Some of the most severe earthquakes in the United States occurred not on the Pacific Coast but in the middle of the continent in southeastern Missouri near the town of New Madrid. There are many things that were unusual about the New Madrid earthquakes of 1811-1812. First, their location is a surprise. There were centered at the southeast corner of Missouri far from the seismic active zones of the mountain chains on the edges of continents, which are the boundaries of techtonic plates. Second, their magnitudes were unusually high; in the range of 8.1-8.3. Third, the pattern was unusual in that there were three shocks of about the same magnitude separated by weeks in time. The table below gives the timings of the three major shocks. There were numerous aftershocks following each major shock.
The New Madrid Earthquakes of 1811-1812
Date Time of Day Magnitude
December 16, 1811 2 A.M. 8.2
January 23, 1812 8.1
February 7, 1812 3:15 A.M. 8.3
Several towns, including New Madrid, shown on the above map were destroyed by the quakes. In Little Prairie fifteen minutes after one aftershock on December 16th water rose to waist level and the towns people had to walk through this water eight miles to reach high ground. They went on another twenty six miles over a three day period seeking refuge in New Madrid only to find it had been destroyed.
In addition to these three major quakes there were inumerable minor ones, following and sometimes preceding the major ones. One careful observer noted an average of about forty per day over a three month month period. There was a notably strong quake on January 7 but it was not of a level 8 magnitude.
The magnitudes of the quakes were estimated from the descriptions of their effects.
Some of these effects were:
The perception of the shock, even the ringing of church bells, at great distances from the quake. The December 16th quake rang church bells in Pennsylvania and in South Carolina.
The February 7th quake was said to have been felt strong enough to rattle windows in Montreal, Quebec, over a thousand miles away.
The modification of the channel of the Mississippi River.
The rising of some sections of land, the falling of other sections.
Six foot falls were created in the Mississippi River. At some points there were reports that the Mississippi ran backwards.
The creation of new ten new lakes, the largest of which was Reelfoot Lake in northwestern Tennessee. In other places the land rose and lakes disappeared.
Some islands in the rivers disappeared.
Trees broke loudly from the violent shaking.
The rising of dead trees from river and lake bottoms.
The creation of crevasses in the earth as much as ten feet wide.
Sometimes the crevasses opened and then closed spurting water and sand into the air.
The creation of water spouts rising as high as fifteen feet into the air.
The liquification of ground and the subsequent sinking of structures.
The toppling of brickwork, particularly chimneys.
People being thrown out of their beds.
There were other things that occurred such as flashes of light, loud noises and smelly gases spreading over the land. Watery sand spouts were particularly wide spread.
The water was warm.
They left holes in the ground and sometimes sand cones where the sand came down.
Sometimes chunks of wood or coal as heavy as 20 pounds were blown out of these sand spouts. The map below shows the area in which sand spouts occurred.
Wild animals were disturbed by the quakes, seeming to lose their fear of humans.
Horses reacted to the quakes by stop moving or proceding as if they were walking on ice.
The major puzzle concerning the New Madrid earthquakes is why they occurred in midcontinent.
The answer seems to be that a break in the North American plate was developing along the route of what became the Mississippi Valley.
A rift valley was developing but the fissure ended in the region of New Madrid.
The New Madrid Earthquakes of 1811-1812
Date Time of Day Magnitude
December 16, 1811 2 A.M. 8.2
January 23, 1812 8.1
February 7, 1812 3:15 A.M. 8.3
Several towns, including New Madrid, shown on the above map were destroyed by the quakes. In Little Prairie fifteen minutes after one aftershock on December 16th water rose to waist level and the towns people had to walk through this water eight miles to reach high ground. They went on another twenty six miles over a three day period seeking refuge in New Madrid only to find it had been destroyed.
In addition to these three major quakes there were inumerable minor ones, following and sometimes preceding the major ones. One careful observer noted an average of about forty per day over a three month month period. There was a notably strong quake on January 7 but it was not of a level 8 magnitude.
The magnitudes of the quakes were estimated from the descriptions of their effects.
Some of these effects were:
The perception of the shock, even the ringing of church bells, at great distances from the quake. The December 16th quake rang church bells in Pennsylvania and in South Carolina.
The February 7th quake was said to have been felt strong enough to rattle windows in Montreal, Quebec, over a thousand miles away.
The modification of the channel of the Mississippi River.
The rising of some sections of land, the falling of other sections.
Six foot falls were created in the Mississippi River. At some points there were reports that the Mississippi ran backwards.
The creation of new ten new lakes, the largest of which was Reelfoot Lake in northwestern Tennessee. In other places the land rose and lakes disappeared.
Some islands in the rivers disappeared.
Trees broke loudly from the violent shaking.
The rising of dead trees from river and lake bottoms.
The creation of crevasses in the earth as much as ten feet wide.
Sometimes the crevasses opened and then closed spurting water and sand into the air.
The creation of water spouts rising as high as fifteen feet into the air.
The liquification of ground and the subsequent sinking of structures.
The toppling of brickwork, particularly chimneys.
People being thrown out of their beds.
There were other things that occurred such as flashes of light, loud noises and smelly gases spreading over the land. Watery sand spouts were particularly wide spread.
The water was warm.
They left holes in the ground and sometimes sand cones where the sand came down.
Sometimes chunks of wood or coal as heavy as 20 pounds were blown out of these sand spouts. The map below shows the area in which sand spouts occurred.
Wild animals were disturbed by the quakes, seeming to lose their fear of humans.
Horses reacted to the quakes by stop moving or proceding as if they were walking on ice.
The major puzzle concerning the New Madrid earthquakes is why they occurred in midcontinent.
The answer seems to be that a break in the North American plate was developing along the route of what became the Mississippi Valley.
A rift valley was developing but the fissure ended in the region of New Madrid.
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