The fact that the Mississippi River ran backwards after the massive New Madrid earthquake of 1811 is now the stuff of legend, but did you know that it's run backwards at least twice since? It's strange, but true and had nothing to do with earthquakes either.

I tend to be something of an earthquake nut. Out of pure curiosity, I was doing research about whether or not Missouri had been hit by a tsunami before. Don't laugh. It has. The History Channel mentions a fluvial tsunami that was caused by the 1811 New Madrid quake. The shaker caused the Mississippi to run backwards for several hours based on eyewitness reports.

What I did not realize is that this wasn't the last time the Mississippi has run backwards. Knowledge Nuts mentioned that it's happened twice rather recently. In 2005, Hurricane Katrina caused the Mississippi to reverse course albeit very briefly.

They shared that Hurricane Isaac caused the same phenomenon again in 2012. Here's a snippet of the force involved that they shared:

The force from the hurricane was so strong that the river started moving water at a rate of 5,200 cubic meters per second (182,000 cubic feet per second) in the wrong direction.

That's insane wind power says Captain Obvious here. It's worth noting that the hurricanes caused river flow reversal in Louisiana while the New Madrid quake of 1811 caused a much more widespread event.

There was no Richter Scale back in 1811 so the estimated magnitude of 7.5 is only an educated guess by scientists. Let's hope we never have to witness an event strong enough to cause the mighty Mississippi to run backwards again anytime soon.

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