Why Was There An Earthquake In Illinois This Week? Will There Be Another One?

It was a shaky Monday in Illinois.

NBC Chicago reports that a 3.3 magnitude earthquake rattled parts of Illinois on Monday. It was in Coles and Cumberland Counties but it could be felt all the way from Urbana to Mount Vernon.

Two-dozen people reported the quake, which hit around 11:43 p.m. according to the USGS. Most reports were from Neoga, Mattoon, Trilla, Charleston and Lerna, but it was also felt in areas like Decatur. The earthquake's epicenter was about 195 miles east-southeast of Quincy with a depth of 5.5 miles.

Illinois' Chance Of A Big Earthquake

The Illinois Emergency Management Agency and the Department of Homeland Security say that Illinois is "at risk from 2 major seismic zones". Those two major fault lines are the Wabash Valley Fault System and the New Madrid Fault.

A bunch of smaller fault zones are in the state though. Northern Illinois has fault systems too, including the "Sandwich Fault Zone" that goes from DeKalb to Dixon. The Peru Monocline fault runs from Dixon into the western portions of LaSalle County. North of Chicago sits the Des Plaines Fault Zone, but that one doesn't have a lot of seismic activity.

Most of Illinois' earthquakes are in the southern part of the state, near the infamous New Madrid Fault, the same strong fault line that temporarily reversed the flow of the Mississippi River.

Officials say that in any 50-year time span, there's a 25%-40% chance of an earthquake with a magnitude 6.0 or greater hitting Illinois.

On average, Illinois gets about 5 earthquakes a year but we don't normally feel them, according to experts.