Wednesday, July 3, 2024

What if this happened to the Mississippi River?

 

I was interested to read that an ancient course of the Ganges River in India, some 2,500 years old, has been discovered.


Earthquakes, caused by the shifting of Earth’s tectonic plates, have the potential to transform the face of the world. Now, for the first time, scientists have evidence that earthquakes can reroute rivers: It happened to the Ganges River 2,500 years ago.

. . .

In a July 2016 study, Dr. Michael Steckler ... had previously reconstructed the tectonic plate movements — gigantic slowly moving pieces of Earth’s crust and uppermost mantle — that account for earthquakes experienced in the Ganges Delta.

His models showed that the likely source of earthquakes in the region is more than 100 miles (160 kilometers) away from the sand volcanoes that Chamberlain and her colleagues found. Based on the large size of the sand volcanoes, the quake must have been at least a 7 or an 8 magnitude — approaching the size of the Great 1906 San Francisco earthquake.

. . .

About 50 miles (85 kilometers) away from the sand volcanoes, the scientists also found a large river channel that filled with mud at roughly the same time. This finding indicates that 2,500 years ago, the course of the river dramatically changed. The proximity of these events in both time and space suggests that a massive earthquake 2,500 years ago is the cause of this rerouting of the Ganges.


There's more at the link.

The now-demonstrated fact that a major earthquake can change the course of even a huge river like the Ganges, moving it 50 to 100 miles away from its previous course, made me think hard.  I don't know that we've ever seen the like in North America;  most of our rivers have changed course through a combination of erosion and silting (as far as I know, anyway).  However, what might happen if something like the New Madrid Fault let go in a big way?


Earthquakes that occur in the New Madrid Seismic Zone potentially threaten parts of seven American states: Illinois, Missouri, Arkansas, Kentucky, Tennessee, and to a lesser extent Mississippi and Indiana.

The 150-mile (240 km)-long seismic zone, which extends into five states, stretches southward from Cairo, Illinois; through Hayti, Caruthersville, and New Madrid in Missouri; through Blytheville into Marked Tree in Arkansas. It also covers a part of West Tennessee near Reelfoot Lake, extending southeast into Dyersburg. It is southwest of the Wabash Valley Seismic Zone.


Again, more at the link.

What's more, the New Madrid Fault runs slap bang underneath the Mississippi River.  If it really let go, it could easily produce an earthquake with a magnitude of 7 to 8 - it already has in the not too distant past.  If it were big enough, and lasted for long enough, what might that do to the biggest river on our continent?  If a waterway that big were to be displaced by 50 to 100 miles east or west, how much of our economy, our cities and our population would it take with it?  And what would happen to anything in the way?

It's a fascinating subject for speculation.  I wonder if it might make an interesting novel - perhaps set in older times, around the Civil War or Wild West period, as alternate history?  There were powerful earthquakes along the Fault in 1811-12.  What if they were repeated, say, 60 or 70 years later, at even greater intensity?

Hmmm . . .

Peter


18 comments:

Bobby Sands said...

An earthquake is the least of our worries although this hypothesis will trigger them also. Enjoy.
https://theethicalskeptic.com/2024/05/23/master-exothermic-core-mantle-decoupling-dzhanibekov-oscillation-theory/
There are many earth formations that suggest this has happened in the past.
https://x.com/nobulart/status/1806358573460468089
https://x.com/nobulart/status/1806268353306067285
https://x.com/nobulart/status/1806289032088813702
https://x.com/nobulart/status/1805731395932766435x.
https://x.com/nobulart/status/1804988052651086004
https://x.com/OMApproach/status/1799197347525599598
https://x.com/SunWeatherMan/status/1798460033216466988
https://www.youtube.com/watch?v=IPJy1Z9n6q4
https://x.com/nobulart/status/1807412891827466618
https://x.com/nobulart/status/1807398274489360707
https://www.geo.umass.edu/climate/papers2/Baker_retrospective_2009.pdf
https://x.com/nobulart/status/1807776808999301575
https://x.com/nobulart/status/1807776808999301575

John Fisher said...

See https://en.wikipedia.org/wiki/Old_River_Control_Structure

An earthquake diverting the lower Mississippi into the Atchafalaya Basin in the Civil War would have had interesting impacts on both the North and the South.

