New Madrid Fault System

If you've read the comments to Fall 1989, you'll know where this is coming from: Let's talk a bit about the New Madrid fault. First, what is it?  From the Missouri State Emergency Management Agency (SEMA) website,

      The New Madrid Fault System extends 120 miles southward from the area of Charleston, Missouri, and Cairo, Illinois, through New Madrid and Caruthersville, following Interstate 55 to Blytheville and on down to Marked Tree, Arkansas. It crosses five state lines and cuts across the Mississippi River in three places and the Ohio River in two places.

       The fault is active, averaging more than 200 measured events per year (1.0 or more on the Richter scale), about 20 per month. Tremors large enough to be felt (2.5 – 3.0 on the Richter scale) are noted annually. Every 18 months the fault releases a shock of 4.0 or more, capable of local minor damage. Magnitudes of 5.0 or greater occurring about once per decade can do significant damage and be felt in several states.

      The highest earthquake risk in the mainland United States outside the West Coast is along the New Madrid Fault. Damaging tremors are not as frequent as in California, but when they do occur, the destruction covers over more [sic] than 20 times the area because of underlying geology. 

The website continues with some history.

 A damaging earthquake in this Area, 6.0, reoccurs about every 80 years (the last one in 1895). In 2002, the U.S. Geological Survey (USGS) released new earthquake probabilities for the New Madrid Seismic Zone. For a magnitude 6.0 or greater earthquake, there now is estimated to be a 25-40% chance in the next 50 years. The results would be serious damage to schools and masonry buildings from Memphis to St. Louis. USGS also estimates a 7% - 10% chance of a 7.5 – 8.0 earthquake in the next 50 years (equal to the earthquake events of 1811-1812).

       A major earthquake in this area - the Great New Madrid Earthquake of 1811-12 was actually a series of over 2000 shocks in five months, some of 7.6 intensity and five of which were 8.0 or more in magnitude.[emphasis added - One or more of these quakes resulted in a slight re-routing of the Mississippi River!] Eighteen of these rang church bells on the Eastern seaboard. The very land itself was destroyed in the Missouri Bootheel, making it unfit even 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 1906.

The history explains why some people are spending vast amounts of time and effort in planning the response to a magnitude 6.0 or greater earthquake along the New Madrid fault system.  As alluded to by Adele (in the above-cited comments) concerning California's prospects for cataclysmic seismic activity, a large earthquake along the New Madrid fault system is a given.

 A major earthquake centered in the New Madrid seismic zone potentially is one of the most serious natural hazard threats facing the state of Missouri. Experts mostly agree that it is not a matter of if a significant earthquake occurring, but rather it is a matter of how soon one will happen. SEMA has developed a multifaceted earthquake program designed to carry out earthquake awareness and preparedness programs; Work with partners to promote earthquake loss-reduction plans, practices and policies that encourage earthquake mitigation; And develop better response and recovery capabilities through participation in earthquake training and exercises.

Moving up a notch, at the national level, FEMA is heavily involved in earthquake damage mitigation (preventing damage through construction methods and zoning, etc), earthquake recovery and response operations, and planning.  The top level FEMA website for earthquakes offers a treasure of information.  If you find the subject of earthquakes interesting, I recommend starting at the FEMA website, browsing through the various pages of information and resources presented thereon, and looking into your state's emergency management website.  The link to a state's emergency management website may be found by clicking on the state's name on the FEMA Regional Operations page. The link will be near the bottom of the page.  In addition, The Center for Earthquake Research and Information, at the University of Memphis, is a good place to find earthquake information affecting the central states of the continental USA.  Happy hunting!

Comments

[Hattie]

We are hyper-aware of earthquake dangers here on the Big Island of Hawaii. In Oct. of 2006 we had a couple of 6.0+ quakes followed by several aftershocks. I was off-island at the time but experienced a 5.2 aftershock a couple of weeks later.
A funny story: On the day of the first quake we were in Paris, and the phone rang at 2:00 a.m. local time. A friend from Washingon D.C. had called my husband's cell phone to ask if we were all right. So we turned on CNN to find out what had happened.
We returned to find widespread damage to rock walls, roads, and bridges. Our own rock wall at our house got jumbled in a few places and needed to be repaired. But the house was fine, being of wood construction and bolted to its foundation.
I have a friend who lives in Missouri. I think where she is the ground would give way in a huge earthquake. And there is so much construction in that part of the world that is not earthquake proofed at all.

[Cop Car]

Hattie--While I was gathering links for this posting, I clicked on Hawaii and saw the amount of activity that had been recorded during the last couple of years. Between the lava flows, earthquakes, and possible tsunamis, the islands have their share of "what ifs"!

[Hattie]

And don't forget hurricanes. Kauai has been whacked twice since the early eighties. The mountains seem to protect us here.

[Cop Car]

Hattie--Good catch! If I recall correctly, you had a hurricane headed your way several weeks ago. I don't recall that it hit or missed; but, it obviously wasn't a big thing for you, or I would have remembered!