Could New Madrid Fault break?

I long lived in southern Illinois. I had heard various estimates of the stress in that fault. While living there, in 1987 or -88 (i don't recall specifically) there was a "tremblor" (i think that is the correct term) which was not horribly damaging, but which was enough to throw me out of bed. The news reports thereafter reported that there was in excess of thirty feet of stress in the New Madrid fault. That is to say, the relative shift between the plates would have been thirty feet of rotation, were there no impediment to the movement.

There has been no major seismic activity in that fault since the quakes of 1811-12. It is considered to be long overdue.

There is another aspect of that situation which gets overlooked, but which came to my attention in reading something quite apart from the subject of seismology. I was reading Freeman's R. E. Lee. When the quakes of 1811-12 had subsided, the Mississippi River began to move east below the confluence of the Missouri and Illinois Rivers. In the late 1830's, when the Corps of Engineers were working on a vast project to improve the navigation of the Mississippi, an estimate was made that the continued migration of the Mississippi would leave St. Louis fifteen miles inland from the river by 1960. By 1840, there was already more than one hundred feet of muddy river bed exposed between the St. Louis docks and the river's edge at times of low water. The citizens of St. Louis petitioned the Congress to fund a project of the Corps of Engineers to "correct" the course of the river. They were turned down, but the Corps agreed to provide an officer if they would fund the project. Ten thousand dollars were raised by private subscription, and a not so young Lieutenant of Engineers, Robert Lee, was assigned to the project.

His solution was simple and direct. Using a low-tech steam pile driver mounted on a river boat, and the massive trunks of the "big butts"--the giant trees of the bottom land of southern Illinois--he constructed two wing coffer dams, one of about a mile in length and the other about a mile and a quarter in length. A wing coffer dam is a line of pilings which juts out into the river at an angle to the river bank. The natural action of the river fills the coffer dams with débris and silt, and soon the "Father of Waters" was again flowing in its old bed, and had returned to the Missouri side at St. Louis.

There was no one living in that portion of Illinois at the time, and a land owner on the Illinois side who brought suit lost his case. Since then, however the cities of East St. Louis and Belleville have been built on the ground formed by Lee's wing coffer dams. I have often thought about the scale of the disaster if a major earthquake strikes the region, and those buried wing coffer dams give way.

Here is a link to Wikipedia's article on the New Madrid fault.

Theres a site from Mo geo survey which is one of the best re the NMSZ.New Madrid Seismic Information
Theres a paper by Liu et al (Science v 257, 1992) which uses a "high Hazrd " return frequency algorithm and predicts areturn frequency of between 500 and 1000 years for Richter values of >8 . New data refutes that because theyve wired the Reelfoot Lake area with gps and sensors to detect any displacements of +/- 1cm as normal strain relief. The history of movement on the (indeterminate) fault zone now appears to have a frequncy that may arguably be much closer.

Like Setanta I lived in Southern Illinois/Indiana. Small tremors in the area were infrequent (but not rare) and were reported by the media (4's and 5's). Moreover, during my teenagehood a hot springs (well warm anyway~75/80 degF)) appeared in a remote area not too far from the Garden of the Gods and became a favorite place to skinny dip. It didn't last too long, as a trembler that spring sent it elsewhere or elsewhen.

In addition my granddad had a fishing shack on Reelfoot lake that I frequented as a very small child. Reelfoot is a huge very shallow lake that has some of the best Crappie fishing in the world. The local legend is that it was formed when Tecumseh stamped his foot and that the Mississippi river ran north at Memphis for two hours as it filled with water.

New Madrid is not too far from the confluence of the Mississippi and the Ohio Rivers (@ Cairo- pronounced KAYro, like the syrup). Both of these rivers are huge and slow moving at the confluence, the Ohio is bigger--but Mississippi gets the credit. The river bottoms are largely silt with a few outcroppings of lime and sandstone. The area is known for surface coal mines, relatively shallow sour crude oil wells, corn farms (goes with the river silt), and frequent Indian mounds some of which are quite extensive.

As for the New Madrid being a new hazard, it isn't--however politics often overrules science and not too far from the fault lies huge water projects (TVA dams on the Cumberland, Green and Tennessee Rivers) along with navigation dams on the Ohio and Eads weirs on the Mississippi. In addition, there's a huge DOE nuclear fuel facility at Paducah, Ky. These facilities have been retrofit to meet the New Madrid fault --almost as an aw ****, no wonder my forehead is sloped moment. So when the USGS makes these predictions of a magnitude 8, the locals simply consider the relative risk of an earthquake and compare it to the known risks of tornadoes and floods and continue on their way.

Rap

We're doomed. The New Madrid fault is gonna snap like a dry twig, and the resultant stress is going to awaken the overdue Yellowstone Caldera (Supervolcano), and it's gonna be the end of everything. But on the bright side, at least it'll put an end to the "Evolution How" thread, which should have been put out of its misery long ago.

Its still one of the funniest threads going. There are so many people just talking past each other that they almost make sense.

Hey rap, sounds like there was a lot of fishin in your past. Ive always wanted to go fishing on Reelfoot , never did.

As long as we keep getting little stress releases its good, but whenever the small events start declining into long periods of no seismic activity thats the time the fault zone gets "hung up" and a big one could hit.
In the sed record, theres evidence of at least 4 big ones (displacements seen in test pits and excavations) these are piled on top of each other so the buriedplants and tree roots are all that can be used for some "guesstimate dates" . I especially dont like earthquakes on sandy silts with high moistures. Like Savannah or Boston , the earthqua ke is magnifid by the soil's poor cohesive property, (where it, like ketchup, turns to a fluid when shaken enough). Id be more concerned about Savannah , it has a greater return frequency and is an active "trailing edge" and sits on really thixatropic soils

It's like a whole bunch of ships passing in the night who can hear each other, but can't see each other.

Some are on research vessels like Hooper's boat in _Jaws_. Rex is on a sailboat just like his icon, going wherever the wind takes him, dangling his hands in the water, splashing drops into the air and thinking the drops look like stars (so maybe they *are* stars). Others are floating by on rickety rafts disconnected from reality while dreaming they are on the QE II. And a few are zooming by on speedboats like GreenPeace lobbing bombs at anything that moves.