By Annabeth Miller, SMT Editor
Two hundred years ago - Dec. 16, 1811 - the New Madrid Seismic Zone unleashed one of the most powerful earthquakes to shake the lower 48 states. It was a quake so powerful it caused waterfalls on the Mississippi River, shook houses in Charleston. S.C., and rang church bells in Boston.
The first terrifying jolt hit at 2:15 a.m., with modern estimates pinning it at 7.7 on the Richter scale. Six hours later came what is now known as the Daylight Shock, a quake of similar intensity.
Nor was the New Madrid finished. It produced a 7.5-magnitude temblor on Jan. 23, 1812, and another 7.7 quake on Feb. 7, 1812. The USGS notes that some other sources have calculated the power of the Feb. 7 quake at 8.8, a measurement that would make it the second most powerful quake to hit the 48 contiguous states and the third largest ever among the 50 states.
The New Madrid continues to rumble, but somewhat more gently. Between Dec. 7 and Dec. 12 of this year, USGS recorded six small quakes ranging from 1.0 on the Richter scale near Ridgely and Tiptonville, Tenn., to a 2.4-magnitude quake about 1 mile west-southwest of Blytheville. Arkansas has also experienced a large swarm of quakes around Greenbrier and Guy in north-central Arkansas, one a large as magnitude 4.7.
“If the Mid-South had been as populated in 1811-12 as it is now, the destruction from that Dec. 16 quake would have been incalculable,” said Deborah Tootle, associate professor for community and economic development for the University of Arkansas Division of Agriculture. “And while nothing of that magnitude has shaken Arkansas in this century, we still have enough seismic activity to remind us that we need to be prepared.”
Buildings were flattened near the epicenter in Arkansas, and chimneys toppled hundreds of miles away. Boats on the Mississippi River were overturned. And large tracts of land became like liquid, swallowing croplands, grasslands and bottomland forests, leaving surface scars visible to this day.
Over three months in 1811-12, the quakes and hundreds of aftershocks rocked the Midwest and upper South, including portions of Kentucky. They remain among the most powerful earthquakes to ever strike the United States, occurring just across the Mississippi River near Western Kentucky.
Eliza Bryan, of New Madrid wrote her eyewitness account March, 1812.
On the 16th of December, 1811, about two o'clock, a.m., we were visited by a violent shock of an earthquake, accompanied by a very awful noise resembling loud but distant thunder, but more hoarse and vibrating, which was followed in a few minutes by the complete saturation of the atmosphere, with sulphurious vapor, causing total darkness. The screams of the affrighted inhabitants running to and fro, not knowing where to go, or what to do —the cries of the fowls and beasts of every species —the cracking of trees falling, and the roaring of the Mississippi — the current of which was retrograde for a few minutes, owing as is supposed, to an irruption in its bed — formed a scene truly horrible.
And on the bicentennial of the New Madrid quakes, geologists and emergency planners say future quakes along the fault are certain — and the U.S. Geological Survey expects that eventually, some will be very damaging.
“Earthquakes can strike anywhere, at any time, and without warning,” said Julie Rochman, president & CEO, IBHS. “Effective disaster safety measures can protect lives and property, but only if action is taken before an earthquake hits.”
IBHS has a pair of free consumer guides available on its website, http://www.DisasterSafety.org, which provides information on how to effectively prepare property for an earthquake.
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