The New Madrid Earthquakes began on December 16, 1811 continuing with further large shocks on January 23 and February 7 of 1812. Thousands of aftershocks are also recorded as late as 1817.The first earthquakes were centered in the town of New Madrid on the Mississippi River, then part of the Louisiana Territory and now Missouri.
The New Madrid Earthquakes were some of the most powerful earthquakes to hit the eastern United States and Canada in recorded history. The earthquakes were between 7.0 to 7.7 in magnitude.
The size of the area that received strong shocks was about 130,000 square kilometres. Moderate shocks were felt across nearly 3 million square kilometres. The earthquakes were felt as far as Pittsburgh, Pennsylvania, Norfolk, Virginia and in Quebec, Canada. There are also reports of church bells ringing in Boston, Massachusetts and York (Toronto), Ontario.
By way of comparison, the U.S. Geological Survey notes that " [t]he area of strong shaking associated with these shocks is two to three times as large as that of the 1964 Alaska earthquake and 10 times as large as that of the 1906 San Francisco earthquake".
The U.S. Geological Survey further describes the physical effects as follows:The earthquakes caused the ground to rise and fall - bending the trees until their branches intertwined and opening deep cracks in the ground. Deep seated landslides occurred along the steeper bluffs and hillslides; large areas of land were uplifted permanently; and still larger areas sank and were covered with water that erupted through fissures or craterlets. Huge waves on the Mississippi River overwhelmed many boats and washed others high onto the shore. High banks caved and collapsed into the river; sand bars and points of islands gave way; whole islands disappeared. Surface fault rupturing from these earthquakes has not been detected and was not reported, however. The region most seriously affected was characterized by raised or sunken lands, fissures, sinks, sand blows, and large landslides that covered an area of 78,000 - 129,000 square kilometers, extending from Cairo, Illinois, to Memphis, Tennessee, and from Crowley's Ridge in northeastern Arkansas to Chickasaw Bluffs, Tennessee. Only one life was lost in falling buildings at New Madrid, but chimneys were toppled and log cabins were thrown down as far distant as Cincinnati, Ohio, St. Louis, Missouri, and in many places in Kentucky, Missouri, and Tennessee.What we know about these earthquakes is taken from eyewitness accounts that were recorded in letters, journals and newspaper articles.
It sometimes took months for information to reach different parts of the country. For example, on January 11, 1812, the Western Spy of Cincinnati, Ohio reported:Further accounts of it are received by every mail. At present we are unable to trace its extent, in a northern direction (east of the mountains) beyond the city of Washington, we find however, that on this side, it has been felt in much higher latitudes. In our last notice such information as had reached us by the preceding mails. But since then several shocks have been experienced in this town; indeed, there was not a day for three weeks together in which one or more were not perceived. — The Pittsburg Mercury, in speaking of the phenomenon, as felt in different places, has this observation; ‘but there is one thing more curious (or at least more uncommon) that the earthquake which is not mentioned in the papers of other towns — it is the light that was perceived at the time of the concussion.’ Now this light was visible to some in Cincinnati, and likewise at Knoxville, Tennessee where, it is said, ‘at the end of the first & longest shock there were in a direction due north, two flashes of light (an interval of about a minute between them) much resembling distant lightning.’ At Nashville (Tenn.) the same earthquake was felt, succeeded, within a few minutes of the first shock, by a ‘rumbling noise, like the rolling of a heavy body over the floor of an adjacent room.’ It is stated to have lasted between 5 and 6 minutes. Another shock (says the same account) ‘did some injury, such as displacing and knocking the tops off chimneys and several houses were moved several inches.’ We suppose the writer meant to say, the houses were rocked.— From Vincennes (I T) we learn that repeated shocks happened there on different days by which ‘two or three brick chimnies were cracked, and the roofs of several house thrown off — so says this account! — By the Pittsburgh Gazette it appears convulsions were perceived at the same time far up the Allegheny River at Meadville and Waterford, where three smart shocks were felt on the 16th and 17th ult. ——Having now before us some particulars of the earthquake, as felt at Marietta, we shall barely notice as a fact corroborative of various other statement, that by some an explosion was heard, resembling the noise made by emptying loads of small stones, or that of a carriage in rapid motion on pavement. — Concussions were also felt at Clarksburg, Va. But the account of them is too meager to merit particular notice. We are yet disappointed in hearing from the Missouri.