Since that time two major-damage level earthquakes have happened. A magnitude 6.5 near Marked Tree, Arkansas in 1843, and a magnitude 6.8 near Charleston, Missouri in 1895. In addition, earthquakes of smaller magnitudes were felt in the past and continue to be felt periodically today. At this time it is not possible to predict the exact date, duration, or magnitude of an earthquake. Earthquakes are common in many regions of the United States and the world.
Large earthquakes are relatively rare.
The ground does not open up and swallow people, houses, etc. The New Madrid fault system does not run under the city of Memphis, or Shelby County. The closest point is 35 miles northwest of Memphis, at Marked Tree, Arkansas. Many small earthquakes do not act as a safety valve for a large earthquake. You can prevent a lot of earthquake damage.