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Media Advisory: Scientists Explore Quake Zone Southwest of New Madrid
Released: 10/15/2011 3:34:15 PM

Contact Information:
U.S. Department of the Interior, U.S. Geological Survey
Office of Communications and Publishing
12201 Sunrise Valley Dr, MS 119
Reston, VA 20192
Heidi Koontz 1-click interview
Phone: 720-320-1246



Between Little Rock, Ark., and Memphis, Tenn., scientists have found evidence of an earthquake source capable of magnitude 7 or greater earthquakes located at the southwestern end of the ancient Reelfoot Rift. This is the same geologic structure that hosts the New Madrid seismic zone which is responsible for the major earthquakes that occurred in the midcontinent almost 200 years ago.  

The geologic proof includes large, visible sand blows formed by strong ground shaking, and subsurface geophysical imaging of faulting nearby. Field observations and radiocarbon dating suggest that the sand blows formed as the result of two to four earthquakes between 4,800 and 10,000 years ago.

As part of the Eastern Section of the Seismological Society of America meeting in Little Rock, Oct. 17-18, scientists from around the world will examine this evidence of the prehistoric earthquakes exposed in a trench that was excavated across one of the prominent sand blows. Geological techniques used to map sand blows, feeder dikes, and related ground failure to characterize faulting will also be shared.

When: Sunday, Oct. 16, 12 p.m.

Who: Scientists from the U.S. Geological Survey, University of Arkansas at Little Rock, and other earthquake experts from around the world.

Where:  Lee Road 232, Marianna, Ark., GPS coordinates 34.705229,-90.801787: a site of large and weathered sand blows that formed between 4.8 and 10 thousand years ago in the Marianna area. The site is approximately 1.5 hours from Memphis and 2 from Little Rock. Please contact Heidi Koontz at hkoontz@usgs.gov for exact directions.

Why:  Major earthquakes have occurred in the New Madrid area for centuries. Scientists are studying geologic and geophysical clues to better understand what has occurred prior to the historic record of earthquakes in order to better understand what is likely to occur in the future.

Click here for more information about the New Madrid Earthquake Bicentennial.


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