What is the name of the seismic zone that caused the 1811-1812 earthquakes in the central U.S.?

The seismic zone that caused the 1811–1812 central U.S. earthquakes is the New Madrid Seismic Zone. It is named after New Madrid, Missouri, a Mississippi River town near the center of the historic earthquake sequence.

The sequence began on December 16, 1811, with additional major shocks on January 23 and February 7, 1812. Because the earthquakes occurred inside the North American Plate rather than at a plate boundary, they are known as intraplate earthquakes. Their exact magnitudes remain estimates based on historical reports, with some calculated as roughly 7 or greater.

The shaking was felt across a remarkably large area, including much of the central and eastern United States. Ground effects included fissures, landslides, liquefaction, uplift, subsidence, and unusual waves on the Mississippi River. Reelfoot Lake in Tennessee formed partly because of earthquake-related subsidence.

A common mix-up is the Wabash Valley Seismic Zone, another important Midwest seismic region. It lies northeast of New Madrid but was not the source of the famous 1811–1812 sequence.