Great American Plains – EARTHQUAKES of 1811 and
1812
By Mary Trotter Kion
If they didn't hurry away from New Madrid, Missouri
ancient trees were uprooted and pitched into the
the ground was going to eat them alive! This was how
turbulence. For some time navigation was near
people felt after the earthquake that occurred on
impossible as well as extremely deadly.
December 16, 1811. It turns out the smaller foreshocks
were just a warning.
The death rate caused by the quake was slight due to the
sparse population. But the earth was horribly torn to
This quake, which was followed by three additional
pieces. Hundreds of acres, at various times, were
ones, is estimated by modern methods to have registered
covered with sand, water and coal that had spewed from
between 7.2 to over 9.5. The second quake occurred
great fissures. During the quake five towns in three
January 23, 1812, followed by a third quake on January
states disappeared. Many islands in the Mississippi River
27th. February 13th brought a final tremor that lasted
vanished while lakes formed where none had previously
nearly an hour and caused as much damage as the
existed.
previous three combined. The major quakes, their 200 or
so fore shocks, and their some 3,800 aftershocks were
New Madrid, Missouri sunk some one hundred fifteen
felt from the Rocky Mountains to the Atlantic coast and
feet. Cabins and stone chimneys toppled as people fled
from Mexico to Canada.
into the dark night, attempting to save their lives. A halfmile below this town on the bank of the Mississippi
In 1811 science had no means by which to predict
River there was little sign of the quake. And yet, back a
earthly disturbances but Shawnee Chief Tecumseh had
short distance many large ponds and lakes had nearly
been prophesying this devastating upheaval for the past
dried up with the beds of some elevated ten to fifteen
two years. It was to be a great sign for all tribes to rise
feet above their former banks.
up and unite against the white invaders. There is no
explanation of how this Indian leader knew the exact
Far beyond the borders of Missouri the quake was felt.
date and time of this earthquake that caused the
In Charleston, South Carolina it was reported that six
Mississippi River to reverse its course, thus creating 18
distinct shocks occurred with vibrations causing clocks
mile long Reelfoot Lake in Northwestern Tennessee.
to stop, as well as church bells to ring there and in
Washington D.C.
Many had theories about the cause of the quakes.
Because of pumice and other volcanic matter discovered
THE NEW MADRID FAULT
along several rivers some believed a volcano to the Far
West, or in the Andes, had erupted. Other theories
concerned subterranean fires, interior combustion and
The New Madrid Fault System extends 120 Miles
fermentation, electric fluid, or possibly terrestrial and
southward from the area of Charleston, Missouri, and
atmospheric electricity. Another idea was that the earth
Cairo, Illinois, through New Madrid and Caruthersville,
and the moon had come in contact with each other.
following Interstate 55 to Blytheville and on down to
Marked Tree, Arkansas. It crosses five state lines and
During that period of time a comet was passing over
cuts across the Mississippi River in three places and the
westward and some thought it had struck a mountain in
Ohio River in two places. The Fault is Active, averaging
California. Others were certain God was punishing man.
more than 200 measured events per year (1.0 or more on
Many believed the quakes indicated the end of the
the Richter scale), about 20 per month. Tremors large
world. One fellow, using logic, determined the Day of
enough to be felt (2.5-3.0 on the Richter scale) are noted
Judgment could not be at hand. Though he had been
annually. Every 18 months the fault releases a shock of
rudely bounced from his bed in the darkness by the
4.0 or more, capable of local minor damage. Magnitudes
disruption he was convinced that "Judgment Day" could
of 5.0 or greater occur about once per decade, can do
not come at "night."
significant damage and be felt in several states.
For those traveling on the rivers it surely must have
seemed like the end. One man reported waterlogged
trees rising from the bottom of the river. This situation
was observed by many. To this man it seemed as though
every tree that had been deposited in the river since
Noah's flood had surfaced. The Mississippi River
changed course in many places as banks caved in and
The highest earthquake risk in the United States outside
the West Coast is along the New Madrid Fault.
Damaging temblors are not as frequent as in California,
but when they do occur, the destruction covers over
more than 20 times the area because of underlying
geology.
A damaging earthquake in this area (6.0 or greater)
occurs about every 80 years (the last one in 1895). There
is a 50% chance of such a quake by the year 2000. The
results would be serious damage to schools and masonry
buildings from Memphis to St. Louis.
A major earthquake in this area (7.5 or greater) happens
every 200-300 years (the last one in 1812). There is a
10% chance of such a disaster by the year 2000 and a
25% chance by 2040. A New Madrid Fault rupture this
size would be felt throughout half the United States and
damage expected in 20 states or more. Missouri alone
could anticipate losses of at least $6 billion from such an
event.
