The earthquake on the East Coast started a debate: The tremors took experts by surprise.

Suddenly the warning lights blinked. Both reactors turned themselves off, [and] the emergency generators started up as prescribed in the emergency plan. Since Tuesday, the North Anna nuclear power plant in Virginia, is no longer online. An earthquake measuring 5.8 on the Richter scale had triggered the alert. North Anna is located only 20 kilometers away from the epicenter, the small town of Mineral, which is otherwise only a talking point in connection with country music and bluegrass festivals. The danger of a core meltdown never existed, assures a spokesman from the operator, Dominion Resources.

On Tuesday at 1:51 p.m. local time, the earth shook in the northeastern U.S. — just under half a minute of vibrating floors and walls. People were not injured. At the National Cathedral — the most well-known church in the capital — some of the tops of the decorative spires broke off. The Washington Monument, the slender-as-an-arrow obelisk with its observation deck, is closed to visitors indefinitely after structural engineers found cracks in the upper part. Most schools in the city were closed on Wednesday. A number of public offices remained closed. The last quake of this magnitude in the area was in 1897.

“We Don’t Completely Understand”

The epicenter does not lie on a fault line between two plates. “What stresses are causing these infrequent but annoying earthquakes such as the one we just felt are not entirely understood,” said Marcia K. McNutt, director of the U.S. Geological Survey. Probably “old faults from long-ago geologic eras” are activated, perhaps from the time when the Appalachian Mountains came into being. As a result of the unanticipated earthquake, the nuclear power debate has gained momentum. When the Dominion firm applied for a license to build a third reactor in 2007, it referred to studies which indicate that quakes stronger than 5.5 in Virginia are only conceivable, at most, every 10,000 years. Critics are now questioning that.

In Peekskill on the Hudson River, where the Indian Point nuclear power plant produces energy not 70 kilometers away from The New York Times, Paul Gallay from the environmental organization Riverkeeper feels his skepticism strengthened: "How many warnings do we need?" Only three years ago, scientists from Columbia University corrected their seismological prognosis for the Hudson Valley. If the earth quakes in Peekskill, magnitudes up to 7.0 on the Richter scale could be reached. In the meantime, the reactors at Indian Point were declared safe by officials because they can withstand earthquakes with a magnitude of 6.1.