The Missouri State Genealogical Association's blog reminds us of the New Madrid Earthquake -- actually four or five earthquakes -- of 1811-1812, and links to the US Geological Survey page on it (don't miss the pictures of visible damage 90+ years later).
At the onset of the earthquake the ground rose and fell - bending the trees until their branches intertwined and opening deep cracks in the ground. Landslides swept down the steeper bluffs and hillslides; large areas of land were uplifted; and still larger areas sank and were covered with water that emerged through fissures or craterlets. Huge waves on the Mississippi River overwhelmed many boats and washed others high on the shore. High banks caved and collapsed into the river; sand bars and points of islands gave way; whole islands disappeared.
My take on it in the Chicago Reader when I had the chance to learn from the experts and read up on it:
Monday morning, December 16, 1811, on the Mississippi River in the village of Little Prairie, Missouri Territory. The ground rocked and rolled so hard it knocked people down. Sixteen-year-old Ben Chartier had been hanging around his family's cabin door, where his mother was having a smoke. "The sky turned green, and then it shook hard. My father and my cousins ran and turned the hogs out. The ground burst wide open and peach and apple trees were knocked down and then blowed up."...
Thursday afternoon, November 9, 1995, overlooking the Mississippi River from the William Campbell farm near Dyersburg, Tennessee. Over the years David Stewart has worked as a geologist, preacher, author, natural-childbirth activist, consultant, and entrepreneur. Most recently he's been in the business of reminding anyone who will listen that the big quake of 184 years ago will be back some day. And when it comes it could do more than just rattle your dishes off the shelf.
Campbell uses the seemingly solid sand-and-gravel hillside Stewart's standing on as a gravel pit. For Stewart it's a ready-made earthquake laboratory, where he can re-create Little Prairie's nightmare in miniature. He stamps his foot on the ground again and again. The ground begins to shake like jelly where he stamped. Water seeps up out of it, and his feet begin to sink. He stamps one last time, then jumps away a few feet. "Usually you get quicksand," he says. "But under the right saturation conditions you can even get quick gravel."