Claim: Melting glaciers contribute to Alaska earthquakes

UNIVERSITY OF ALASKA FAIRBANKS

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IMAGE: GLACIERS SUCH AS THE YAKUTAT IN SOUTHEAST ALASKA, SHOWN HERE, HAVE BEEN MELTING SINCE THE END OF THE LITTLE ICE AGE, INFLUENCING EARTHQUAKES IN THE REGION. view more CREDIT: PHOTO BY SAM HERREID

In 1958, a magnitude 7.8 earthquake triggered a rockslide into Southeast Alaska’s Lituya Bay, creating a tsunami that ran 1,700 feet up a mountainside before racing out to sea.

Researchers now think the region’s widespread loss of glacier ice helped set the stage for the quake.

In a recently published research article, scientists with the University of Alaska Fairbanks Geophysical Institute found that ice loss near Glacier Bay National Park has influenced the timing and location of earthquakes with a magnitude of 5.0 or greater in the area during the past century.

Scientists have known for decades that melting glaciers have caused earthquakes in otherwise tectonically stable regions, such as Canada’s interior and Scandinavia. In Alaska, this pattern has been harder to detect, as earthquakes are common in the southern part of the state.

Alaska has some of the world’s largest glaciers, which can be thousands of feet thick and cover hundreds of square miles. The ice’s weight causes the land beneath it to sink, and, when a glacier melts, the ground springs back like a sponge.

“There are two components to the uplift,” said Chris Rollins, the study’s lead author who conducted the research while at the Geophysical Institute. “There’s what’s called the ‘elastic effect,’ which is when the earth instantly springs back up after an ice mass is removed. Then there’s the prolonged effect from the mantle flowing back upwards under the vacated space.”

In the study, researchers link the expanding movement of the mantle with large earthquakes across Southeast Alaska, where glaciers have been melting for over 200 years. More than 1,200 cubic miles of ice have been lost.

Southern Alaska sits at the boundary between the continental North American plate and the Pacific Plate. They grind past each other at about two inches per year — roughly twice the rate of the San Andreas fault in California — resulting in frequent earthquakes.

The disappearance of glaciers, however, has also caused Southeast Alaska’s land to rise at about 1.5 inches per year.

Rollins ran models of earth movement and ice loss since 1770, finding a subtle but unmistakable correlation between earthquakes and earth rebound.

When they combined their maps of ice loss and shear stress with seismic records back to 1920, they found that most large quakes were correlated with the stress from long-term earth rebound.

Unexpectedly, the greatest amount of stress from ice loss occurred near the exact epicenter of the 1958 quake that caused the Lituya Bay tsunami.

While the melting of glaciers is not the direct cause of earthquakes, it likely modulates both the timing and severity of seismic events.

When the earth rebounds following a glacier’s retreat, it does so much like bread rising in an oven, spreading in all directions. This effectively unclamps strike-slip faults, such as the Fairweather in Southeast Alaska, and makes it easier for the two sides to slip past one another.

In the case of the 1958 quake, the postglacial rebound torqued the crust around the fault in a way that increased stress near the epicenter as well. Both this and the unclamping effect brought the fault closer to failure.

“The movement of plates is the main driver of seismicity, uplift and deformation in the area,” said Rollins. “But postglacial rebound adds to it, sort of like the de-icing on the cake. It makes it more likely for faults that are in the red zone to hit their stress limit and slip in an earthquake.”

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From EurekAlert!

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March 19, 2021 2:04 am

Nature at work.

mkelly
Reply to  Philip Mulholland
March 19, 2021 9:07 am

There were survivors of this. Father and son on a fishing boat.

https://www.dailymotion.com/video/x7qc51v

Ruleo
Reply to  mkelly
March 19, 2021 7:02 pm

???

March 19, 2021 2:33 am

Since somebody on this site gave me the word ‘lithosphere’, I can shorten my comment to:
“Oh, wow, somebody acknowledges weather patterns happen in the lithosphere! What a friggin’ surprise!”

Editor
March 19, 2021 2:59 am

Basically, they’re saying global warming contributes to earthquakes.

Oh goodie! Shake and bake.

