[visualops]

The greatest earthquake risk east of the Rocky Mountains is along the New Madrid fault system. Damaging earthquakes are much less frequent than in California, but when they do occur, the damage can be far greater, due to the underlying geology.

The New Madrid fault system, or the New Madrid seismic zone, is a series of faults beneath the continental crust in a weak spot known as the Reelfoot Rift. It cannot be seen on the surface. The fault system extends 150 miles southward from Cairo, Illinois through New Madrid and Caruthersville, Missouri, down through Blytheville, Arkansas to Marked Tree, Arkansas. It dips into Kentucky near Fulton and into Tennessee near Reelfoot Lake, and extends southeast to Dyersburg, Tennessee. It crosses five state lines, and crosses the Mississippi River in at least three places.
http://www.ceri.memphis.edu/public/facts_long.shtml

The Great New Madrid Earthquake of 1811-12 was actually a series of over 2000 shocks in five months, five of which were 8.0 or more in magnitude. Eighteen of these rang church bells on the Eastern seaboard. The very land itself was destroyed in the Missouri Bootheel, making it unfit for farming for many years. It was the largest burst of seismic energy east of the Rocky Mountains in the history of the U.S. and was several times larger than the San Francisco quake of 1905.
http://www2.semo.edu/ces/ces2.html

This PDF geological map of Kentucky shows fault lines.
http://rockyweb.cr.usgs.gov/outreach/mapcatalog/images/geology/ky_geol_11x14.pdf

[armymarinemom]

Keep in mind that if you have ever spent an enjoyable day at Reelfoot lake that it wasn't there before the earthquakes 1811-1812