1811–1812 New Madrid earthquakes

The New Madrid Earthquake, the largest earthquake ever recorded in the contiguous United States, occurred on February 7, 1812. (The largest recorded earthquake in the entire United States was the Alaskan Good Friday Earthquake on March 27, 1964.) It derived its name from its primary location in the New Madrid Seismic Zone, near New Madrid, Louisiana Territory (now Missouri). This earthquake was preceded by three other major quakes: two on December 16, 1811, and one on January 23, 1812. These earthquakes destroyed approximately half the town of New Madrid. There were also numerous aftershocks in the area for the rest of that winter. There are estimates that the earthquakes were felt strongly over 50,000 square miles, and moderately across nearly one million square miles. The historic San Francisco earthquake of 1906, by comparison, was felt moderately over 60,000 square miles.

Based on the effects of these earthquakes, it can be estimated that they had a magnitude of 8.0 on the Richter scale. As a result of the quakes, large areas sank into the earth, new lakes were formed (notably Reelfoot Lake, Tennessee), and the Mississippi River changed its course, creating Kentucky Bend. Nearby sections of the Mississippi River actually ran backwards for a short time. Sandblows were common throughout the area, and their effects can still be seen from the air in cultivated fields. Church bells rang in Boston, Massachusetts .

A request, dated January 13, 1814, by William Clark, the governor of Missouri Territory (the territory was renamed soon after the quake to eliminate confusion with the new state of Louisiana), asked for federal relief for the "inhabitants of New Madrid County". This was possibly the first example of a request for disaster relief from the US Federal government, which would later become the job of the Federal Emergency Management Agency (FEMA).

This area was much less developed at the time and a comparable event today would cause significant damage.

1811-1812

In the years 1811 and 1812, the strongest earthquakes occurred in this area since the Europeans settled the region. A few people wrote eyewitness accounts of this unusual natural phenomenon. Eliza Bryane, an inhabitant of New Madrid, reported in an 1816 letter:

On the 16th of December, 1811, about two o'clock, A.M., we were visited by a violent shock of an earthquake, accompanied by a very awful noise resembling loud but distant thunder, but more hoarse and vibrating, which was followed in a few minutes by the complete saturation of the atmosphere, with sulphurious vapor, causing total darkness. The screams of the affrighted inhabitants running to and fro, not knowing where to go, or what to do - the cries of the fowls and beasts of every species - the cracking of trees falling, and the roaring of the Mississippi - the current of which was retrogade for a few minutes, owing as is supposed, to an irruption in its bed -- formed a scene truly horrible.

From that time until about sunrise, a number of lighter shocks occurred; at which time one still more violent than the first took place, with the same accompaniments as the first, and the terror which had been excited in everyone, and indeed in all animal nature, was now, if possible doubled. The inhabitants fled in every direction to the country, supposing (if it can be admitted that their minds can be exercised at all) that there was less danger at a distance from, than near to the river. In one person, a female, the alarm was so great that she fainted, and could not be recovered.

There were several shocks of a day, but lighter than those already mentioned until the 23d of January, 1812, when one occurred as violent as the severest of the former ones, accompanied by the same phenomena as the former. From this time until the 4th of February the earth was in continual agitation, visibly waving as a gentle sea. On that day there was another shock, nearly as hard as the proceeding ones. Next day four such, and on the 7th about 4 o'clock A.M., a concussion took place so much more violent than those that had proceeded it, that it was dominated the hard shock. The awful darkness of the atmosphere, which was formerly saturated with sulphurious vapor, and the violence of the tempestuous thundering noise that accompanied it, together with all of the other phenomena mentioned as attending the former ones, formed a scene, the description of which would require the most sublimely fanciful imagination.

At first the Mississippi seemed to recede from its banks, and its waters gathering up like a mountain, leaving for the moment many boats, which were here on their way to New Orleans, on bare sand, in which time the poor sailors made their escape from them. It then rising fifteen to twenty feet perpendicularly, and expanding, as it were, at the same moment, the banks were overflowed with the retrogade current, rapid as a torrent - the boats which before had been left on the sand were now torn from their moorings, and suddenly driven up a little creek, at the mouth of which they laid, to the distance in some instances, of nearly a quarter of a mile. The river falling immediately, as rapid as it had risen, receded in its banks again with such violence, that it took with it whole groves of young cotton-wood trees, which ledged its borders. They were broken off which such regularity, in some instances, that persons who had not witnessed the fact, would be difficultly persuaded, that is has not been the work of art. A great many fish were left on the banks, being unable to keep pace with the water. The river was literally covered with the wrecks of boats, and 'tis said that one was wrecked in which there was a lady and six children, all of whom were lost.

