Earthquake in Central Virginia

Origin Time: December 9, 2003, 20:59:14 UTC (3:59 p.m. EST)
Location: 37.599º N   -77.932º W
Magnitude: 4.5 mbLg
Depth: less than 5 km

A moderate earthquake struck central Virginia on December 9, 2003. Although the 4.5-magnitude event caused little damage, it was felt throughout a wide area of Virginia and adjacent states. There were a few reports from as far away as Marietta, Ohio. More than 14,000 felt reports were received by the U.S. Geological Survey. Maximum Modified Mercalli Intensity was VI. This earthquake was unusual because it was a double event; that is, two earthquakes of nearly equal size occurred about 12 seconds apart. Seismograms from this event typically exhibit two P waves and two S waves http://www.geol.vt.edu/outreach/vtso/. The earthquake was recorded by Ohio Seismic Network stations throughout the state.

Seismogram of the central Virginia earthquake recorded at Ohio Seismic Network station ACSO at Alum Creek State Park, at a distance of 324 miles (522 kilometers) from the epicenter. Note the two sets of S waves, indicating two events, about 12 seconds apart.