“The earthquakes of 1812 in the Mississippi Valley began in December, 1811, and continued at intervals until 1813. As a rule they were more distinguished by frequency than violence, though on several occasions they were severe and had marked effects. They extended through the valleys of the Mississippi, Arkansas and Ohio, and their long continuance was remarkable in view of the territory affected being far from any volcanic region.

“The surface of the valley of the Mississippi was a good deal altered by these convulsions—several new lakes being formed, while others were drained. Several new islands were also raised in the river, and during one of the shocks the ground a little below New Madrid was for a short time lifted so high as to stop the current of the Mississippi, and cause it to flow backward. The ground on which this town is built, and the bank of the river for fifteen miles above it, subsided permanently about eight feet, and the cemetery of the town fell into the river. In the neighboring forest the trees were thrown into inclined positions in every direction, and many of their trunks and branches were broken. It is affirmed that in some places the ground swelled into great waves, which burst at their summits and poured forth jets of water, along with sand and pieces of coal, which were tossed as high as the tops of trees. On the subsidence of these waves, there were left several hundreds of hollow depressions from ten to thirty yards in diameter, and about twenty feet in depth, which remained visible for many years afterward. Some of the shocks were vertical, and others horizontal, the latter being the most mischievous. These earthquakes resulted in the general subsidence of a large tract of country, between seventy and eighty miles in length from north to south, and about thirty miles in breadth from east to west. Lakes now mark many of the localities affected by the earthquake movements. It is only to the fact that this country was then very thinly settled that a great loss of life was avoided.”

— Charles Morris, Ed.,
The San Francisco Calamity by Earthquake and Fire, circa 1906.

Timothy Flint, a missionary traveling through the New Madrid region seven years after the earthquakes, compiled and weighed the various stories and evidences he witnessed, and came to the following summary on the effects on the region central to the quake:

 “From all the accounts, corrected one by another, and compared with the very imperfect narratives which were published, I infer that the shock of these earthquakes in the immediate vicinity of the centre of their force, must have equalled in their terrible heavings of the earth, any thing of the kind that has been recorded. I do not believe that the public have ever yet had any adequate idea of the violence of the concussions.

We are accustomed to measure this by the buildings overturned, and the mortality that results. Here the country was thinly settled. The houses, fortunately, were frail and of logs, the most difficult to overturn that could be constructed. Yet, as it was, whole tracts were plunged into the bed of the river. The grave-yard at New Madrid, with all its sleeping tenants, was precipitated into the bend of the stream. Most of the houses were thrown down.

Large lakes of twenty miles in extent were made in an hour. Other lakes were drained. The whole country, to the mouth of the Ohio in one direction, and to the St. Francis in the other, including a front of three hundred miles, was convulsed to such a degree as to create lakes and islands, the number of which is not yet known, — to cover a tract of many miles in extent, near the Little Prairie, with water three or four feet deep; and when the water disappeared, a stratum of sand of the same thickness was left in its place.

The trees split in the midst, lashed one with another, and are still visible over great tracts of country, inclining in every direction and in every angle to the earth and the horizon. They described the undulation of the earth as resembling waves, increasing in elevation as they advanced, and when they had attained a -certain fearful height, the earth would burst, and vast volumes of water, and sand, and pit-coal were discharged, as high as the tops of the trees. I have seen a hundred of these chasms, which remained fearfully deep, although in a very tender alluvial soil, and after a lapse of seven years. Whole districts were covered with white sand, so as to become uninhabitable.

The water at first covered the whole country, particularly at the Little Prairie; and it must have been, indeed, a scene of horror, in these deep forests and in the gloom of the darkest night, and by wading in the water to the middle, to fly from these concussions, which were occurring every few hours, with a noise equally terrible to the beasts and birds, as to men. The birds themselves lost all power and disposition to fly, and retreated to the bosoms of men, their fellow sufferers in this general convulsion.

A few persons sunk in these chasms, and were providentially extricated. One person died of affright. One perished miserably on an island, which retained its original level in the midst of a wide lake created by the earthquake. The hat and clothes of this man were found. A number perished, who sunk with their boats in the river.

A bursting of the earth just below the village of New Madrid, arrested this mighty stream in its course, and caused a reflux of its waves, by which in a little time a great number of boats were swept by the ascending current into the mouth of the Bayou, carried out and left upon the dry earth, when the accumulating waters of the river had again cleared their current.

There was a great number of severe shocks, but two series of concussions were particularly terrible; far more so than the rest. And they remark that the shocks were clearly distinguishable into two classes:  those in which the motion was horizontal, and those in which it was perpendicular. The latter were attended with the explosions, and the terrible mixture of noises, that preceded and accompanied the earthquakes, in a louder degree, but were by no means so desolating and destructive as the other. When they were felt, the houses crumbled, the trees waved together, the ground sunk, and all the destructive phenomena were more conspicuous.

In the interval of the earthquakes there was one evening, and that a brilliant and cloudless one, in which the western sky was a continued glare of vivid flashes of lightning, and of repeated peals of subterranean thunder, seeming to proceed, as the flashes did, from below the horizon. They remark that the night, so conspicuous for subterranean thunder, was the same period in which the fatal earthquakes at Carraccas occurred, and they seem to suppose these flashes and that event parts of the same scene.

