Rappelling assessment of the Washington Monument on September 28, 2011.
Image: Anthony DeYoung/National Park Service
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The surprise magnitude-5.8 earthquake that stuck central Virginia and rattled cities up and down the US East Coast last year was a record-breaker in more ways than one. Not only was it felt by more Americans than any previous tremor, it triggered landslides over a wider area than any other recorded quake anywhere in the world, scientists say. A detailed analysis of ground motions triggered by the event also indicates that Washington DC and other affected population centers could be at a higher risk of major ground movement than previously recognized.
Centered roughly 130 kilometers south-southwest of the US capital, near the town of Mineral, Virginia, the 23 August 2011 quake was the strongest to strike the eastern United States since 1897, Susan Hough, a seismologist with the US Geological Survey (USGS) in Pasadena, California, reported this week at the Geological Society of America's annual meeting in Charlotte, North Carolina. The quake was felt from Florida to southeastern Canada and as far west as Wisconsin, she noted. By some estimates, as much as one-third of the US population was shaken by it.
Because of a variety of factors, including the age, type, temperature and density of the rocks underlying the eastern United States, seismic waves are transmitted more efficiently there than in the western states. The area shaken by the magnitude-5.8 quake was approximately the same size as that rocked by a much larger magnitude-7.2 tremor that struck Baja California in April 2010, Hough noted.
Quake damage
The Virginia quake was strong enough to do serious damage to some of Washington’s landmark buildings. The National Cathedral suffered about US$20 million in structural damage, including fallen statues and cracked gargoyles. At the Washington Monument, much of the damage was confined to the pyramid-shaped top of the 169-meter-tall obelisk. Analyses of seismic data gathered at an instrument near the monument suggest that accelerations due to ground motions did not exceed 0.07g. That would normally not be expected to cause damage, but Donald Wells, an engineering geologist at AMEC, a consulting firm in Oakland, California, says his team’s models suggest that passing seismic waves vibrated the tall, slim monument like a tuning fork.
Other data from the Virginia earthquake suggest that US cities on the eastern seaboard could be more affected by future earthquakes of a given size than previously thought. An unusually high fraction of the seismic energy radiating from last year’s quake was directed towards the northeast, where several major population centers lie, along the network of faults in the region, says Rufus Catchings, a seismologist with the USGS in Menlo Park, California. This preferential concentration and amplification of seismic energy has been noted in other fault-ridden regions of the world, but hadn’t been measured in the eastern United States, partly because substantial quakes are not that frequent there, he told the meeting.
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Add CommentSomeone came up with the underground nuclear war theory. Underground cities was allegedly destroyed near Washington and Colorado.
Reply | Report Abuse | Link to thishttp://www.youtube.com/watch?feature=endscreen&v=hu4GfikuJEA&NR=1
Large explosions used in coal mining and oil drilling have proven to cause earthquakes. Smart business can work cleaner and safer.
Reply | Report Abuse | Link to thisHow many quakes do we need to exceed the national debt in damages?
How many super storms?
What about leaving a few natural resources for the future generations?
What about the problem of GLOBAL debt?
Check out the global debt map, very few areas are not in debt, just like us. This is a global problem, not just about the US.
See the clean water global map and the population global map!
Where is the US in educational scores world wide?
Typical article. Worried about cracked gargoyles to deflect any unfortunate thoughts about why North Anna Nuclear Power Plant, 11 miles from the epicenter and shaking beyond its design limits, nearly drained Lake Anna, it's only source of cooling water to keep the reactors from melting down, Fukushima Style, below the intake of the cooling pumps.
Reply | Report Abuse | Link to thisThe solution? Build a THIRD new nuclear power plant to increase the load on Lake Anna's lake level WHEN, NOT IF, the fault line so near this plant, only 68 miles from Washington, DC and the gargoyles cracking, starts shaking so hard yet again.
They really don't know what the condition of the miles of piping and conduit under the plant suffered as it's buried in the ground. NRC let them go back online after the coverup and they run at 100% tonight.....
.......just waiting for another VA quake.....
That would be the Yellowstone super caldera. If it blows then roughly half of the USA and part of Canada get depopulated. I'm sure that there are dormant volcanoes where ever the plates meet. Don't hold your breath on any eruptions happening soon. Earthquakes have been happening for centuries and rarely impact volcanoes.
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