Big quake might ravage U.S. Midwest

The New Madrid seismic zone -- where Missouri, Kentucky, Arkansas, and Tennessee meet -- is in the middle of the North American tectonic plate, National Geographic News reported Wednesday. The zone has three to five faults stretching about 120 miles.

Geophysicist Mark Zoback at Stanford University in Palo Alto, Calif., has studied the New Madrid system for three decades and told NGN although major quakes have previously occurred in that area, modern cities in the New Madrid zone are not prepared for such an event and could be destroyed in a major earthquake.

Long-term records suggest large earthquakes have occurred infrequently in the New Madrid area during the last 65 million years -- approximately once every million years. But Zoback told NGN the short-term record suggests there have been at least two, and perhaps as many as four, magnitude 7 events during the last 2,000 years.

Zoback and his colleagues presented their findings in February, during a meeting of the American Association for the Advancement of Science.

Copyright 2006 by United Press International