1812 – The strongest in a series of earthquakes strikes New Madrid, Missouri
. The 1811–12 New Madrid earthquakes were an intense intraplate earthquake series beginning with an initial earthquake of moment magnitude (7.5 -7.9) on December 16, 1811 followed by a moment magnitude 7.4 aftershock on the same day. They remain the most powerful earthquakes to hit the contiguous United States east of the Rocky Mountains in recorded history. They, as well as the seismic zone of their occurrence, were named for the Mississippi River town of New Madrid, then part of the Louisiana Territory, now within Missouri. There are estimates that the earthquakes were felt strongly over roughly 50,000 square miles, and moderately across nearly 1 million square miles. The 1906 San Francisco earthquake, by comparison, was felt moderately over roughly 6,200 square miles. New forecasts estimate a 7 to 10 percent chance, in the next 50 years, of a repeat of a major earthquake like those that occurred in 1811–1812, which likely had magnitudes of between 7.6 and 8.0. There is a 25 to 40 percent chance, in a 50-year time span, of a magnitude 6.0 or greater earthquake.