The tale of what happens to the Mississippi and Ohio Rivers in a great earthquake on the New Madrid Fault is found in Book 2, Broken River.
When a great earthquake strikes on the New Madrid, it inflicts the most damage upon man-made structures in its vicinity. Two hundred years ago those structures consisted of log cabins and a few tents. The river was wild and free roaming with only a few log-boats floating down, drifting in its current.
Today the rivers are themselves man-made structures, reformed by the Army Corps of Engineers and the Mississippi Levee Authority. Levees and revetments line their sides, weirs control their flow, locks control their traffic, and dams form lakes where there once were valleys. The rivers have become a great transportation system. They are now a structure that can be broken, and broken catastrophically.
Captain BuddyJoe Simpson pilots the towboat LadyBird Jamison with twelve barges of grain downriver past Caruthersville when the earth begins to shake. The Bella Queen excursion boat and its one hundred plus passengers are just departing the dock at Caruthersville with Captain Barney Ruggs at the helm. Both boats hold in the middle of the river where the water protects them from the hard shaking, but others along the river are not so fortunate.
Virgil watches the Interstate-255 bridge fall into the flooded waters of the Mississippi. Charlie and Sylvie Greene watch the 250 foot bluffs of Fort Pillow sluff into the river, creating a twenty-foot high seiche, a wave of water, that charges up the river to engulf Osceola. Freddy and Paula, her labor induced by the trauma of the shaking, seek shelter on an empty barge from the instant quicksand produced by the vibrations near Cairo at the junction of the Ohio and Mississippi. Loretta watches the revetments protecting Caruthersville sink and water begin to flow into the town.
To the northeast, Everett watches the destruction of the Kentucky Dam and its barge locks, releasing a fifty-million cubic feet per second flow that will continue for weeks, enough to raise the already flooded Mississippi by six feet and more when the flood reaches Caruthersville.
When the shaking ends, Barney tries to move his excursion boat down river and his boat snags the remains of the I-255 bridge. BuddyJoe must find some way to save the Bella Queen from the impending flood. Later BuddyJoe hears over the river radio that Bessie's Neck has been broken, and the Mississippi has changed its course, creating a mile and a half wide, ten-foot high waterfall.
After saving the disabled Bella Queen from the flood, BuddyJoe guides a mix of refugees downriver towards Memphis. He must avoid the multitude of crevasses created by the fallen levees, fight with the river pirates spawned in the anarchy on the riverbanks, and shoot the rapids created by the underwater dam formed from the Fort Pillow bluffs.
When the flotilla arrives in Memphis and BuddyJoe ties up to the bank, the passengers all thank him, but he realizes that those on the boats were far better off on the water than they will be on dry land. Now he must find a way to help those in the lost city.