I woke up this morning to discover that there had been a mild earthquake in Illinois. About 4am. It struck near Virgil, IL
-- about 50 miles west of Chicago, and was only 4.3 on the ricter scale. People up here in Milwaukee reported feeling it as well.
Illinois and Wisconsin are located in the middle of the North American plate. As a result, earthquakes are quite rare around here. There are, however, a series of ancient faults across Northern Illinois, so when an earthquake does strike, it's usually less than 5.0 on the ricter scale. And there are no aftershocks.
"Earthquake Hits Northern Illinois