Regards,
Bob

H.R.
Reply to  Bob Tisdale
March 19, 2021 4:01 am

“And I helped.”

(From the original Shake ‘n Bake commercials.)

Good one, Bob. 👍

Editor
Reply to  H.R.
March 19, 2021 4:36 am

Thanks for the, “And I helped.”, H.R.

That made me laugh.

Regards,
Bob

Joseph Zorzin
Reply to  Bob Tisdale
March 19, 2021 6:27 am

Oh, of course, GW causes all unwanted events- it’s the new Satan. We must all follow the new religion to defeat the new Satan.

James Snook
Reply to  Bob Tisdale
March 19, 2021 7:35 am

Yup, and for two hundred years 🤡

Ron Long
March 19, 2021 3:07 am

Total nonsense. The 1958 Lituya Bay earthquake was produced when the Fairweather Fault, a strike-slip fault, moved 20 feet in a right-lateral sense. The epicenter of the fault movement was at 35 kilometers (22 miles) depth. This fault is actually the boundary between the North American Plate and the Pacific Plate (think San Andreas and associates). Try to imagine two giant plates moving past each other and an epicenter of the adjustment movement 35 kilometers deep being influenced by some post-glacier rebound at the surface. Association is not causation. The only unusual thing about this earthquake is dislodging a lot of loose rock (talus) that slid into the bay and produced a large splash, which was the origin of the tsunami.

Peta of Newark
Reply to  Ron Long
March 19, 2021 4:26 am

Exactly Ron
They’ve got Cause & Effect the wrong way round

Don’t we all know, if you find yourself wanting rid of a large piece of ice, the very first thing you do is hit it with a hammer
The resulting smaller pieces melt so much faster and/or slide away down a hillside if you’re on one.
(If “large lump of ice on a hillside” don’t define ‘glacier’ – what does?)

That is precisely what the earthquake does, crunches up the ice and THEN it melts faster/easier, then flows away carrying the small(er) bits in the flow or actually making up the flow.
IOW: Earthquakes trigger avalanches = knowledge that’s as ‘Old As The Hills’

Truly weird things happen inside computers (their programmers heads)

Last edited 26 days ago by Peta of Newark
Dennis G Sandberg
Reply to  Peta of Newark
March 19, 2021 9:30 am

Exactly, libs always confuse cause and effect. It’s the way their minds work. They can’t help it, they were born with the affliction (IMHO). Understanding that makes it easier for me to love and enjoy my liberal friends.

Jeff Alberts
Reply to  Ron Long
March 19, 2021 9:20 am

Isn’t that the one where the bay drained quickly, but briefly?

As for the uplift causing quakes, wouldn’t the opposite also be true? If glaciers were advancing, the compression could also cause quakes?

Hey Griff. If glaciers were advancing, would that be a good thing or a bad thing?

fretslider
March 19, 2021 3:50 am

Make bold claim here

Back it up with ‘model’ here

So, just how much of a correlation is there? To my mind a subtle correlation doesn’t sound that strong at all, it sounds, well, tenuous at most.

This seems more than appropriate… Thin Ice

https://open.spotify.com/track/2SP91E5A3qQTrem8XKLH02?si=97384520332646a9

Willis has his studies and I have a studio.

Last edited 26 days ago by fretslider
Editor
March 19, 2021 4:31 am

Alaska glaciers have been retreating since since the 18thC

https://notalotofpeopleknowthat.wordpress.com/2019/01/10/michael-portillos-alaskan-glacier/

griff
Reply to  Paul Homewood
March 19, 2021 5:21 am

But now they are retreating more quickly, with a sharp increase in the rate since 1990 (which is true of almost all glaciers worldwide)

Reply to  griff
March 19, 2021 6:12 am

45% of the glacial retreat occurred before 1900, when atmospheric CO2 was still below 300 ppm. By 1950, 75% of the glacial retreat had occurred. Only 25% of the glacial retreat has occurred since humans allegedly became the primary drivers of climate change.

Only 10% of the glacial retreat has occurred since this was the climate crisis du jour…

At the time of “The Ice Age Cometh” (1975), 90% of the glacial retreat had already occurred.

