Two hundred years ago today, the central Mississippi River Valley was violently shaken by the first of a series of three earthquakes of magnitude 7 – 8 and hundreds of aftershocks greater than magnitude 3. By March 15, 1812, an estimated 2,000 aftershocks had been felt, but it is likely there were tens of thousands more that were not felt or otherwise noted.

The first of these quakes struck on December 16 around 2:15 a.m., near present-day Blytheville, Arkansas, waking residents located up to 900 miles away across what is now the eastern United States. According to reports of boat captains and others on the Mississippi River, the December 16 quake and its aftershocks caused the river to fill with debris as tree-covered banks caved into the river. Other reports said the river flooded large tracks of land, created temporary waterfalls, and even ran backwards in some places.

The second of the three major earthquakes, estimated at magnitude 7.5, occurred on January 23, 1812, at about 9:15 a.m. Similar to the December 1811 earthquake, this event was also widely felt. Damage occurred in an area of about 232,000 square miles.

The third and probably the most widely felt of the three major earthquakes occurred on February 7, 1812, at about 3 a.m. There were several destructive shocks that day, the last and largest estimated at magnitude 7.7. As a result, the town of New Madrid, Missouri, was severely damaged.

Source: http://www.usgs.gov/blogs/features/usgs_top_story/200th-anniversary-of-new-madrid-earthquakes/