Where did you find that info?
Here’s link to Wikipedia article
http://en.wikipedia.org/wiki/New_Madrid_Seismic_Zone
Earthquakes that occur there potentially threaten parts of seven U.S. states: Illinois, Indiana, Missouri, Arkansas, Kentucky, Tennessee, and Mississippi.
Here:
http://newine.wordpress.com/2010/03/21/new-madrid-far-and-wide/
Referencing:
http://www.aapg.org/explorer/2002/11nov/rift_zone.cfm
I guess I should have looked harder - it appears the map references a theory and not consensus. I just did a google image search and found the first map that included the U.S. and Canada.
Interesting, though, that it occured so soon after the uncontrolled oil seapage in the gulf. Of course, correlation doesn’t imply causality.
If we go another 60 days and have another quake along the line, it might add credence to the theory.
from the same article,
... New Madrid, trees were knocked down and riverbanks collapsed. This event shook windows and furniture in Washington, D.C., rang bells in Richmond, Virginia, sloshed well water and shook houses in Charleston, South Carolina, and knocked plaster off of houses in Columbia, South Carolina. In Jefferson, Indiana, furniture moved and in Lebanon, Ohio, residents fled their homes. Observers in Herculaneum, Missouri, called it “severe” and claimed it had a duration of 10–12 minutes.
Aftershocks were felt every six to ten minutes, a total of 27, in New Madrid until what was called the Daylight Shock, which was of the same intensity as the first. Many of these were also felt throughout the eastern US, though with less intensity than the initial earthquake.