The Great New Madrid Earthquake of 1811-12 was
actually a series of over 3000 shocks in three months,
five of which were 8.0 or more in magnitude. Eighteen
of these rang church bells on the Eastern seaboard. The
very land itself was destroyed in the Missouri Bootheel,
making it unfit for farming for many years. It was the
largest burst of seismic energy east of the Rocky
Mountains in the history of the U.S. and was several
times larger than the San Francisco quake of 1905.
When will another great earthquake happen the size of
those in 1811-12? Several lines of research suggest that
the catastrophic upheavals like those in 1811-12 visit the
New Madrid region every 500-600 years. Hence,
emergency planners, engineers, and seismologists do not
expect a repeat of the intensity of the 1811-12 series for
at least 100 years or more. However, though the chance
is remote, experts assign a 1% probability of an 8.0 or
greater seismic event by the year 2000 and a 3%
probability by the year 2040. Earthquake probabilities
for known active faults always increase with time,
because stresses within the earth slowly and inexorably
mount year by year until the rocks reach there limits, and
sudden rupture becomes inevitable.
Our greatest concerns are the 6.0-7.6 events, which do
have significant probabilities in the near future. A 6.0
shock has a 90% chance by the year 2040. Damaging
earthquakes of this magnitude are a virtual certainty
within the lifetimes of our children.
What can be done to protect ourselves? Education,
planning, proper building construction, and preparedness
are proven means to minimize earthquake losses, deaths,
and injuries. San Francisco and Armenia have both
recently experienced 6 ~ 7.1 magnitude quakes. San
Francisco was prepared; Armenia was not. San
Francisco suffered 67 deaths and less than $7 billion in
property losses. Armenia had over 25,000 deaths and
lost more than $20 billion. Missouri and the Midwest are
more prepared than Armenia, but only a fraction as
prepared as San Francisco.
While we still have time, we can get ready and cut our
losses, or we can do little or nothing and be caught
unprepared. We cannot prevent the coming of an
earthquake, but we can prevent it from being a major
disaster. Contact the Center for Earthquake Studies at
Southeast Missouri State University for free literature on
protecting yourself and your property.
The Richter Scale
What is the Richter Scale? The Richter scale of
earthquake magnitude is a measure of the energy
released at the source of an earthquake deep within the
earth. It is determined by measuring the amplitudes of
ground motion on seismograms. An earthquake has a
fixed amount of energy and only one Richter magnitude.
How Much Increase in Energy Does Each Unit of the
Richter Scale Represent? It is incorrect to say that each
unit of the Richter scale corresponds to a tenfold
increase in energy. Each unit, say from 5.2 to 6.2,
actually represents 31.6 times difference in energy
release. Every two units represent 1,000 times more
energy, and every two-tenths of a unit represents double
the energy.
If a Fault Has Lots of Little Earthquakes, Will Larger
Ones Be Prevented? The answer is, "No". However,
smaller earthquakes are believed to relieve the stress or
tension built up in the rocks. So, mathematically, the
more small earthquakes in an area the less chance for a
larger one.
For example, here is how the math works out.
A magnitude 6.0 (which is damaging) is 1,000 times
more energy than a 4.0 (which is not damaging). An 8.0
(which is devastating) is 1,000 times larger than a 6.0. In
other words, a fault would have to have 1,000 4.0 events
to prevent the occurrence of a single 6.0, or a million 4.0
events (1,000 times 1,000) to prevent a single 8.0
EARTHQUAKES of 1811 and 1812 Study questions
Name: _____________________________Date: _________________ Pd ____
1. When was the first major earthquake in this series recorded?
____________________________________________________________________________
2. Was it preceded by any warnings? ___________________________ What were the warnings?
_____________________________________________________________________________
3. When did the following 3 major quakes occur?
_____________________________________________________________________________
_____________________________________________________________________________
4. Describe the extent to which it was felt? ____________________________________________
_____________________________________________________________________________
_____________________________________________________________________________
5. List 2 theories people had about why these earthquakes happened.
________________________________________________________________________________
________________________________________________________________________________
6. Where were clocks reported to have stopped due the quakes?
_______________________________________________________________________________
7. What did the Mississippi river do in many places? ____________________________________
8. How many towns disappeared during these earthquakes? _______________________________
9. What were some other affects of the quake? _________________________________________
_____________________________________________________________________________
10. How often does an earthquake of 7.5 happen in this area? ______________________________
11. According to the 3rd paragraph on the 2nd page how many of the quakes were greater than 8.0 in
magnitudes? __________________________________________________________________
12. What does the article suggest is the best way for us to be prepared for a major quake?
_________________________________________________________________________________