2 centuries after New Madrid quakes, what's next?

By ADRIAN SAINZ | December 16, 2011 | 12:25 PM EST

MEMPHIS, Tenn. (AP) — Two centuries ago, a series of powerful earthquakes rocked the central Mississippi River valley at what was then the western edge of the young United States.

Now some seismologists believe there could be another "Big One" in the next 50 years along the New Madrid (MAD'-rihd) seismic zone stretching between Memphis and St. Louis.

The quakes happened on Dec. 16, 1811, and Jan. 23 and Feb. 7 of 1812. They were among the strongest in U.S. history with magnitudes estimated between 7.7 to 8.1

Seismologists agree that predicting when an earthquake will strike is next to impossible. But some experts think there is a 28 percent to a 46 percent likelihood of a magnitude 6 or greater earthquake occurring around the area in the next 50 years.