The New Madrid fault and the Great Earthquake of 1811

Woodcut illustration of the New Madrid Earthquake, from the USGS Earthquake Hazards Program

On December 17, 1811, Illinois settlers were shocked awake by violent trembling. Fields rippled and trees swayed and twisted together, breaking apart with sounds like gunshots. Sand, coal, and smoke blew up into the air as high as thirty yards as the soil liquefied. People as far away as Canada and Maryland felt the tremors. Since the earthquake occurred in a sparsely populated area, few lost their lives, but the New Madrid fault continues to pose a threat.

Some reported that the earthquake momentarily made the Mississippi River flow backward. The river changed its course in several places as new islands appeared and others disappeared in the river. Although the Richter scale did not exist at that time, the earthquake is estimated to have been equivalent to an 8.0 on the scale, a force that can destroy communities near its epicenter.

John Reynolds, the fourth governor of Illinois, recalled in his 1855 autobiography that the entire Mississippi valley shook violently during the 1811 earthquake and its tremendous aftershock the next morning. Chimneys were demolished in the American Bottom and the church bell in Cahokia rang as the building shook. Reynolds noted that there had been many smaller quakes during the years since.

For some Native Americans, the earthquake was a sign that they must support Tecumseh in his promotion of tribal unity against the United States during the War of 1812 with Great Britain.

In a November 2008 report, the U.S. Federal Emergency Management Agency warned that a serious earthquake in the New Madrid Seismic Zone could result in "the highest economic losses due to a natural disaster in the United States," predicting "widespread and catastrophic" damage across the Midwest and Alabama.