The New Madrid Seismic Zone is a buried system of faults in the central United States, centred near the town of New Madrid, Missouri, and spanning parts of Missouri, Arkansas, Tennessee, Kentucky and Illinois. Unlike California's plate-edge faults, it lies deep within the stable interior of the North American Plate, making its earthquakes a rare intraplate phenomenon.
The faults are thought to reactivate an ancient failed rift, the Reelfoot Rift, buried beneath thick Mississippi River sediments, and they combine reverse and strike-slip motion. Because the old, cold and rigid crust of the continent transmits shaking efficiently, its earthquakes are felt over enormous distances.
In the winter of 1811 to 1812 the zone unleashed a sequence of at least three great earthquakes estimated between magnitude 7 and 8, which rang church bells as far away as the East Coast, reshaped the Mississippi River and created Reelfoot Lake. Scientists warn that a repeat today would be devastating for a region largely unprepared for major seismic hazard.