No, what you might have felt overnight wasn't the rumble of South Jersey shoppers charging to the mall for early Black Friday bargains. It was a bona-fide geological shake-up.

An earthquake of 2.1 magnitude on the Richter Scale shook the region at about 12:13 a.m.  The borough of Clementon, in Camden County, was the epicenter.

Most people, though, probably slept right through it.

"It's very unusual that people actually feel a 2.1 magnitude earthquake," said Paul Caruso, a geophysicist with the United States Geological Survey.  Worldwide, about a million quakes of at least that intensity occur each year.

But a 2.1 on the East Coast actually feels stronger than the same quake would on the West Coast, Caruso said.

"In the eastern U.S. people feel smaller earthquakes than they do say in California because the rocks are much older and so they transmit the energy a lot better," he said.

The last quake of much substance that centered in South Jersey was a 2.5 recorded in 1993. Residents are more likely to recall the 5.8 that hit Washington, D.C., in August 2012 and shook the Mid-Atlantic region for a full minute.

As far as this one goes, no damage has been reported.