Last week's minor earthquake not serious

A minor earthquake that rattled parts of Amherst and Nelson counties last week did not signal a serious danger, and such quakes occur on average about three times a year, according to the Virginia Tech Seismological Observatory.

“These are usually in the magnitude 2.5 to 3 range,” said Martin Chapman, director of the Tech observatory.

“Faults are common throughout the region, but most of the mapped faults show no evidence for geologically recent movement,” he said.

A fault, along which earthquakes occur, is a break in the continuity of a body of rock or of a vein, with dislocation along the plane of the fracture.

“The most likely faults associated with (Virginia) earthquakes are relatively minor features that developed in the Mesozoic Period, and most of these are not mapped,” Chapman said.

The 1989 Loma Prieta earthquake in the San Francisco Bay area, which occurred during the World Series, occurred on the San Andreas Fault. The famous 1906 San Francisco earthquake occurred on the same fault, which largely destroyed the city and first revealed the significance of faults.

Sometimes, a series of small earthquakes occur, known as a swarm. “Swarms of earthquakes are often experienced in central Virginia,” Chapman said. “The most recent such swarm occurred (during the summer) near Richmond.”

According to the seismological observatory, the first such quake a magnitude 2.3 and occurred around midnight July 6 and July 7. Smaller or equal quakes occurred through Aug. 3.

Sequences of small quakes have occurred in the Central Virginia seismic zone on several occasions during the past 30 years, according to the observatory.

For more information on the local earthquake and others in the Commonwealth this year, visit www.geol.vt.edu/outreach/vtso.

No one was reported injured in the local quake.

Chapman said the recent quake began about 5:25 p.m. last Wednesday, Nov. 25, and was measured between 2.7 and 2.8 in magnitude. Its epicenter was near Gladstone on U.S. 60, about 10 miles east of Amherst.

The Amherst County 911 Center received several phone calls around 5:30 p.m. from residents in northern Amherst County who experienced the ground and their houses shaking, said Amherst County’s public safety director, Gary Roakes.

Roakes said that some residents reported pictures falling from the walls and one man reported the gutter on his roof had fallen during the tremors. No major damage resulted, he said.

Nelson County Emergency Services Coordinator Ray Uttaro said that he had also received calls from residents, many of whom believed the rattles were the result of an explosion.

Gladstone Rescue Squad member Jerry Coffey said that he experienced the quake but other than a few tremors, there was no significant impact.

“It shook and it rattled. You could feel gravel shuffling under your feet,” Coffey said.

Chapman said that earthquakes of this size are routine in Virginia and typically occur every three or four months somewhere in the state.