Seismic data spurs worries of possible New Madrid quake
Fault spawned worst temblor in nation's history in early 1800sBY PATRICK O'DRISCOLL
GANNETT NEWS SERVICE
The sleeping giant of U.S. earthquake faults, the New Madrid zone in the heartland, may be showing new signs of activity.
The journal Nature reported in June that a University of Memphis study detected a half-inch of fault shift in the past five years. The movement, detected with a global positioning system, could mean pressure is building toward a significant quake in a region that is home to millions of people.
"We go from nothing moving to a little movement. That's a huge difference," said Arch Johnston, director of the university's Center for Earthquake Research and Information.
The New Madrid (pronounced MAD-rid) zone is the most seismically active region east of the Rocky Mountains. It is a 120-mile series of rifts deep beneath eight states along the Mississippi River.
Almost two centuries ago, it produced the largest quake ever to strike the continental United States.
The earthquake, later estimated at 8.1 magnitude or higher, was stronger than any in California, home of the San Andreas fault.
But the New Madrid fault, named for the frontier Missouri village rocked by powerful quakes in the winter of 1811-12, hasn't had a big one since. The last of considerable strength, estimated about 6.0, was in 1895. More than 100 quakes a year occur in the zone, which runs from northeastern Arkansas to southern Illinois. Most are too small to be felt.
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