from Europe. An earthquake that registered 3.9 hit in 2003, followed by a 4.5 that same year.
"We are just seeing pressure build up and release on those scars," Fischer says. "There is a lot of debate on exactly what is going on down there and exactly how quakes this big happen in this kind of crustal zone."
Fischer says the shallow depth of the Virginia quake is only a first estimate and will likely be revised.
"One lesson of this quake is that building codes will likely need to be revisited on the East Coast," Fischer says. "Because we are not as conscious of earthquakes here as the West Coast, and we will have to see about structural damage to buildings, although I have not heard any damage reports so far."
David Oppenheimer, a seismologist for the USGS at the Earthquake Science Center in Meno Park, Calif., said Tuesday's temblor was not expected. Oppenheimer said the quake is a big concern because the infrastructure in the region is not build to handle the shaking.
"This is the kind of thing that we worry about, infrequent large earthquakes in highly population areas with an old inventory of brick buildings, structures built before there were earthquake codes," he said. "You put this earthquake under a more urban area you would have had perhaps loss of life and more damage."
Tomas Rockwell, professor of geology at San Diego State University, said people in the region should be prepared for numerous aftershocks that could last for months.
"Earthquakes of this size typically have aftershock sequences," he said. The largest aftershock is typically one magnitude point below the main shock. So an aftershock will likely be in the high 4s or a magnitude 5, and then there will be a bunch of 4s and 3s and 2s, he said.
Tuesday's quake had officials in the region scrambling to evacuate office buildings, monuments and airports.
The control towers at John F. Kennedy and Newark Liberty airports were evacuated by the Federal Aviation Administration as a precaution, an FAA spokesman said. Flights out of both airports were canceled.
The State Department building in the Foggy Bottom area of Washington evacuated, public affairs specialist Urenia Young said in an e-mail. "We are out of the building," she wrote.
Halley Pack, a 24-year-old paralegal, was putting on her sneakers in the basement-level gym of her office building in downtown Washington when the shaking started. She said she didn't realize that it was an earthquake at first.
"I've never been in an earthquake before," she said, standing in her exercise clothes outside her office building at 2:20 p.m. "I thought something was wrong with me, like I had a headache." Pack said she even jumped on the elliptical trainer for a few minutes before officials announced that the building was being evacuated.
Outside, dozens of office workers milled about comparing notes and trying to reach friends and family on their mobile phones. The quake knocked out traffic lights, snarling traffic as fire trucks and other emergency vehicles, sirens blaring, snaked through the confusion.
Pack's colleague Caitlin Shea, 22, said she was at her desk when the earthquake struck. "The filing cabinets started shaking. I thought they would topple on us."
She was nervous about re-entering the 12-story building where they work. "I'm afraid of aftershocks," she said.
In North Carolina, the tremors sent light bulbs shaking in their fixtures and brought people out into the street looking for a potential cause. Karen Schaefer was stopped at a traffic light in northern Raleigh when her 1995 Honda Accord began shaking.
"It felt like when you are sitting on a suspension bridge and you feel it swaying," she said. "But I knew I wasn't on a suspension bridge. I was, like, 'Is this an earthquake?' and I said, 'No, this is Raleigh, N.C.'"
In the Oak Run/Ivy Ridge area near New Castle, Del., Mary Lou Byrd and Buzz Hamilton were standing outside after the quake rumbled.
"I was just standing in my house, and it started shaking," Byrd said. "I wasn't sure it was an earthquake until I saw all of the neighbors standing in the street talking to each other."
"I thought someone was barreling up the road with a trash truck, but the whole house shook, and we heard dishes rattling," said Shaun Gallagher of the Forest Brook Glen development near Newport, Del.
"It felt and sounded like a big gust of wind came through. I looked outside and the trees weren't even moving," said Jean Carsten, 59, who was at home in Bayville, N.J., when she felt the tremors. "My husband said, 'That was an earthquake.'"
Dan Thompson, director of communications at Fork Union Military Academy, a military-style boarding school in the village of Fork Union, Va., said the shaking was "pretty significant, but there was no damage or injuries. Just a few books knocked off the shelves."
About 200 were on campus either as members of the football or soccer teams, or as part of the 60 cadet officers here for training. "We want all our parents to know everyone is safe, and there's no danger at this point," Thompson said.
"No need for any of that. Everything's in good shape," he said, then offering a quip about another natural event, Hurricane Irene, bearing down on the East Coast: "We're already looking forward to the hurricane."
Locally here in West Michigan residents say they felt tremors. Jeff and Sharon Jones felt their home shake. They say jokingly they thought it was 'old age acting up.'
Jeff Jones says, "I felt kind of a jolt-- I thought maybe it was my old body acting up. When you get old little things happen."
Eventually he realized his wife also felt the tremors.
Workers at Metro Health say they could also feel shaking on the fourth floor.