Hidden Hazards in the Mississippi Valley

In the winter of 1811-12, the central Mississippi Valley was struck by three of the most powerful earthquakes in U.S. history.  Even today, this region has more earthquakes than any other part of the United States east of the Rocky Mountains.  Government agencies, universities, and private organizations are working to increase public awareness of the earthquake threat and to reduce loss of life and property damage during future shocks.

The central Mississippi Valley is the most earthquake prone region of the United States east of the Rocky Mountains.  The part of the region in which most earthquakes occur is referred to by scientists as the New Madrid Seismic Zone (NMSZ).  The topography here is nearly level: the higher areas, shown here in warm colors, are only a few hundred feet above the broad Mississippi Valley, shown in blue. 

Winter of 1811-1812

The winter of 1811-12 was extremely difficult for the European settlers of the Mississippi Valley. While Tecumseh, the Shawnee chief and visionary, was attempting to unite the tribes of the valley in an effort to drive out the settlers, the region was struck by three of the most powerful earthquakes in United States history. These magnitude 8 quakes, centered near the town of New Madrid (Missouri), devastated the surrounding region and rang church bells 1,000 miles away in Boston. Damage was reported as far away as Charleston, South Carolina, and Washington, D.C.

The 400 terrified residents in the town of New Madrid (Missouri) were abruptly awakened by violent shaking and a tremendous roar on December 16, 1811, when the first of three large earthquakes struck.  Survivors reported that the earthquakes caused cracks to open in the earth's surface, the ground to roll in visible waves, and large areas of land to sink or rise.  The crew of the New Orleans (the first steamboat on the Mississippi, which was on her maiden voyage) reported mooring to an island only to awake in the morning and find that the island had disappeared below the waters of the Mississippi River.  In fact, the course of the Mississippi River was changed, creating Reelfoot Lake, which covers an area of more than 10 square miles in northwestern Tennessee.

Future Hazards

The great earthquakes of 1811-12 were not freak events.  In recent decades, earth scientists have collected evidence suggesting that strong earthquakes in the central Mississippi Valley have occurred repeatedly in the geologic past.  Small earthquakes happen in the region frequently. 

Locations of small earthquakes in the New Madrid Seismic Zone since 1974

In 1811, the central Mississippi Valley was sparsely populated and there were few man-made structures. Today, this region is home to millions of people, including the populations of large cities, such as St. Louis, Missouri, and Memphis, Tennessee.  A repeat today of the earthquakes of 1811-12 would cause widespread loss of life and billions of dollars in property damage

Another earthquake as powerful as the great quakes of 1811-12 may not occur for many years. However, scientists estimate that there is a 90% chance of a magnitude 6 to 7 temblor occurring in the NMSZ within the next 50 years. Because of differences in the geology east and west of the Rocky Mountains, the effects of a magnitude 7 quake in the midcontinental United States could be far worse than those of the 1989 magnitude 7 Loma Prieta, California, earthquake. That quake, which struck the San Francisco Bay region during the World Series, killed 63 people and caused $6 billion of property damage.