REGIONAL – At 1:51 p.m. Tuesday, an earthquake measuring 5.8 on the Richter Scale shook the ground and buildings over a wide area of the East Coast, including the Hudson Valley.

The quake epicenter lay between the towns of Mineral and Louisa, in Virginia, about 84 miles south west of Washington DC. The area is known to geologists as the Central Virginia Seismic Zone, and is known to produce small earthquakes about once every five years. The Tuesday quake was the strongest tremor from this area in more than a century.

In the immediate aftermath of the quake, the Orange County 911 Center received well over a hundred phone calls from alarmed residents. However, there were no reports of injuries or structural damages.

In Kingston, Ulster County Executive, Mike Hein, ordered the evacuation of the County Government Building and all other county buildings as a precaution.

In Port Jervis, city hall and other city buildings were evacuated.

All across the region, people felt their homes shake and sway for as much as half a minute.

In Virginia, twenty miles from the epicenter, the North Anna nuclear power plant shut down after the tremors began and electricity was cut off. No radioactivity was released, and the plant was scheduled to resume operation by Tuesday night. In the towns of Mineral and Louisa, minor damage and chimney collapses were reported.

Buildings swayed and shook in Washington D.C. and New York. People in Manhattan office buildings reported elevator shut-downs and frightening moments as towers swayed.

In Washington, some damage was reported from the National Cathedral and the Washington Monument. Helicopter inspection of the monument revealed that stones at the top of the structure had cracked, although the monument was reported to be sound otherwise. At the Cathedral three five foot pinnacles had broken off the central tower, and some pieces fell onto the lawns below. The Smithsonian Institute reported cracks in internal walls. The building, now 150 years old, will be inspected for further damage.

Aftershocks of 2.8 and 2.2 magnitude followed a couple of hours later, and just after 8 pm, another one recorded at 4.2 magnitude occurred.

The quake emanated from a depth of 3.7 miles and is thought to be the result of slippage along one of a number of faults that lie within the Central Virginia Seismic Zone. This area is unlike better known earthquake zones, such as those in California, because it does not lie on the boundary of a tectonic plate. In Virginia the faults are segmented into segments generally less than ten miles long. Earthquakes from fault zones within a plate are normally less energetic than those on plate boundaries.

The CVSZ has produced moderate earthquakes for centuries, if not millennia. Tuesday's quake, while larger than usual, was simply another in the series.