Two hundred years ago, on December 16th, the New Madrid area of Missouri, Arkansas, and Tennessee saw the first of three major earthquakes to rock the area. This series of earthquakes remain the most powerful earthquakes to hit the eastern United States in recorded history.
In the early morning hours of December 16, 1811 an estimated around 7.7 magnitude. Six aftershocks were felt within two days of this earthquake ranging from around 5.5-6.3 magnitude. Within 6 hours of the initial quake, an aftershock of around 7.2 magnitude. This first quake caused only slight damage to man-made structures, mainly because of how scarcely populated the affected area was.
The next earthquake to occur was on January 23, 1812 with a 7.5 magnitude. By now, with 3 major quakes of at least 7.0 or larger throughout the area, the ground started to rise and fall. This caused trees to bend until their branches intertwined, and also caused deep cracks to open in the ground. Landslides also started to occur along bluffs and hillsides.
Then, finally, a 7.7 magnitude quake happened on February 7, 1812. In this quake the town of New Madrid was destroyed. After months of major earthquakes, many structures could no longer remain standing. Also, there was some uplift along a segment of this fault line which created temporary waterfalls along the Mississippi River near the Kentucky Bend. This generated upstream waves, and caused the formation of Reelfoot Lake in northwestern Tennessee, by obstructing streams.
Damage caused by a New Madrid earthquake is more widespread than an earthquake that happens in say California due to the soil and bedrock differences, and also because they are different types of fault lines. Estimates from studies done on the area show that the earthquakes were felt moderately across nearly 1 million square miles. By comparison, the epic 1906 San Francisco earthquake, which was and 7.9 magnitude, was felt moderately over roughly 6,200 sq mi.
This anniversary should remind people that earthquakes like this are still likely to happen again in this area. “From the seismic history we do know that these large quakes do repeat,” said Kent Moran, research associate at the Center for Earthquake Research Information in Memphis. According to the USGS, the probability for an earthquake in the New Madrid Seismic Zone measuring 6.0 or greater is about 25 to 40 percent likely to occur in the next 50 years. Below is an image from the U.S. Geological Survey showing the over 4000 earthquakes to hit the area since 1974.