KSDK - A geophysicist with the U.S. Geological Survey says the USGS is officially ruling Saturday's event as an earthquake.

The quake, measuring between 2.5 to 2.6, occurred in the St. Louis metro area around 5:23 p.m. between Kirkwood and Festus and Belleville and Washington.

Within minutes of the event NewsChannel 5 was contacted by hundreds of people by phone, email, and on Facebook wanting answers.

At first, the USGS hadn't heard about anything happening in our neck of the woods, but promised to look into the event. A short time later they called back and told KSDK, after some searching, that they had found the source of the event thousands felt across the region.

But knowing where it happened was only part of the solving this mystery.

People felt the event in Arnold, Imperial, Festus, Kirkwood, Crestwood, and Ladue just to name a few communities.

Steven and Julie Healy were home in Kirkwood when it happened. Steven is an avid earthquake fan and went to the internet to find out what he and his wife felt. He found a seismic reading from the Jefferson College seismograph.

But there was something strange about what he was seeing; the telltale crescendo of waves was absent. The graph spikes violently, then dissipates, no aftershocks follow.

"My first thought was, that if it was not an earthquake that it was probably some sort of explosive event," Steven said.

But Don Gearhart, of Crestwood, is skeptical. He was sitting on his deck when it happened.

"I have lived here for 21 years, and this is the first time I felt this little shake. I don't know if it was a mine detonation."

According to the USGS, a mine detonation could register up to a magnitude 3.

Not far from the epicenter of the seismic event is the Pea Ridge rare earth mine. According to the USGS, the event happened about 1 kilometer below the earth's crust.

Attempts to reach the company who owns the mine were unsuccessful, and our calls have not been returned.

The USGS also provided NewsChannel 5 with the longitude and latitude of the epicenter, which also happens to be right were the Amberleigh Woods subdivision is being built.

According to a neighbor of the subdivision, the contractors have been blowing stuff up to clear the way for construction.