In the past, this region has been struck by very powerful earthquakes. The geologic structures related to the causes of earthquakes in the region are buried by deep sedimentary deposits. Using geophysical techniques, U.S. Geological Survey scientists are revealing these hidden earthquake hazards. The great earthquakes of 1811-12 were not freak events. In recent decades, earth scientists have collected evidence that strong earthquakes in the central Mississippi Valley have occurred repeatedly in the geologic past.
Small earthquakes happen in the region frequently.
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. The central Mississippi Valley is the most earthquake prone region of the United States east of the Rocky Mountains. The topography of the central Mississippi Valley is nearly level-the higher areas, shown here in warm colors, are only a few hundred feet above the broad floor of the Mississippi Valley, shown in blue.