In all the hard shocks mentioned, the earth was horribly torn to pieces - the surface of hundreds of acres, was, from time to time, covered over, in various depths, by the sand which issued from the fissures, which were made in great numbers all over this country, some of which closed up immediately after they had vomited forth their sand and water, which it must be remarked, was the matter generally thrown up. In some places, however, there was a substance somewhat resembling coal, or impure stone coal, thrown up with the sand. It is impossible to say what the depths of the fissures or irregular breaks were; we have reason to believe that some of them are very deep.

The site of this town was evidently settled down at least fifteen feet, and not more than a half a mile below the town there does not appear to be any alteration on the bank of the river, but back from the river a small distance, the numerous large ponds or lakes, as they are called, which covered a great part of the country were nearly dried up. The beds of some of them are elevated above their former banks several feet, producing an alteration of ten, fifteen to twenty feet, from their original state. And lately it has been discovered that a lake was formed on the opposite side of the Mississippi, in the Indian country, upwards of one hundred miles in length, and from one to six miles in width, of the depth of ten to fifty feet. It has communication with the river at both ends, and it is conjectured that it will not be many years before the principal part, if not the whole of the Mississippi, will pass that way.

We were constrained by the fear of our houses falling to live twelve or eighteen months, after the first shocks, in little light camps made of boards; but we gradually became callous, and returned to our houses again. Most of those who fled from the country in the time of the hard shocks have since returned home. We have, since the commencement in 1811, and still continue to feel, slight shocks occasionally. It is seldom indeed that we are more than a week without feeling one, and sometimes three of four in a day. There were two this winter past much harder than we had felt them for two years before; but since then they appear to be lighter than they have ever been, and we begin to hope that ere long they will entirely cease. [1]

Reelfoot Rift: epicenter of the earthquake

Reelfoot Rift: a still active fault

4000 earthquake reports since 1974

The Reelfoot Rift goes back about 750 million years, to when the entire landmass of the earth constituted a single supercontinent, designated now as Rodinia. At the time a constructive fault zone began to form, now called the Reelfoot Rift, but it failed and the zone became inactive. About 550 million years later, at the time of the supercontinent called Pangaea, the fault zone again became active, but no longer functioned as a constructive plate and remains in the same condition today. The earthquakes are therefore to be traced to seismic activity 5 to 25 km below the crust of the earth.

New Madrid seismic zone (NMSZ)

Main article: New Madrid Seismic Zone

The epicenters of over 4000 earthquakes can be identified from seismic measurements taken since 1974, which produces an image as depicted on the map to the right. It can be seen that, as stated above, the earthquakes originate from the seismic activity of the Reelfoot Rift. The zone which is strongly colored in red on the map is called the New Madrid Seismic Zone.

Today

The zone remains active today. In recent decades minor earthquakes have continued. Scientists estimate that in the next 50 years, with a probability over 90%, there will be an earthquake with a magnitude greater than 7 on the Richter scale.

The situation is more precarious than it was 200 years ago. The area is now more thickly settled, and many buildings have no earthquake resistant construction. A few states have joined forces and founded a special institute for their earthquake zone, to prepare as well as possible for a major earthquake. The Mississippi will probably present one of the incalculable problems. A few emergency funds for earthquake victims have been founded. Measures are also being ordered to mitigate any natural disaster resulting from an earthquake; thus in the construction of dams, bridges, and highways, earthquake safety is particularly being taken into account.

Understanding of this earthquake zone is growing only slowly, in comparison to awareness of the San Andreas fault, and must be increased in the face of an ongoing earthquake danger that affects the East and Midwest of the USA.

Almost 200 years after the earthquakes in 1811 and 1812, the coures of the Mississippi River as it was before the events is still visible in the landscape of the affected areas today. Along and parallel to the Tennessee/Arkansas state line, the shrunk riverbed is still present.

Additional images

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  Range comparison
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  Contemporary drawing
• Magnitude of 1811/12 quake
  Magnitude of 1811/12 quake
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  Reelfoot Rift and NMSZ
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  View to the Southwest along the former riverbed of the Mississippi River, just South of the Tennessee/Arkansas state line near Reverie, TN (2007)
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  View to the Northeast along the former riverbed of the Mississippi River, just South of the Tennessee/Arkansas state line near Reverie, TN (2007)

Trivia

In 1993, the seminal alt-country group Uncle Tupelo released Anodyne, their last album, which contained a song called New Madrid written by Jeff Tweedy. The song makes several references to the New Madrid earthquake. The song is primarily in reference to Iben Browning's prediction of a December 3, 1990 earthquake and the media frenzy regarding the event ("Mr. Browning has a prediction..."). The song is the story of a man who falls in love with a woman that comes ("from New York City") to cover the predicted earthquake. Obviously, Browning's prediction did not come true.

See also

• List of earthquakes

References

• United States Geological Survey (2003-10-15). "USGS Earthquake Hazards Program: 1811 - 1812 Earthquakes in the New Madrid Seismic Zone". Retrieved 2005-05-03.

External links

• USGS: NMSZ since 1811; also theories
• Eyewitness accounts of the earthquakes of 1811-1812
• New Madrid seismic zone