The New Madrid Fault Zone is a source of earthquakes which lies along the Mississippi River.
The zone is named after the town of New Madrid, Missouri, the site of three of the most severe North American earthquakes in recorded history.
These earthquakes, which occurred in late 1811 and early 1812, were quite strong, causing changes in the course of the Mississippi and were reported to have been felt as far away as Boston, Massachusetts.
The last major earthquake to occur in this region occurred in Charleston, Missouri, in 1895, and is estimated to have had a magnitude of 6.7 on the Richter Scale.