The U.S. Geological Survey reported a 5.1 magnitude earthquake Thursday afternoon centered almost 7 miles northeast of Dover Base Housing, Delaware.
Reports indicate the aftershocks were felt as far away as New York and Philadelphia.
Earthquakes east of the Rocky Mountains are more infrequent than in the West, according to the U.S.G.S., but they tend to be felt over a much larger area than a quake of the same size west of the Rockies.
“East of the Rockies, an earthquake can be felt over an area 10 times larger than a similar magnitude earthquake on the west coast,” the agency said on its website.
“Most of the enormous region from the Rockies to the Atlantic can go years without an earthquake large enough to be felt, and several U.S. states have never reported a damaging earthquake.”
There have been no reports of damage from the Dover earthquake so far.