Central US Seismicity Map
This map shows earthquakes (circles) of the New Madrid and Wabash Valley seismic zones (orange patches). Red circles indicate earthquakes that occurred from 1974 to 2002 with magnitudes larger than 2.5 located using modern instruments (University of Memphis). Green circles denote earthquakes that occurred prior to 1974 (USGS Professional Paper 1527). Larger earthquakes are represented by larger circles.

The 1811-1812 New Madrid sequence consisted of three large earthquakes:

  1. M~7.5 on December 16, 1811
  2. M~7.3 on January 23, 1812
  3. M~7.5 on February 7, 1812

The first earthquake was followed by 6 aftershocks in the range M5.5-6.3 in the first 2 days. Hundreds of aftershocks were felt in 1813.

The geologic record of pre-1811 earthquakes reveals that the New Madrid seismic zone has repeatedly produced sequences of major earthquakes, including several of magnitude 7 to 8, over the past 4,500 years.