Minutes ago, our 17-story building swayed side to side for a few seconds. Why? A 5.8 magnitude earthquake centered in Virginia, according to the U.S. Geological Survey, has shook the entire East Coast with reports on Twitter of shaking from at least Connecticut to North Carolina and inland as far as Ohio. You can get the latest information here at USGS.
As a precaution, building management is evacuating us (which is the wrong thing to do in an earthquake) and cars have started backing out of the nearby Holland Tunnel. More updates soon.
Update #1: The earthquake appears to have strengthened during the evacuation, now up to 5.9, according to USGS and centered northwest of Richmond and east of Charlottesville. Small earthquakes have been known in the region "since at least 1774," according to USGS, with infrequent larger ones. The earthquake was centered roughly one kilometer deep and, unlike earthquakes on the West Coast, such eastern seaboard quakes tend to travel far, as much as 500 kilometers. That was certainly the case here, with reports of light shaking as far away as Cincinnati and Cleveland.
Update #2: This earthquake was a low probability event (see graph below). Also, we can thank the old, hard, cold crust for the long propagation of this relatively minor quake's waves. Oh, and USGS has gone back to 5.8 and deepened the earthquake to some 6 kilometers beneath the surface (which is still relatively shallow).