A minor earthquake occurred at 04:59:33 AM (EST) on Wednesday, February 10, 2010 in northeast Illinois 65 kilometers (40 miles) west of Chicago. The magnitude 3.8 earthquake occurred 5.0 kilometers (3.1 miles) underground.
For more information on this event, see this USGS website: http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/us2010snay.php
The earthquake was recorded on instruments in the Kentucky Seismic and Strong-Motion Network, operated jointly by the Kentucky Geological Survey and the Department of Earth and Environmental Sciences at the University of Kentucky.
The graphic below is the actual record of the earthquake made by 8 Network instruments.