On February 7, 1812, the most violent of a series of earthquakes near Missouri causes a so-called fluvial tsunami in the Mississippi River, actually making the river run backward for several hours.

Why did the Mississippi run backwards during the earthquake?

According to the USGS, this particular earthquake occurred on a fault that actually crossed the river three times. The uplift along this fault formed a scarp or cliff that caused both a dam and waterfalls at different locations.

What caused the Mississippi river to flow backwards in 1811?

Between December 16, 1811, and late April 1812, a catastrophic series of earthquakes shook the Mississippi Valley. Towns were destroyed, an 18-mile-long lake was created and even the Mississippi River temporarily ran backwards.