PHOTOS: East Coast Earthquake Sends Strong Warning Messages
Office workers evacuated from buildings near Foley Square stand outside in New York Reuters

Tuesday's earthquake in Virginia, the largest to hit the East Coast in 67 years, made the United States question the safety of its nuclear power plants.

The earthquake, a 5.8 on the Richter scale, had an epicenter only a few miles from the North Anna nuclear power plant. The plant shut down automatically, as it was supposed to, averting a nuclear accident like the one that befell Japan's Fukushima plant March 11.

A spokesman for Noth Anna's operator. Dominion Resources, said there was no major damage to the power plant and that three diesel generators kept the reactor cool. A fourth diesel unit failed to work.

Nuclear power plants lose a significant margin of safety when they're forced to rely on these emergency backup systems, Paul Gunter, director of reactor oversight at the anti-nuclear group Beyond Nuclear, told Reuters.

The U.S. Nuclear Regulatory Commission said North Anna's shutdown was a success and that the plant was no threat to the public.

New York's emergency alert system told residents at 2:12 p.m. Eastern that This is an ACTUAL EARTHQUAKE ALERT. Many buildings in Washington, D.C., were evacuated, and two corridors at the Pentagon were flooded when a pipe broke.