Stevearinob said...

Re: New Madrid earthquake 1811

Anonymous said...

What if the fault along the east coast goes and suddenly push the mountains up 3 inches? All that ground water flooding towards the Great Lakes.

Amahl_Shukup said...

You don't have to set the story in the distant past, as I recall the New Madrid Fault seems to have a major activity period of about 200+/- years, so the most recent earthquakes were in the 1811-1812 period... you could set the story NOW and not be too far off.

Tsgt Joe said...

The Mississippi river already wants to divert into the Atchafalaya river and the Army Corp of engineers maintains structures limiting the flow of water. It wouldnt be too much of a stretch to speculate what an earthquake would do to the structures and subsequent change of course the mississippi.

Anonymous said...

If I recall correctly, there were reports of the Mississippi flowing NORTH during the New Madrid quake. Not for very long or its entire course, but in sections directly effected by the quake.

Dave64 said...

The Mississippi River ran backwards during that earthquake.

Tree Mike said...

Yeah, I'm a couple hundred miles east of the fault, moved here from Commiforniia, the irony.

Anonymous said...

The Corp of Engineers almost lost the dam / control structure on the Mississippi River at the Atchafalaya 8 or so years ago. Many of the towns in the Atchafalaya basin were flooded.
A failure there would also affect Baton Rouge and the chemical plants along the River near there.
John in Indy

Gerry said...

I was advised to get earthquake insurance when I moved to So.KY.
Doesn't cost much when added to my home owners policy.

Magson said...

The only reason that the Mississippi hasn't already re-routed down the Athcafalaya is becuz of the flood control dikes and whatnot. If those ever fail, then Baton Rouge, New Orleans, and a ton of other rivderine towns will all need to be relocated to a new port city somewhere down there which will probably be below sea level like NOLA is and the land is not conducive for city-building. Economic disaster doesn't even come close to describing it.

On the other side of the world, China re-routed the Yellow River trying to fight off the Japanese in 1938. It helped short term, but long term was completely disastrous, and it's now running back in its original channel. https://en.wikipedia.org/wiki/1938_Yellow_River_flood

Will said...

Peter,
the New Madrid quake in 1811 rerouted parts of the Mississippi River and other associated rivers. One section moved about 8 miles away. There was the first steamboat on the river just heading south when the quake hit. At one point the river relocated into a farmer's field and disappeared into a giant hole. They ended up running in reverse to get away from that and back to the original river routing where it had split.

"The Rift" by Walter Jon Williams contains a lot of info about the 1811 quake, most of it copies of letters written during and after the quake, that are posted at the beginning of chapters. NOT a fun time to be there!

Anonymous said...

Went to FEMA briefing once on the NMSZ (New Madrid Seismic Zone). You could tell the briefer was quite scared of this one. For those interested, there is an annual online exercise, that anyone can participate in, called "The Great Shakeout", Google it and participate if so inclined. New Madrid cutting loose is a big deal in many, many ways.

Anonymous said...

The St Francis in Arkansas used to be the Mississippi. The Mississippi at Memphis was the Ohio. Then something happened.

JaimeInTexas said...

https://www.nps.gov/vick/learn/nature/river-course-changes.htm

Re. Mississippi river

(snip)

The last major change to the river’s course in the Vicksburg area occurred in 1876. On April 26 of that year, the Mississippi River suddenly changed courses, leaving Vicksburg high and dry. The river, by its own power succeeded in cutting across the Desoto Peninsula, something which the Union troops had failed to orchestrate 13 years prior.

In 1878 work was started on a project by the U.S. Army Corp of Engineers to construct the Yazoo Diversion Canal. The Yazoo River Diversion Project took 25 years to complete, lasting from 1878 until its completion in 1903. This once again gave river traffic access to the town of Vicksburg, which in turn helped bolster the town’s economy which was drying up due to lack of a functional river port.

EricW said...

One need only look at Google Maps in satellite view to see all the various paths the Mississippi has taken over the years.

Anonymous said...

Doesn't bode well for me. I'm 6 mi west of NOLA and about 2 miles north of the Miss. River.