Earthquakes - New Madrid
Thu December 15, 2011
200 years after the New Madrid earthquakes, the legends live on
Friday, Dec. 16, marks the 200th anniversary of the first of the New Madrid earthquakes, a series of large tremors centered in northeastern Arkansas and southeastern Missouri.
The earthquakes of 1811 and 1812 were so big, legend has it, they made the Mississippi River run backwards.
Seismologist Susan Hough of the U.S. Geological Survey in Pasadena, Calif., says that’s actually true – at least where the fault crosses underneath the river channel.
Hough says the earthquakes didn’t make church bells ring in Boston, though – another popular story. But they did ring the bells of St. Phillip’s church in Charleston, SC.
“So my theory is that somewhere along the line, somebody confused Charleston, SC with Charlestown, near Boston and the legend was born,” Hough said.
Geophysicist Robert Williams of the USGS in Colorado says in many places, the shaking liquefied the soil underground, spewing jets of wet sand onto the surface.
Williams says many of those sandblows, as they’re called, are still visible today.
“The strong shaking at that time also uplifted and sunk some land, so we see swamplands and small lakes out there that are the result of the differential ground settlement throughout the region,” Williams said.
Shaking from the New Madrid earthquakes was felt as far away as New York.
The last of the quakes struck on Feb. 7, 1812 destroying the small southeastern Missouri town of New Madrid.
But Washington University geophysicist Michael Wysession says that overall, the earthquakes caused little damage.
“It’s important to remember St. Louis was here in 1811 and 1812, and at that time there were 5,000 or 6,000 people,” Wysession said. “And when the earthquakes happened in New Madrid, loose chimneys fell down. In fact there were towns like St. Genevieve that are much closer to New Madrid, where there was no damage at all.”
Estimates of the magnitude of the largest New Madrid quakes range up to 7.7.
New Madrid Fault / Earthquakes