the new madrid seismic zone
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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/>