USGS reports preliminary magnitude of 5.8, depth= 6 km, (about 4 miles deep) on an earthquake in Central Virginia about 5 miles south of Lake Anna. I just felt the earthquake in Jacksonville, NC as a about 10 seconds of sharp but not violent shaking motion. This seemed a little higher frequency shaking than the earthquakes I felt while living in Los Angeles.
Location on google maps here
The earthquake was fairly close to the North Anna nuclear power station. I have not yet heard of any effects on the nuclear power plant.
Reuters reports that 2 reactors at North Anna shut down and went to diesel power.
http://www.reuters.com/...
Two reactors at the North Anna Station in Mineral, Virginia, tripped, the NRC said. The plants lost off-site power, but diesel generators are operating, the spokesman said.
The earthquake does not appear to have taken place on a fault that can be seen on the surface. There is a zone centered about 30 miles northwest of Richmond on I-64 called the Central Virginia seismic zone where small earthquakes have happened infrequently over reported history.
According to the USGS this is the largest earthquake in the central Virginia seismic zone in United States' history. Earthquakes have been noted infrequently here since settlers landed, but this earthquake was a full order of magnitude stronger than the previously largest event in the region.
Tectonic Summary
EARTHQUAKES IN THE CENTRAL VIRGINIA SEISMIC ZONE
Central Virginia Seismic Zone Since at least 1774, people in central Virginia have felt small earthquakes and suffered damage from infrequent larger ones. The largest damaging earthquake (magnitude 4.8) in the seismic zone occurred in 1875. Smaller earthquakes that cause little or no damage are felt each year or two.