Geology And Geophysics

A Critical look at the new Madrid Fault Line is it Potentially Dangerous



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Most people associate earthquakes with the west coast and the San Andreas Fault. However, the New Madrid Fault Line is actually 20 times larger than the San Andreas Fault and the potential damage it can cause is significantly higher. If geologists are reading the signs correctly, there is a high degree of likelihood that an earthquake of magnitude 6.0 or greater will occur on the New Madrid Fault Line before 2040.

Earthquakes are generally measured using the Richter scale. This scale measures the energy released deep within the earth at the source of the earthquake. It does this by measuring the amplitudes of ground motion using a seismograph. Earthquakes of magnitude 6.0 or higher will cause serious of damage. Magnitude 8.0 or higher can have devastating effects.

The New Madrid Fault Line is actually a series of faults beneath the continental crust of the Reelfoot Rift. It begins in Cairo, Illinois, and extends 150 miles south to Dyersburg, Tennessee. In between, it crosses five state lines and the Mississippi River at least three times. States that would be affected by a New Madrid earthquake would include Alabama, Tennessee, Mississippi, Kentucky, Illinois, Indiana, Arkansas and Oklahoma. St. Louis and Memphis would be severely affected. It is considered to be the greatest earthquake threat east of the Rocky Mountains. Although earthquakes east of California are less common, the underlying geology makes them much more devastating.

In 1811 and 1812, the United States experienced its biggest-ever earthquake. There were over 2,000 earthquakes along the New Madrid Fault Line over a period of five months, with at least five of them being magnitude 8.0 or higher. It was much more devastating than the notorious California earthquake of 1906, which killed over 3,000 people. The effects of the New Madrid earthquake were so strong that they were felt over 1,200 miles away. Chimneys in Canada toppled and bells in Boston and New York City rang because of the earthquake’s tremors. Eyewitnesses claimed the Mississippi River actually flowed backward at one point during the worst of the earthquakes.

Is another earthquake series like the 1812 one likely soon?

Earthquakes like the one in 1812, only occur every 500-600 years, and scientists give less than 3 percent odds that there will be another one of that magnitude before 2040. What could happen and would still be extremely devastating is a series of three 7.0 earthquakes with several 6.0 and smaller earthquakes occurring over a period of a few months.  FEMA has suggested that a 7.7 magnitude earthquake along the New Madrid Fault Line would result in approximately 86,000 casualties, with over 3,500 dead.

Earthquakes of magnitude 7.5 – 8.0 magnitude only happen along the New Madrid Fault Line every 200-300 years. The last ones were in 1812. So, the Central US has reached the 200-year mark. Current estimates by geologists give a 25 percent chance of another 7.5 magnitude earthquake happening before 2040. If it did, the effects would likely be seen in over 20 states. However, they also give odds of 90 percent likelihood that the New Madrid Fault Line will spawn a 6.0 magnitude earthquake by 2040. A 6.0 magnitude earthquake will still cause serious damage. The earthquake in Christchurch, New Zealand, in 2012 was a 6.1 magnitude earthquake. It killed 181 people, injured 1,500 and destroyed or damaged over 100,000 buildings.

In response to the possibility, many states have begun earthquake drills and have advised residents to have an emergency plan in place with family and friends. It is never a bad idea to have a planned place to meet in the case of an incident of any type. Stocking up on batteries, flashlights, food, water, tarps, first aid supplies and spare clothes is also a good idea. Emergencies can come in many forms, often unannounced. The New Madrid Fault Line shows signs of possibly being just such an emergency.

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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://earthquake.usgs.gov/learn/topics/richter.php
  • InfoBoxCallToAction ActionArrowhttp://www.ceri.memphis.edu/awareness/nmsz.html
  • InfoBoxCallToAction ActionArrowhttp://www.scchealth.org/docs/ems/docs/prepare/newmadrid.html
  • InfoBoxCallToAction ActionArrowhttp://earthquake.usgs.gov/earthquakes/eqinthenews/2011/usb0001igm/
  • InfoBoxCallToAction ActionArrowhttp://indianapublicmedia.org/news/madrid-fault-prompts-midwest-earthquake-drills-44448/