Scientists warn that a major earthquake could occur at any time along the New Madrid Fault. At the present time they believe there is sufficient energy stored in the fault for a major earthquake of 7.6 magnitude on the Richter Scale. However, these sources estimate that the most probable occurrence will be a smaller earthquake in the 6.0 to 6.5 size range. The chances of such an earthquake occurring before the end of the century is 40-60% and 97% for one occurring in the next 50 years. An earthquake of this size would cause damage over a large area.
Piercy, Larry R., "Earthquake Planning Checklist" (1990). Agricultural Engineering Extension Updates. 27.