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- Essay Name : 1499.txt
- Uploader : Bill Tonkin
- Email Address :
- Language : english
- Subject : Environmental Awareness
- Title : The Earthquakes of 1811 and 1812 in the Mississippi River Valley
- Grade : A
- School System : NC university syster
- Country : use
- Author Comments :
- Teacher Comments : Great paper
- Date : 11-12-96
- Site found at : lycos
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- When one thinks of earthquakes, the Mississippi river valley (MRV), does not
- frequently come to mind. One usually thinks of one of California's numerous faults or
- somewhere in Alaska. However, little known to the general public, there were two
- massive earthquakes in the MRV, which rank among the top three in the contiguous
- United States and in the top ten for the entire United States (http://wwwneic.
- cr.usgs.gov/neis/eqlists/bigten.lis). Starting in the early morning hours of December 16,
- 1811 a violent shaking of the earth began, which continued on for three months,
- producing two of the three largest quakes in the contiguous US, this particular quake
- registered an 8.0 in magnitude on the Richter scale. There was a second quake on
- February 7, 1812 which registered 8.2 (http://wwwneic.cr.usgs.gov/neis/eqlists/
- bigten.lis).
- The plate which is responsible for this activity is named the New Madrid Seismic
- zone, it is named for the only populated city that was in existence in the time and the area
- of these earthquakes, New Madrid, Missouri. The New Madrid Seismic zone lies in the
- central MRV, starting in southern Illinois and ending in southeast Missouri, western
- Tennessee.
- Usually an earthquake consists of a principal shock and then the aftershocks, the
- 1811-1812 earthquakes didn't follow the usual pattern. There was the first primary shock,
- at and then it's aftershocks, however the aftershocks from the first quake hadn't subsided
- before the second principal shock hit. Following suite, the aftershocks from the second
- quake had not terminated when the third and largest principal shock hit (http://www.eas.
- slu.edu/Earthquake_Center/Nuttli.1973/intensity.html). It is difficult to gage the actual
- intensity of the earthquakes due to the lack of technology, however, the strength can be
- estimated by the damage caused by the quakes and also by the journals of the people
- settling this part of the country. Fortunately, a man by the name of Jared Brooks, who
- was a resident of Louisville KY, kept a journal of the seismic activity from December 16,
- 1811 to May 5, 1812. He had devised his own system of measuring intensities with a set
- of horizontal pendulums from 1 to 6 inches in length and a set of vertical spring- mass
- systems. Devising his own instruments, he also created his own categories of intensities,
- with six levels. The first is comparable to an eight on the Modified Mercalli scale, second
- level is a five to a six, third is a four to five, fourth is a three, the fifth level is comparable
- to a two on the MM, the sixth is a one (http://www.slu.edu/Earthquake_Center/
- Nuttli.1973/Magnitudes.html). With the assistance of these measurements scientist have
- been able to devise approximate strengths of these earthquakes. The following is a map
- with the MM intensity values for the December 16, 1811 earthquake. Map
- (http://www.eas.slu.edu/Earthquake_Center/Nuttli.1973/Intensity.html)
-
- Through some in depth research about ground motions and intensities of these
- earthquakes, if has been concluded that the epicenter of the first earthquake (December
- 16, 1811) was closer to the northeast Arkansas near the southern end of the lake formed
- by the St. Francis River. The lake in the area was raised as much as 12 ft. up higher than
- the surrounding country. The water in the lake was drained and replaced by white sand.
- It was stated by the Louisiana Gazette that the river itself rose as much as 25 to 30 feet
- above it's banks (http://www.eas.slu.edu/Earthquake_Center/Nuttli.1973/Intensity.html).
- There are several published personal accounts of these earthquakes, the following
- is an collection of excerpts from a letter found in a book entitled, "Lorenzo Dow's
- Journal," published by Joshua Martin, printed by John B. Wolff, 1849, on pages 344-346.
-
- 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.
-
- 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 (http://www.hsv.com/genlintr/newmadrd/
- accnt1.htm).
- This is a very powerful account of the first and second primary shocks. Having
- never been in an earthquake I cannot imagine "the earth visibly waving as a gentle sea".
- There are several other published accounts, however, none as descriptive and powerful as
- this one.
-
-
- References
- http://www.eas.slu.edu/Earthquake_Center/NewMadrid/General.html
- http://www.eas.slu.edu/Earthquake_Center/Nuttli.1973/Intensity.html
- http://www.eas.slu.edu/Earthquake_Center/Street/rstreet.html
- http://www.hsv.com/genlintr/newmadrd/accnt1.htm
- http://www.slu.edu/Earthquake_Center/ Nuttli.1973/Magnitudes.html
- http://wwwneic.cr.usgs.gov/neis/eqlists/bigten.lis
-
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