5.9 5.8 (downgraded from earlier assessments) and 6km deep earthquake centered near Richmond, Virginia earlier today. It was felt in NYC and other states, and generated countless "I felt it" tweets throughout the US (as well as bad jokes and false reports of collapsing buildings). The quake is the largest on record in Virginia, an area where earthquakes are very rare in general.
Oddly, the largest quake in a century also hit Colorado last night: a 5.3, which was followed by a flurry of smaller aftershocks. Not implying they're connected to the Virginia event, but it's odd that two very rare seismic events in the US would happen within one day. My Boing Boing colleague Rob Beschizza blames the GADAFFI ACTIVATED TESLA DEATH RAY.
My family is from this area, and I grew up near here. The epicenter was in Mineral, Virginia. Also in Mineral Virginia, the North Anna Nuclear Power Station, which went offline safely and is running on generators as I type this post. Jim Sciutto of ABC News says one of the backup generators actually failed, so they are running on "backup backup."
Here is a quickie google map I threw together showing how close the epicenter was to the nuclear plant. On NBC News, Jim Norvelle of Dominion Power said the plant was designed to withstand earthquakes of magnitude 5.9 to 6.1. As noted earlier by Rob, this earthquake was initially reported as a 5.9, so… that's not too comforting.
Here's some interesting geology background on why quakes in this area are felt so far away.
The devastation in Washington, DC was immense.
Update: The NYT Lede blog reports of structural damage at the Smithsonian in DC, and other locations. Quake felt as far away as Canada.