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.
New Madrid, Missouri, was a central point of this earthquake, the shocks there being repeated with great frequency for several months. The disturbance of the earth, however, was not confined to the United States, but affected nearly half of the western hemisphere, ending in the upheaval of Sabrina in the Azores, already described. The destruction of Caracas, Venezuela, with many thousands of its inhabitants, and the eruption of La Soufriere volcano of St. Vincent Island were incidents of this convulsion. Dr. J. W. Foster tells us that on the night of the disaster at Caracas the earthquake grew intense at New Madrid, fissures being opened six hundred feet long by twenty broad, from which water and sand were flung to the height of forty feet.