The ice age is coming, the sun’s zooming in
Engines stop running, the wheat is growing thin
A nuclear era, but I have no fear
’Cause London is drowning, and I live by the river

— The Clash “London Calling,” released in 1979

https://youtu.be/EfK-WX2pa8c

MarkW
Reply to  David Middleton
March 19, 2021 8:44 am

How dare you use data in a religious debate?
And I don’t mean that Data.

Erik Magnuson
Reply to  griff
March 19, 2021 8:15 am

Griff,

The National Park System brochure for Glacier Bay states that what is now the bay was dry land in 1600! This strongly implies that the retreat of the glaciers is being caused by the local climate returning to normal.

Jeff Alberts
Reply to  Erik Magnuson
March 19, 2021 9:25 am

Actually “normal” depends on the timeline. “Normal” for the last several hundred thousand years is mile-thick ice for that area. We’re in an interglacial, which is outside the norm.

On the outer Barcoo
Reply to  Jeff Alberts
March 19, 2021 2:41 pm

Alaska has not been covered by a continental icesheet during the current Ice Age which began about 2.6 million years ago. That is why it has been an animal refugia and the gateway to human migration from Asia into the Americas. Mountain glaciers come and go, particularly during interglacial periods (such as the one that start about 10,000 years ago).

Jeff Alberts
Reply to  On the outer Barcoo
March 19, 2021 8:27 pm

Certainly some of it was, the rest seems to have been dry tundra and polar desert.

comment image


Dave Andrews
Reply to  griff
March 19, 2021 10:17 am

But Griff they say that glaciers in Southeast Alaska have been melting for over 200 years and we also know that glaciers in the Alps began retreating in the 1860s and that the Athabasca glacier in Canada was retreating before the end of the 19th century. All these retreats began well before CO2 emissions could have played an y part.

John Tillman
Reply to  griff
March 19, 2021 11:20 am

Many glaciers are advancing, including Alaska’s Hubbard and others in North America, but also in South America, Asia, Europe, Greenland, Antarctica and New Zealand. Dunno about Africa.

Doonman
Reply to  griff
March 19, 2021 11:32 am

Griff’s claim is that all ice loss worldwide is accelerating. We will all wait hopelessly once again as he armwaves while presenting no data to back up his claims.

But then David Middleton presents the results of several studies that show Griff’s claims to be suspect.

Will Griff now change his beliefs and retract his claims? It’s highly doubtful because Griff is not interested in any observation that will change his religion.

As the noted economist John Maynard Keynes once said “When the facts change, I change my mind – what do you do, sir?”

Last edited 26 days ago by Doonman
Pat from kerbob
Reply to  griff
March 19, 2021 7:34 pm

As always
Clown based internetting

commieBob
March 19, 2021 4:40 am

There is some evidence that postglacial rebound can result in earthquakes. link Apparently that doesn’t happen a lot. The biggest postglacial rebound is in the area of Churchill Manitoba. I’ve never heard of an earthquake there.

Postglacial rebound is a slow process, taking thousands of years. Also, the modern melting of glaciers is puny compared with the loss at the beginning of the Holocene.

It seems that, if there’s going to be an earthquake anyway, a melting glacier may be the straw that broke the camel’s back but I wonder if it’s honest to call it the cause.

Reply to  commieBob
March 19, 2021 5:25 am

Scandinavia, here Sweden and Finland, isn’t known for earthquakes but it’s rebound is several mm / year
comment image

Source

Earthling2
Reply to  Krishna Gans
March 19, 2021 9:28 am

I wonder if St. Greta realizes that much of northerly Scandinavia has sea levels dropping, and if she understands why?

Larry in Texas
Reply to  Earthling2
March 19, 2021 10:55 am

I can make the same observation about the areas surrounding the Great Lakes. About twenty years ago or so, scientists were expressing concern about lake levels dropping in places like Lake Superior and Lake Michigan. Turns out there was considerable evidence that land rebound in those areas was still taking place, even after around 13,000 years. And having lived in that area for 22 years, with some of my relatives still living there, I haven’t noticed any major earthquakes in that area at all (especially of a 7.8 magnitude).

