Geography in the News: New Madrid Earthquake

Earthquake dangers from the New Madrid fault.

With the recent earthquakes in Haiti, New Zealand and Japan, Americans may wonder if or when such a disaster will or might happen closer to home. While most Americans know of the potential for earthquakes along the West Coast’s San Andreas Fault, fewer realize that a major fault line lies near Memphis, Tenn.

The New Madrid (MAH dred) fault is one of the most dangerous in the world. Located beneath the upper end of the Mississippi delta, the fault extends from Cairo, Ill., to Marked Tree, Ark., a distance of 130 miles (220 km). Geologists and other scientists have studied the New Madrid for many years.

gitn_1090_NGS New Madrid
gitn_1090_NGS New Madrid

According to the United States Geological Survey (USGS), the New Madrid area experienced a series of earthquakes in 1811 and 1812 that were among the strongest documented in the United States since its settlement by Europeans. The geographic area affected by the intense shaking during the quakes was two to three times larger than that of the 1964 Alaska earthquake and 10 times larger than that of the 1906 San Francisco earthquake.

Exact magnitudes of the New Madrid earthquakes are impossible to know, as there were no seismographs in North America in the early 1800s. The region around the New Madrid fault had relatively low density of European population at the time, but there were many written eyewitness accounts. Evidence of the intensity of the New Madrid quakes is present today and warns of widespread devastation, should a similar event reoccur.

Scientists have pieced together estimated magnitudes for the New Madrid quakes using journals, newspaper reports and other accounts of the ground shaking, subsidence and change to the landscape. They estimate the quakes were between magnitude 7.0 and 8.0, causing extreme ground movements both vertically and horizontally.

In northwest Tennessee, Reelfoot Lake formed when an area 20 miles (32 km) long subsided during one of the quakes and the depression filled with water from the Mississippi River. The Mississippi reportedly reversed its direction of flow for several hours immediately following the quake. Church bells rang in Montreal, Canada, and the tremors were felt in Boston.

The location of the New Madrid fault creates the potential for very destructive quakes. The most phenomenal ground motion from earthquakes normally occurs on unconsolidated sediments, such as sand, silt and gravel. Such loose earth materials have no solid material holding them together. The materials overlying the New Madrid fault are soft unconsolidated deltaic sediments deposited by the Mississippi, whose delta extends from Cairo, Ill., to the Gulf of Mexico.

When the release of built-up forces along a fault creates an earthquake, seismic waves are generated. The seismic waves cause the loose sediments to undulate in wavelike forms, just as the water moves in waves when a pebble is dropped into a lake. If the water table is near the earth’s surface, the undulation creates a mixing action, called liquefaction. Buildings and other hardened structures are often unable to withstand exaggerated earth movements enhanced by soft sediments.

According to an article from ABC News Radio Online (March 2011), a major earthquake along the New Madrid fault line today would be catastrophic, potentially affecting more than 15 million people in eight states: Alabama, Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee. The USGS reports that the people most at risk from a quake of magnitude 7.0 or 8.0, however, are the approximately one million people living in the Memphis metro area.

The USGS conducted a study in 2009 reporting that a major earthquake along the New Madrid fault line could result in catastrophic loss of life and severe damage to buildings and infrastructure. Unlike California, where building codes include extensive “quake proofing” measures, buildings in cities around the New Madrid have few such requirements.

The Federal Emergency Management Agency (FEMA) also predicts that a major quake at New Madrid could displace 7.2 million people and destroy at least 15 major bridges.

Another problem altogether could result from the 15 nuclear power plants around the New Madrid region. All of the power plants are of the same or similar design as the ones that failed after Japan’s recent earthquake and resulting tsunami, according to ABC News.

The earthquake and resulting tsunami disaster affecting Japan’s Fukushima Nuclear Plan in March 2011 definitely focused attention on the regions of the United States that are vulnerable to earthquakes. The New Madrid region may be particularly unprepared to handle a major earthquake.

And that is

Geography in the NewsTM.

Sources: GITN #153, “Shake, Rattle and Roll,” November 14, 1990; GITN # 1190, “New Madrid Anniversary,” Apr. 22, 2011; http://earthquake.usgs.gov/earthquakes/states/events/1811-1812.php; and http://abcnewsradioonline.com/national-news/potential-catastrophe-earthquake-could-devastate-parts-of-us.html

Co-authors are Neal Lineback, Appalachian State University Professor Emeritus of Geography, and Geographer Mandy Lineback Gritzner. University News Director Jane Nicholson serves as technical editor. Geography in the NewsTM  is solely owned and operated by Neal Lineback for the purpose of providing geographic education to readers worldwide.

Neal Lineback has written weekly Geography in the News (GITN) articles for more than 25 years (1,200 published articles) while he was Chair of Geography and Planning at Appalachian State University and since. In 2007, he brought his daughter Mandy Gritzner in as a co-author. She is also a geographer with a graduate degree from Montana State University. GITN has won national recognition and numerous awards from the Association of American Geographers, the National Council for Geographic Education and Travelocity, among others..
  • Michael Rudmin

    It would appeareto me that the New Madrid Earthquake occurred on the fall line of the Mississippi River; therefore, it likely was a sedimentation settlement earthquake. Because of the strong nature of the quake, it may have involved the collapse of a very large cavern system in the bedrock.

    That said , I’m not so sure that another extreme earthquake is so likely there, in the near future.

    I think that if you want to look for extreme earthquake hazards, you probably have to extend a ring centered on the Hudson Bay, through Murfreesboro, where there are known lamproites, and then look to see where on that ring earthquakes are not occurring. specifically, the earthquake line that you are looking for would involve a rotation of the north american continent around Mexico City, as the Atlantic opens and the Pacific subsumes. All those faults are north-south running and relieve some stress in the rotation.

    The reason for the ring, is that it would appear that there is a ring of kimberlite/lamproite centered on the Hudson, under the surface.

    I guess if I had to pinpoint where I thought you might have stresses, they would include: The Md/Delaware border, northern Georgia, North of the Texas Panhandle.

  • Raymond Munier

    It would have been fair to mention, in this article, that the question of seismic hazard, and claimed magnitude, have been a matter of heated debate within the scientific community. I would like to mention Seth Stein in this context an recommend the interested reader to follow the series of articles on this subject in e.g. Nature magazine.
    In short, it all boils down to the strain rate. It is very low in intracontinental settings and the build-up of stresses takes very long time, perhaps hundreds of thousand years, for a new earthquake to occur at the NMF. More likely, other intraplate faults are closer to their instability margin and a major earthquake is more likely elsewhere.

  • Ima Ryma

    In Mississippi delta span.
    From Cairo on down to Marked Tree.
    Including rural and urban,
    Lone farm and Memphis, Tennessee.
    All manmade that is built atop
    A time and place for earth to quake.
    When the New Madrid zone does pop,
    Oh what a hell that’s gonna make!
    Early 1800’s was when
    The New Madrid last shook all out.
    Not too many humans back then.
    Now a cast of millions – no doubt.

    Will New Madrid quake more or less?
    Earthquake experts can only guess.

  • Tony Hood

    It is my belief the New Madrid quakes of 1811 were due to a meteor impact to northern Mississippi and that the original ‘crease’ in the plate was formed approx. 12,900 years ago when the Moon impacted the Mediterranean…
    “Mediterranean, Appalachian, Pangaea Lunar Impact” @ archaeologica.org [‘New World’ section]
    PLEASE give it study! :-]

  • Destiney

    Was it as bad as it sounds did any one survive during the earthquak

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