Earthquakes are common in Virginia. Just not earthquakes like this.
The 5.8 magnitude trembler centered about 40 miles northwest of Richmond rumbled throughout much of the mid-Atlantic on Tuesday, shaking buildings and unnerving confused Hampton Roads residents.
The quake, the strongest in the commonwealth in more than a century, was felt as far north as Maine and as far south as North Carolina.
Before Tuesday, Virginia’s largest earthquake was an estimated 5.6 to 5.9 magnitude that hit Giles County, west of Blacksburg near the West Virginia border, in 1897. (The quake preceded seismic measuring devices, thus the estimate on its magnitude.) It was felt in 12 states, according to the U.S. Geological Survey.
For the commonwealth, those two were out of the ordinary.
Virginia averages about six earthquakes a year, most of them so small they go unnoticed.
For example, 160 occurred between 1977 and 1997 in Virginia. Only 26 were felt.
The lack of intensity contrasts with places such as California and parts of the Caribbean, which rest on major fault lines. Virginia lies in the middle of the North American plate, which stretches from the Pacific coast to the middle of the Atlantic Ocean. Major quakes are rare.
A majority of the seismic activity in the state is centered in two zones: one in Central Virginia stretching from the Richmond area to Charlottesville and another in the New River Valley in Giles County.
What causes them is not clear. Seismologists speculate the Giles County seismic zone is an extension of three faults that trend toward eastern Tennessee, one of the most earthquake-prone areas in the continental United States.
The Piedmont’s rocky undercarriage is likely to blame for the activity around Richmond.
Last Halloween, a 2.4 magnitude quake rumbled near Ashland. Earlier that October, another 2.4 mildly shook Hanover County.
In July 2010, a magnitude 3.6 earthquake centered near Gaithersburg, Md., was felt by nearly 3 million people throughout the mid-Atlantic.
Before that, the last significant quake was a 4.5 magnitude in December 2003 near Goochland.
Daily Press Reporter Cory Nealon contributed to this report.
Virginia’s big earthquakes
Aug. 23, Mineral: Minor damage reported across region; 5.8 magnitude
Dec. 9, 2003, Goochland: Pictures shake off the walls and windows rattle; 4.5 magnitude
June 25, 1995, Grayson and Smyth counties: Houses shook, no damage; 3.5 magnitude
April 23, 1959, Giles County: Chimneys damaged, articles shaken off shelves; 3.8 magnitude.
May 31, 1897, Pearisburg: The largest in Virginia’s history; (estimated) 5.6 to 5.9 magnitude
May, 3, 1897, Radford: Chimneys cracked and plaster fell from walls; (estimated) 4.3 magnitude
Sources: Virginia Tech Seismological Observatory, U.S. Geological Survey
