[DeltAlum]

There are faults all over the country, including the Mid-West. I read somewhere, but remember no details, that there was a fairly significant quake in Colorado years ago.

ETA that I found this on the US Geological Survey webpage:

Near Denver, Colorado
11-8-1882 01:30 UTC
Magnitude 6.2
Intensity VII

This earthquake caused minor damage in Colorado and southern Wyoming and was felt slightly in Utah and Kansas. The location of this earthquake is very uncertain and has been postulated to have occurred in western Colorado or southern Wyoming.

In Denver, electricity was cut off after an iron bolt that connected an engine-driving pulley was broken in two at the electric power building; another bolt was bent out of shape. Buildings trembled violently and residents ran out of doors. Plaster fell and windows broke as far north as Laramie, Wyoming, and plaster fell from the ceiling of a building at the University of Colorado in Boulder. Observers also reported that the walls of the railroad depot in Louisville were cracked, that timbers cracked in a house at La Porte, and that walls of one house were cracked severely and plaster fell near Thompson, Colo. An aftershock on November 8 was reported to be almost as strong at the main shock in Laramie and Denver.

After posting this, I got curious and went to Google for "Earthquake in (state) I picked about ten states at random from all different areas of the country and every one had at least some history of earthquakes.