I live in S Illinois and we had one 6 or 7 years ago that was 4.1 (New Madrid.) Middle of the night and scared the crap outta us. Shook the heck out of the house.
Next morning I added an earthquake rider onto my homeowners.
The New Madrid fault zone is the result of something that happened over 600 million years ago, when the pre-Pangea super-continent of Rhodina was breaking apart. When supercontinents break apart they do so in a 3-prong process. Ultimately one of the three prongs "fails" and spreading continues along the remaining two. This is what happened there.
It is also what is currently going on in the area of the Great Rift Valley in Africa, the Red Sea, and the Gulf of Aden.
If New Madrid rips then the insurance policy is probably worthless. The damage will cause a major financial disruption on top of the physical damage.
I was up during that one. It was like between 3 and 4 in the morning.