Widespread shaking was felt across much of South Jersey about 4:50 p.m. Thursday, after an earthquake was reported in Delaware.
The U.S. Geological Survey reported a 4.1 magnitude earthquake centered 6.2 miles to the east-northeast of Delaware.
The earthquake was first reported as a magnitude 5.1 by the United States Geological Survey, but was downgraded twice. According to Michigan Tech, earthquakes with magnitudes between 4.0 to 4.9 are considered "light" and cause only minor damage. There were no immediate reports of damage or injuries.
Earthquakes in South Jersey and the mid-Atlantic usually occur when slowly accumulated strain within the Earth’s crust is suddenly released along a fault line. That strain translates into seismic waves that move along the surface and within the earth.
Reports of shaking were felt as far north as Poughkeepsie, New York, to as far south as Richmond, Virginia. South Jersey residents have reported the shaking in Galloway Township as well as throughout Cape May County.
Martin Pagliughi, coordinator of the Cape May County Office of Emergency Management, said he felt the tremors.
“It seemed like an earthquake because it lasted several seconds," Pagliughi said. “It was not a sonic boom-type shaking.”
Emergency management officials received many calls after the tremors, Pagliughi said. He said his office was reaching out to the National Weather Service and U.S. Geological Survey for more information.
Since 1950, there have been nine earthquakes in the mid-Atlantic region as strong as or stronger than what was felt Thursday. Most recently, a magnitude 5.8 earthquake shook Central Virginia on Aug. 23, 2011. This caused buildings to sway across the region and millions of dollars in damage.