An earthquake in Virginia? It's happened before.






Compiled from various sources. Historic earthquake information is from the U.S. Geological Survey.

Tuesday has been a day of rolling and tumbling on the East Coast.

A magnitude 5.8 earthquake struck near Mineral, Virginia at 1:51 p.m., with its effects felt as far away as Maine and North Carolina. Buildings were evacuated in New York and Washington, D.C., and national monuments in the nation's capital were closed for the day.

Damage appears to be light, although the central tower of the National Cathedral suffered the loss of three pinnacles on its central tower.

TMineral, Virginia is a town about an hour northwest of Richmond, within the Central Virginia seismic zone, an area crisscrossed with small faults that are a vestige of the formation of the Appalachian Mountains some 400 million years ago.

Though major earthquakes are rare on the East Coast, they are not unheard of, and minor quakes occur in Virginia every few years (in fact, earthquakes can and do occur in every state; of course, few of these earthquakes are powerful enough to be noticed). The U.S. Geological Survey lists no less than eleven earthquakes or earthquake clusters in Virginia since 1774.  A relatively large earthquake in 1875, which measured 4.9 on the Richter scale, also originated from the Central Virginia seismic zone.  Richmond suffered minor damage in that quake, and boats that had been moored on the James River were set adrift by waves kicked up by the undulating earth.

The largest earthquake in Virginia history, at least until now, struck on May 31, 1897 in Giles County, along the border with West Virginia.  That quake could be felt as far north as Pennsylvania and as far west as Indiana, and registered 5.9 on the Richter scale and VIII on the modified Mercalli scale.

(The Mercalli scale measures the destructiveness of an earthquake, as opposed to the Richter scale, which measures the energy of an earthquake. A modified Mercalli VIII earthquake will potentially cause the partial destruction of ordinary building and the total destruction of standing objects like chimneys and factory stacks. The Giles County quake certainly did both.)

Interestingly, southeastern Colorado was struck by that state's largest quake since 1882 last night. Geological experts say the Colorado and East Coast quakes are completely unrelated.


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