Yes, geological processes are very slow things, with a lot of intervening events that occur so that it’s a bit of a stretch to make such a facile correlation here.

Ed Zuiderwijk
Reply to  Krishna Gans
March 19, 2021 9:35 am

Why is the rebound centred on the Botnian Gulf when the ice sheets extended much much farther east? Wouldn’t one expect that for instance the Kola peninsula would be as much affacted as the north of Sweden or even more?

MarkW
Reply to  Ed Zuiderwijk
March 19, 2021 9:53 am

I would expect maximum uplift to be in those areas where the glaciers were the thickest. There’s also issues with the thickness of the crust. A mile thick ice sheet where the crust is thin, might cause more depression than a two mile thick ice sheet in a place where the crust is thicker and stronger.

Giordano Milton
March 19, 2021 4:51 am

Glacial rebound happens after every ice age and lasts for a very long time. And then it repeats.

Reply to  Giordano Milton
March 19, 2021 6:00 am

So. glacial rebound can cause earthquakes? Most quakes are from tectonic plate movement. Mt. Everest is still being pushed upward.

Editor
March 19, 2021 6:06 am

Post glacial rebound (PGR) does induce seismicity. It’s why New England has lots of earthquakes… They’re just very tiny, nonpalpable earthquakes.

Ed Zuiderwijk
March 19, 2021 6:49 am

Melting glaciers causing earthquakes? Then growing glaciers will cause earthquakes too. Hence if an earthquake has happened you don’t know from that fact alone whether the glacier responsible, if there’s indeed one, was growing or melting. Ai, we’re stuck!

Coach Springer
March 19, 2021 6:54 am

While the [melting of glaciers] is not the direct cause of [earthquakes], it likely …” Said every “study” on anything ever. Enough wiggle room to steer a semi full of wild guesses through. But the models based on perceived correlation and unproven theory are science?

Bob in Calgary
March 19, 2021 7:29 am

“models…found a subtle but unmistakable correlation” QED

Olen
March 19, 2021 7:46 am

There are earthquakes and there are earthquakes but no matter the cause man caused the cause. Even the wobble of the earth, the polar motion was caused by man probably about the time Eve took her first bite.

MarkW
March 19, 2021 8:42 am

They found the correlation in the model.
But apparently they haven’t been able to find any correlation in real world data. Otherwise they would lead with that instead.

TonyG
Reply to  MarkW
March 19, 2021 9:58 am

It seems they don’t even bother to LOOK at real world data anymore. Models are all that’s needed to determine reality.

Steve Z
March 19, 2021 10:24 am

How much of the melting of the glaciers prior to 1958 was due to additional CO2 in the air? They didn’t have the observation station at Mauna Loa back then.

There was a major earthquake in Magna, Utah (just south of the Great Salt Lake) a year ago yesterday, but there were no glaciers there for at least the previous 6 years, and probably much longer. There’s usually about 2 to 3 feet of snow on the nearby mountains in winter, but it melts every summer. So what caused the earth to quake last year?

DHR
Reply to  Steve Z
March 19, 2021 1:59 pm

Please consult your local seismologist. There have been four earthquakes around Salt Lake City in the past 2 days! They are quite common in the area.

Paul of Alexandria
March 19, 2021 10:30 am

Ok, so how many people are now going to argue that we should promote glacial growth in order to prevent earthquakes?

March 19, 2021 5:14 pm

They are looking far to short in time. A much better defined caldera outbreak took place along the Alaska Peninsula following the end of the last Ice Age. These include Fisher, Aniakchak, Veniamanof, Kaguyak, Emmons Lake (Pavlof). There are others down the AK Penninsuoa, but you get the idea . Cheers –

Pat from kerbob
March 19, 2021 7:29 pm

Excellent
Every location that springs up from loss of glacier weight is no longer in danger of “accelerated sea level rise”, and as it warms it becomes farmland

Winning every way

Walter Sobchak
March 20, 2021 8:57 am

“Rollins ran models of earth movement and ice loss since 1770,”

Mathematical onanism. Better stop it or you’ll go blind.

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