One result from these terrific phenomena was very obvious. The people of this village had been noted for their profligacy and impiety. In the midst of these scenes of terror, all, Catholics and Protestants, praying and profane, became of one religion, and partook of one feeling. Two hundred people, speaking English, French, and Spanish, crowded together, their visages pale, the mothers embracing their children, — as soon as the omen that preceded the earthquakes became visible, as soon as the air became a little obscured, as though a sudden mist arose from the east, — all, in their different languages and forms, but all deeply in earnest, betook themselves to the voice of prayer.

The cattle, as much terrified as the rational creation, crowded about the assemblage of men, and seemed to demand protection, or community of danger. One lady ran as far as her strength would permit, and then fell exhausted and fainting, from which she never recovered. The general impulse, when the shocks commenced, was to run; and yet when they were at the severest point of their motion, the people were thrown on the ground at almost every step. A French gentleman told me that in escaping from his house, the largest in the village, he found he had left an infant behind, and he attempted to mount up the raised piazza to recover the child, and was thrown down a dozen times in succession. The venerable lady in whose house we lodged, was extricated from the ruins of her house, having lost every thing that appertained to her establishment, which could be broken or destroyed.

The people at the Little Prairie, who suffered most, had their settlement, — which consisted of a hundred families, and which was located in a wide and very deep and fertile bottom, — broken up. When I passed it, and stopped to contemplate the traces of the catastrophe which remained after seven years, the crevices where the earth had burst were sufficiently manifest, and the whole region was covered with sand to the depth of two or three feet. The surface was red with oxided pyrites of iron, and the sand-blows, as they were called, were abundantly mixed with this kind of earth, and with pieces of pit-coal. But two families remained of the whole settlement.

The object seems to have been in the first paroxysms of alarm to escape to the hills at the distance of twenty-five miles. The depth of the water that covered the surface soon precluded escape.

The people without an exception were unlettered backwoodsmen, of the class least addicted to reasoning. And yet it is remarkable how ingeniously, and conclusively they reasoned from apprehension sharpened by fear. They remarked that the chasms in the earth were in direction from southwest to northeast, and they were of an extent to swallow up not only men, but houses, “down quick into the pit.”  And these chasms occurred frequently within intervals of half a mile. They felled the tallest trees at right angles to the chasms, and stationed themselves upon the felled trees. By this invention all were saved. For the chasms occurred more than once under these felled trees.

Meantime their cattle and their harvests, both here and at New Madrid, principally perished.

The people no longer dared to dwell in houses. They passed this winter, and the succeeding one in bark booths and camps, like those of the Indians, of so light a texture as not to expose the inhabitants to danger in case of their being thrown down. Such numbers of laden boats were wrecked above, and the lading driven by the eddy into the mouth of the Bayou, at the village, which makes the harbour, that the people were amply supplied with every article of provision.  Flour, beef, pork, bacon, butter, cheese, apples, in short, every thing that is carried down the river, was in such abundance, as scarcely to be matters of sale. Many boats, that came safely into the Bayou, were disposed of by their affrighted owners for a trifle. For the shocks still continued every day; and the owners, deeming the whole country below to be sunk, were glad to return to the upper country, as fast as possible.

In effect, a great many islands were sunk, new ones raised, and the bed of the river very much changed in every respect.

After the earthquake had moderated in violence, the country exhibited a melancholy aspect of chasms of sand covering the earth, of trees thrown down, or lying at an angle of forty-five degrees, or split in the middle. The earthquakes still recurred at short intervals, so that the people had no confidence to rebuild good houses, or chimnies [sic] of brick. The Little Prairie settlement was broken up. The Great Prairie settlement, one of the most flourishing before on the west bank of the Mississippi, was much diminished. New Madrid again dwindled to insignificance and decay; the people trembling in their miserable hovels at the distant and melancholy rumbling of the approaching shocks. The general government passed an act, allowing the inhabitants of this country to locate the same quantity of lands that they possessed here, in any part of the territory, where the lands were not yet covered by any claim. These claims passed into the hands of speculators, and were never of any substantial benefit to the possessors.

When I resided there, this district, formerly so level, rich, and beautiful, had the most melancholy of all aspects of decay, the tokens of former cultivation and habitancy, which were now mementos of desolation and desertion. Large and beautiful orchards, left uninclosed [sic], houses uninhabited, deep chasms in the earth, obvious at frequent intervals, — such was the face of the country, although the people had for years become so accustomed to frequent and small shocks, which did no essential injury, that the lands were gradually rising again in value, and New Madrid was slowly rebuilding, with frail buildings, adapted to the apprehensions of the people.”

–Timothy Flint, Recollections of the Last Ten years, Passed in Occasional Residences
and Journeyings in the Valley of the Mississippi, From Pittsburg and the Missouri
to the Gulf of Mexico, and from Florida to the Spanish Frontier, Letter XX, 1826,
p. 222-228. [Additional paragraph breaks inserted for readability.]