I didn’t think they had earthquakes in Illinois, and they don’t very often.  After this one, I decided to do a little research and post it here.

This was a 3.8 magnitude quake, quite small (the one in Haiti a month ago, 7.0, was 1600 times stronger!).

Here is a map showing the earthquakes that have hit Northern Illinois in the 20th Century:

20th Century Earthquakes - Northern Illinois

This works out to about one every six years, with none over 4.0.  Here is the exact location of the tremor, which was 10 km below the surface: (more…)