THE NEW MADRID SEISMIC ZONE

On December 16, 1811, the 400 terrified residents of the town of New Madrid, MO were abruptly wakened by violent shaking and a tremendous roar

It was the first of three magnitude 8 earthquakes and thousands of aftershocks to rock the region that winter

In the winter of 1811-1812, the Central Mississippi valley was struck by three of the most powerful earthquakes in U.S. history

Isoseismal map for the December 16, 1811 earthquake, first of the 1811-1812 New Madrid series

The fault zone originated 750 million years ago, when the earth’s landmass was a supercontinent

At that time, a constructive fault zone began to form, but failed

It is now known as the Reelfoot Rift

Although earthquakes are less frequent here than in Western states, they effect much larger areas

The two largest probably exceeded the size of any continental US earthquake

No fewer than 18 of the earthquake events were felt on the Atlantic seaboard and in Washington DC

The series was named after the small riverboat town of New Madrid, sited at the heart of epicentral zone, which was the largest settlement between St. Louis and Natchez in 1811

Inhabitants per square mile, 1811-1812

New Madrid marks the intersection of three of the six fault segments currently illuminated by microseismicity and believed to be the rupture planes for the 1811-1812 earthquakes

Research confirms the 1811-1812 quakes cause fissuring, sand and water blows, landslides, large sunken lakes, waterfalls on the Mississippi River, and sunken forests

Kentucky historical sign

In 1811, the Mississippi Valley was sparsely populated

Today, the region is home to millions of people, including the cities of St. Louis and Memphis

Most structures in the region were not built to withstand earthquake shaking

Earthquake preparedness has lagged behind

Earthquakes recorded since 1974

Climatologist Dr. Iben Browning predicted that there would be an earthquake on the New Madrid Fault on December 3, 1990

The prediction caused quite a stir…

sources

“Contemporary Newspaper Accounts of Mississippi Valley Earthquakes of 1811-1812” slu.edu 15 January 2009 <http://www.eas.slu.edu/Earthquake_Center/SEISMICITY/Nuttli.1973/nuttli-73-app.html>

Johnston, Arch C. and Eugene S. Schweig. “The Enigma of the New Madrid Earthquakes of 1811-1812.” Earth. 24 (1996): 339-384.

“The Mississippi Valley – ‘Whole Lotta Shakin’ Goin’ On’ “ usgs.gov 15 January 2009 <http://quake.wr.usgs.gov/prepare/factsheets/NewMadrid/>

“Uncovering Hazards of the Mississippi Valley” usgs.gov 15 January 2009 <http://quake.wr.usgs.gov/prepare/factsheets/HiddenHazs/>