The 1811-1812 New Madrid sequence consisted of three large earthquakes:
- M~7.5 on December 16, 1811
- M~7.3 on January 23, 1812
- 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.