- uploaded: Aug 23, 2011
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A strong earthquake measuring 5.9 struck the US east coast on Tuesday, rattling buildings in downtown Washington and causing evacuations of buildings as far away as New York.
The Pentagon was evacuated after the regionâ€™s rare temblor, which according to the US Geological Survey had its epicentre near Richmond, Virginia. The US Capitol Building in Washington was also evacuated.
The USGS said the quakeâ€™s centre was 34 miles from Richmond, Virginia, and 87 miles from Washington.
The quake was felt over a wide area across the US east coast, and prompted the evacuation of a number of towers and court houses in New York City.
Breaking: U.S. Geological Survey has confirmed an earthquake struck central Virginia at 1:53 p.m 4 miles south southeast of Louisa, Virginia near Mineral Va. It has been felt throughout the D.C. metro region. Initial indications are that it measured 5.9 on the Richter scale.
Minutes after the quake, the director of the U.S. Geological Survey, Marcia McNutt -- who watched objects falling from the shelves in her office -- cautioned that the shaking might not be over.
"What the concern is, of course, is that this is a foreshock. If it's a foreshock, then the worse is yet to come."
She said the energy from earthquakes on the East Coast does not attenuate as quickly as it does on the West Coast, and thus even a relatively modest tremor can shake a very broad.
"When something like this happen, everyone has to remember, more than half of the states in the U.S. are considered earthquake country. When something like this happens, remember what to do in the case of a seismic event. Duck, get under something sturdy like a desk or a doorway, get away from falling glass. Make sure that you are not in the way of falling objects like pictures, bookshelves, books, anything that's not firmly connected the wall."
An earthquake also occurred in the region July 16, 2010. A 3.6 magnitude quake centered near Gaithersburg shook the region. Today's 5.9 magnitude quake is 200 times bigger than that quake and more than 2800 tiimes as powerful (USGS How Much Bigger Calculator).
CNN is reporting Virginia has recorded only 25 earthquakes since it became a state.
The Virginia Tech Seismological Observatory(VTSO) offers the following on earthquake history in the central Virginia seismic zone:
Since at least 1774, people in central Virginia have felt small earthquakes and suffered damage from infrequent larger ones. The largest damaging earthquake (magnitude 4.8) in the seismic zone occurred in 1875. Smaller earthquakes that cause little or no damage are felt each year or two.
It would appear today's quake there is the largest on record.
VTSO adds the following:
A magnitude 4.0 eastern U.S. earthquake typically can be felt at many places as far as 100 km (60 mi) from where it occurred, and it infrequently causes damage near its source. A magnitude 5.5 eastern U.S. earthquake usually can be felt as far as 500 km (300 mi) from where it occurred, and sometimes causes damage as far away as 40 km (25 mi).
Early reports on the USGS website indicate that the quake was felt from New York City to Charlotte, N.C. and as far west as Cleveland.
From Mike Blanpied, associate coordinator for the USGS earthquakes hazards program:
"Aftershocks could go on for days, weeks, or even months. They're most likely to be felt under the next 3 or 4 days."
"The rocks are old and cold and they carry the seismic energy very far. Even a magnitude 6 or less earthquake can be felt over a considerably large area, unlike California where the shaking is more concentrated," Blanpied said.
East coast quake: Airports ground planes, office workers allowed back into buildings, no injuries or damage reported