3.5 earthquake shakes south central Illinois overnight

A 3.5 magnitude earthquake shook south central Illinois early this morning.

The tremor happened at 1:27 a.m. near Ohlman, about 60 miles northeast of St. Louis.

No damage was reported, but more than 1,100 people reported feeling the quake from St. Louis to Springfield and Decatur.

Central Illinois is not an area known for many quakes. The entire state averages about five tremors a year, with most occurring further south near the New Madrid fault line in Missouri, Kentucky and Tennessee.

The largest modern earthquake in Illinois was a 5.4 tremor centered in Hamilton County in 1968 that caused some damage in southern Ilinois, and even reportedly toppled some chimneys in Chicago. It was felt in 23 states.

Upstate Illinois quakes are felt so far away, compared to earthquakes in other regions, because the old, rigid bedrock beneath much of the Midwest allows the seismic waves to propagate further.