1811–1812 New Madrid earthquakes

The 1811–12 New Madrid earthquakes refer to a series of earthquakes near the town of New Madrid, a town that is right next to the Mississippi River, in late 1811 and early 1812. They were the largest known earthquakes in the United States in recorded history.

 Description 
The first shock was on December 16, 1811. It had a magnitude of 7.5-7.9 on the Richter scale. There also was an aftershock of magnitude 7.4 on the same day.  All three main earthquakes had major aftershocks.Conevery Bolton Valencius, “Accounts of the New Madrid earthquakes: personal narratives and seismology over the last two centuries,” in Deborah R. Coen, ed., "Witness to Disaster: Earthquakes and Expertise in Comparative Perspective," *Science in Context*, 25, no. 1 (February 2012): 17-48.

They were the most powerful earthquakes to hit the contiguous United States east of the Rocky Mountains in recorded history.Historic Earthquakes New Madrid Earthquakes 1811–1812USGS The Enigma of the New Madrid Earthquakes of 1811–1812. Johnston A.C. & Schweig E.S. Annual Review of Earth and Planetary Sciences, Volume 24, 1996, pp. 339–384. Available on SAO/NASA Astrophysics Data System (ADS) "Contiguous" excludes Hawaii and Alaska, neither of which was then part of the United States.

The earthquakes occurred in and near the Mississippi River town of New Madrid. It was then part of the Louisiana Territory but is now in the US state of Missouri.


There are estimates that in the stable continental region, the earthquakes were felt strongly over an area of  and moderately across nearly 3 million km2 (1 million sq mi). The 1906 San Francisco earthquake, by comparison, was felt moderately over roughly .

 Aftermath 
Different Native American tribes interpreted the powerful earthquakes and came to a consensus that they must have meant something. For many tribes in Tecumseh's pan-Indian alliance, it meant that he and his brother, the Prophet, must be supported. (page numbers may be for a different printing.)

 Seismic zones 
Even today, earthquakes happen in the area, known as the New Madrid Seismic Zone (or NMSZ). Scientists think that before 2050, there is a chance of over 90% that earthquakes with a magnitude of over 7.0 on the Richter scale will occur here. Arthur C. Clarke wrote a story called Richter 10 that describes such a scenario.

Other seismic activity is known from fault zones within tectonic plates. They include the Charleston earthquake of 1886. It was particularly surprising since the area had almost no history of even minor earthquakes.

 References 

Category:Earthquakes in the United States
Category:1811 in the United States
Category:1812 in the United States
Category:Articles on pre-1900 earthquakes