The New Madrid Compendium collects eyewitness descriptions of the worst earthquake in American history. The Richter scale hadn’t been invented in 1811, but this quake would have measured 8.0:

The vibration of the earth shook down trees, thousands of willows were swept off like a pipe stem, about waist high, and the swamps became high ground, and the high land became low ground, and two islands in the river were so shaken, washed away and sunk, as not to be found.

The kicker: This happened in Missouri, rocking the state hard enough to ring bells in Boston. Seismologists say there’s a 90 percent chance of a magnitude 6.0 to 7.0 quake in the same area before 2040, affecting as much as 20 times the area of a West Coast quake. I wonder if their insurance rates reflect this?