Missouri's Feared 'New Madrid'
Fault Said Much Tamer
Than Thought
By Traci Watson
Scientists from four universities have some new advice for the good people of the Mississippi River Valley: Relax.
The notorious New Madrid earthquake area in Missouri, long regarded as on the verge of delivering a catastrophic temblor, as it did in 1811, is much tamer than thought, researchers say Friday in the journal Science.
But scientists from the U.S. Geological Survey say: Don't relax. They call the new advice irresponsible.
The new report says the risk of New Madrid erupting in a magnitude-8 quake, which could level Memphis and seriously damage St. Louis, is much smaller than previously estimated.
In fact, the researchers argue, the New Madrid seismic zone may never again be hit by a giant earthquake.
The research results "show that the hazard of a big earthquake in the New Madrid region seems to be overestimated," says co-author Andrew Newman of Northwestern University in Illinois .
The reassurance didn't come soon enough for some. Just last month, highway and bridge experts from throughout the Midwest met to discuss preparations for the Big One.
The new report could mark an image change for an area that, ripped by some of the most violent quakes in U.S. history, has been regarded as more seismically dangerous than Los Angeles.
Between December 1811 and February 1812, three huge earthquakes hit the New Madrid area, shaking windows as far away as Washington, D.C. Fissures split the earth, rocks flew through the air, and the Mississippi River ran backward, perhaps from lifting of its bed.
Scientists have long believed the quakes were magnitude-8s and could occur again in 500 to 800 years. A magnitude-7 shaker, they thought, could occur even sooner. Those estimates made New Madrid more likely to unleash a cataclysm than the San Andreas Fault.
But Newman and his colleagues disagree. They used the network of orbiting satellites known as the Global Positioning System to track the crawl of the ground in the New Madrid seismic zone.
They found that it creeps so slowly that 2,500 years of movement would be required before the ground was ready to produce a magnitude-8 quake.
The scientists also say they think that there might never be such a quake there again. Their clue: the terrain, or lack thereof, around New Madrid.
"If you've ever been down to eastern Missouri, (you know) it's really flat," Newman says. That indicates a lack of seismic activity. The areas around active faults, by contrast, are rugged because of all the heaving of the Earth.
So maybe the New Madrid zone had just a temporary strain on it. Having blown the pressure in the 1800s, the area might have settled down for good.
But geological survey scientists strongly disagree. Among other things, they criticize the new report's assumption that the New Madrid seismic area behaves like other quake faults.
"In this part of the world, we don't know what causes earthquakes at all," survey seismologist Joan Gomberg says. " It's irresponsible to make pronouncements about seismic hazard."