Science: Middle America's Fault

It may some day cause another major earthquake

It was as frightening a natural cataclysm as had befallen the young nation. Buildings tumbled and forests were destroyed. Giant fissures opened in the ground, accompanied by a thunderous roar and a spreading sulfurous odor. Wrote one eyewitness: "The whole land was moved and waved like waves of the sea." The usually placid Mississippi became an angry torrent of whirlpools and rapids, overflowing its banks and possibly even briefly reversing course.

Three times, between Dec, 16, 1811, and Feb. 7, 1812, such scenes were repeated as...