CAPE GIRARDEAU, Mo. - New research by the U.S. Geological Society suggests that while the New Madrid Seismic Zone hasn’t produced a major earthquake in more than 200 years, the risk remains.
The Southeast Missourian reports that scientists used new technology to develop high-resolution imagery of the seismic zone centered around New Madrid, Mo. The imagery allows for more detailed mapping, showing weak rocks in the zone that are found deeper in the earth’s mantle compared to surrounding areas.
The weak mantle rocks have low seismic velocity, which means they are more susceptible to concentration of tectonic stress and more mobile.
Findings were published recently in the Earth and Planetary Science Letters journal.
The seismic zone produced substantial earthquakes, including three greater than magnitude 7, in 1811 and 1812. The quakes were so strong that the Mississippi River reportedly flowed backward and church bells rang as far away as New England.
Front Section, Pages 3 on 10/07/2013