The seismically sleepy mid-Atlantic states were struck by a magnitude 5.8 earthquake on August 23. At 1:51 p.m. EDT on Tuesday an earthquake struck Virginia, 135 kilometers southwest of Washington, D.C. It’s among the largest temblors to strike the state in recorded history.
The quake’s epicenter was located in central Virginia about 61 kilometers northwest of Richmond, at a preliminary estimated depth of 6 kilometers. Reports of the quake were posted on the U.S. Geological Survey’s Did You Feel It? website from as far away as Ohio and New York. That’s not unusual for earthquakes on the East Coast, which are commonly felt over a wide area.
“An event of the same size is felt over a much larger area in the East, compared to the West,” says Charles Ammon, an earthquake seismologist at Pennsylvania State University in University Park.
Vibrations from an 1897 temblor centered on Virginia’s Giles County, magnitude 5.9, reached Georgia and Pennsylvania and as far westward as Kentucky and Indiana. Chimneys crumbled and visible fissures appeared during this event.
On Tuesday, buildings rattled and lights flickered as people took to the streets in the nation’s capital. Both the U.S. Capitol Building and the Pentagon were evacuated, the Associated Press reported — as was the building that houses the USGS Earthquake Hazards Program in Reston, Va. While it’s unclear if the city’s buildings suffered much structural damage from the quake, three pinnacles did snap off the central tower of the Washington National Cathedral, says Richard Weinberg, media spokesperson. Stone masons and engineers are assessing the full extent of the damage.
Earthquakes in the mid-Atlantic tend to be small — like last year’s magnitude 3.6 temblor beneath Germantown, Md. The East Coast lacks the active fault systems created by colliding continental plates characteristic of California and the West Coast. The crust that underlies the mid-Atlantic region tends to be older, cooler and more stable. The recent quake likely started on a previously unknown fault that has been dormant for a long time in the middle of the Central Virginia Seismic Zone.
The East Coast isn’t entirely immune to big ones, though. In 1886 an earthquake registering between magnitude 6.6 and 7.3 hit Charleston, S.C., damaging an estimated 2,000 buildings and killing dozens of people.
A small magnitude 2.8 aftershock gently rocked Virginia again at 2:46 p.m. Rumors, spread in some initial news reports about the event, that this latest earthquake is a foreshock coming before a larger event are just speculation.
“There’s no scientific method that could identify a foreshock,” says Ammon.
