ROANOKE, Va. – You may remember where you were and what you felt on August 23, 2011.
Early in the afternoon, the ground began to shake from what the USGS calls “America’s Most Widely Felt Earthquake.”
Why? There were nearly 150,000 reports of shaking, from Florida to eastern Canada and west to the Mississippi River Valley. This wide radius of shaking has to do with how much older the rock in the Eastern U.S. is as opposed to the Western U.S.
The epicenter was in Louisa County (south of Mineral) and the magnitude was 5.8 on the Richter Scale.
Luckily, no one was killed by the earthquake, but it did cause $200-300 million in damage. Notable structures that were damaged include the Washington Monument and the Washington National Cathedral.
The USGS reports there were around 4,000 aftershocks in the wake of the Louisa County earthquake.
They’ve learned that the Appalachian Mountains enhanced the shaking northeast of the epicenter. A similar pattern was observed in August 2020 during the Sparta, NC earthquake.
This was the first earthquake with a magnitude of 5 or higher in Virginia since 1897.
Fun fact: That 1897 earthquake happened in our viewing area! It was slightly weaker, a 5.6 magnitude, and the epicenter was in Giles County (near Pearisburg).
The map below shows all earthquakes in Virginia since 1812. You see that they’re not all that rare in the Commonwealth!
The 5 magnitude threshold is important because that’s when we really start to feel earthquakes and see damage from them.
The highest magnitude earthquake ever recorded in the Eastern U.S. was in Charleston in August 1886. That one reached 7 on the Richter Scale and killed more than 100 people.
Below, you’ll see where the Mineral and Pearisburg quakes fell on the Richter Scale.
Do you have an earthquake plan for your family? If not, it may be a good idea to take part in an upcoming earthquake drill.