1812: The strongest in a series of earthquakes strikes New Madrid, Mo. The three-month series started on Dec. 16, 1811, in the central Mississippi River valley and were felt hundreds of miles away. All were powerful, about magnitude 7 to 7.5, with many aftershocks. The last quake destroyed the town of New Madrid and severely damaged homes in St. Louis, toppling chimneys. Contemporary reports state that the ground rose along the fault, causing temporary waterfalls on the Mississippi River, creating waves that rolled upstream, and forming Reelfoot Lake by obstructing streams in what is now Lake County, Tenn. The series remains among the most powerful earthquakes in the United States and the New Madrid fault remains a concern today.