The Federal Emergency Management Agency said if earthquakes strike in what geologists define as the New Madrid Seismic Zone, they would cause "the highest economic losses due to a natural disaster in the United States."

"People who live in these areas and the people who build in these areas certainly need to take into better account that at some time there is ... expected to be a catastrophic earthquake in that area, and they'd better be prepared for it," said FEMA spokesperson Mary Margaret Walker.