(SARATOGA SPRINGS, NY) – Did you feel any shaking on Tuesday, August 23, 2011, a little before 2pm? It would have been for between 20 and 30 seconds. Well if you did, it was likely the magnitude 5.9 earthquake outside of Mineral, Virginia, which struck at 1:51pm and occurred 3.7 miles below the surface of the earth. The epicenter was 36 miles northwest of Richmond, Virginia, and 88 miles southwest of Washington, DC.
According to the USGS (United States Geological Survey) Theoretical P-Wave Travel Times, Saratoga Springs, NY would have felt the quake 1.5 minutes later than when the earthquake happened.
This was the largest earthquake to ever occur in central Virgina, according to records. The previous one was a magnitude 4.8 in 1875. In Washington DC, the Capitol Building, Pentagon, and all national memorials were evacuated. Two nuclear reactors were taken offline, but no damage was reported. Flights out of DC, NY, and Philadelphia were delayed. In Mineral, Virginia, itself, the town hall roof collapsed. (UPDATE 8/24) For some more detailed local and regional geology and the context of the earthquake, see this post by Callan Bentley at Northern Virginia Community College.
As you can see in the seismograph, the largest recording begins at 17:52 GMT (Greenwich Mean Time). This is the same as 1:52 pm EST (Eastern Standard). This is the P-Wave, followed by the slower S-Waves, which appear as the taller part of the recording. On this same date, August 23, 2011, the seismograph also picked up another earthquake. This other one was a magnitude 5.3, located 180 miles south of Denver, CO, which occurred at 5:46 am GMT (1:46 am EST) with a travel time of a little over 5 minutes. Here’s a link to the most recent earthquakes from the last 7 days (automatically updated.)
This isn’t the first time we have reported on Skidmore College Geoscience picking up an earthquake on their seismograph. They picked up the earthquake from Japan on March 11. See the post here.
Did you feel the earthquake? Report it to the USGS here.