by Max Brantley
When Central Arkansas gets one of those earthquake swarms, many naturally wonder if it's a precursor of another big rumble. Maybe not.
EVANSTON, Ill. --- When small earthquakes shake the central U.S., citizens often fear the rumbles are signs a big earthquake is coming. Fortunately, new research instead shows that most of these earthquakes are aftershocks of big earthquakes (magnitude 7) in the New Madrid seismic zone that struck the Midwest almost 200 years ago.
The study, conducted by researchers from Northwestern University and the University of Missouri-Columbia, will be published in the Nov. 5 issue of the journal Nature.
"This sounds strange at first," said the study's lead author, Seth Stein, the William Deering Professor of Geological Sciences in the Weinberg College of Arts and Sciences at Northwestern. "On the San Andreas fault in California, aftershocks only continue for about 10 years. But in the middle of a continent, they go on much longer."