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Sigmetnow

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Alaska Glaciers
« on: July 27, 2013, 05:02:59 PM »
Mendenhall Glacier near Juneau, Alaska, has started to periodically flood the Mendenhall River on which the city sits.

Quote
As water builds up in the basin and seeks an outlet, it can actually lift portions of the glacier ever so slightly, and in that lift, the water finds a release. Under the vast pressure of the ice bearing down upon it, the water explodes out into the depths of Mendenhall Lake and from there into the river.

Glaciologists even have a name for the process, which is happening in many places all over the world as climates change: jokulhlaup, an Icelandic word usually translated as “glacier leap.”

http://www.nytimes.com/2013/07/23/us/alaska-looks-for-answers-in-glaciers-summer-flood-surges.html?_r=1&
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Sigmetnow

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Re: Alaska Glaciers
« Reply #1 on: August 17, 2013, 04:05:49 PM »
OK, not exactly a glacier.  But a “frozen debris lobe” threatens the Dalton Highway to Prudhoe Bay, and even the trans-Alaskan pipeline itself, above the Arctic Circle.  And it’s moving faster lately -- about an inch a day.

http://www.alaskadispatch.com/article/20130813/only-alaska-creeping-frozen-landslide-threatens-critical-highway-and-pipeline
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Sigmetnow

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Re: Alaska Glaciers
« Reply #2 on: June 27, 2015, 07:44:44 PM »
Alaska’s Glaciers Seen as Major Source of Sea Level Rise
Quote
The ice that tumbles into the ocean along Alaska’s coastline often makes for dramatic images that show one of the ravages of climate change – melting tidewater glaciers that contribute to sea level rise. But a new study finds that far more meltwater is flowing into the sea from a similar, if less frequently photographed source – inland glaciers.

Compared to their coastal counterparts, inland glaciers account for 95 percent of glacial mass loss due to climate-driven melting, a study published this month in Geophysical Research Letters shows. In fact, researchers found that Alaska’s glaciers are melting so fast that they would cover the state with a 1-foot thick layer of water every seven years.
http://www.climatecentral.org/news/alaska-glaciers-sea-level-rise-19159
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Paddy

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Re: Alaska Glaciers
« Reply #3 on: July 16, 2015, 11:28:40 PM »
Out of curiosity, how many gigatons of ice do Alaska's glaciers contain?

Tor Bejnar

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Re: Alaska Glaciers
« Reply #4 on: July 17, 2015, 12:56:27 AM »
Glaciers cover about 75,000 km2 of Alaska.
If all of Alaska's glaciers melted, sea level would rise ~ 0.05 meters (about 0.16 feet).
Ocean area=165,250,000 sq km
165,250,000 x 0.05 x 10-3 = 8,260 km-3

Results            Unit
8260000000    kilogram
8260000000000    gram
8.26E+15    milligram
8,260,000    ton
18210197710.718    pound (lb)
41300000000000    carrat
1.2747127999495E+14    grain
4.974284874552E+36    atomic mass unit

] = 0.00826 gigatonnes

if my choice of website data, internet calculators and arithmetic skills work right (without checking my work)
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Paddy

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Re: Alaska Glaciers
« Reply #5 on: July 18, 2015, 02:59:34 PM »
Thank you for that analysis!

I suppose the take home message is that Alaska is still a pretty small chunk of the total likely contribution compared to the big boys of Greenland and Antarctica...

abbottisgone

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Re: Alaska Glaciers
« Reply #6 on: April 26, 2016, 09:50:50 AM »
Thank you for that analysis!

I suppose the take home message is that Alaska is still a pretty small chunk of the total likely contribution compared to the big boys of Greenland and Antarctica...
The take home message is Glaciers are the worlds thermometers!

Complex systems are measured by indicators..
..
But I left school and grew my hair
They didn't understand
They wanted me to be respected as
A doctor or a lawyer man
But I had other plans..........

baileyrorys

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Re: Alaska Glaciers
« Reply #7 on: May 07, 2016, 12:47:16 AM »
Here's a photo of the Lamplugh Glacier at Johns Hopkins Inlet on July 22nd, 2014.

https://picasaweb.google.com/lh/photo/FIZ09Zd_a7zW5LSvuvz-a9MTjNZETYmyPJy0liipFm0?feat=directlink

solartim27

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Re: Alaska Glaciers
« Reply #8 on: July 08, 2016, 09:53:20 PM »
Lamplugh is in the news again today with a giant landslide
http://www.nytimes.com/2016/07/06/science/alaska-landslides-glaciers-melt.html?_r=2
Here is an Aqua Gif from 6/23 to 7/4

Quote
"An enormous landslide that spread rocky debris more than six miles across a glacier in southeastern Alaska last week was not the first to occur in the area, and certainly will not be the last.

The slide, first noticed by Paul Swanstrom, a sightseeing pilot, on June 28, occurred when part of a mountain gave way near Lamplugh Glacier, in Glacier Bay National Park, about 100 miles northwest of Juneau.

The slide caused seismic tremors that first registered at magnitude 2.9, , according to data from the Alaska Earthquake Center. But that magnitude was computed as if the tremors were from an earthquake. Scientists at the center later recalculated the magnitude and came up with a higher figure, 5.5."
« Last Edit: July 08, 2016, 09:59:00 PM by solartim27 »
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Tor Bejnar

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Re: Alaska Glaciers
« Reply #9 on: July 09, 2016, 05:10:48 AM »
More on this landslide from Dr. Dave Petley's July 3 Landslide Blog.

Arctic ice is healthy for children and other living things because "we cannot negotiate with the melting point of ice"

JimD

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Re: Alaska Glaciers
« Reply #10 on: July 10, 2016, 12:48:52 AM »
Wow.  To have seen that live.
We do not err because truth is difficult to see. It is visible at a glance. We err because this is more comfortable. Alexander Solzhenitsyn

How is it conceivable that all our technological progress - our very civilization - is like the axe in the hand of the pathological criminal? Albert Einstein

prokaryotes

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Re: Alaska Glaciers
« Reply #11 on: September 18, 2016, 10:53:46 PM »
A landslide 2015 caused a giant mega tsunami. After a period of heavy rains, a mountainside near Tyndall Glacier (Alaska) collapsed into a fiord of Icy Bay on October 17, 2015. The displaced water generated a 100 meter high wave that sheared alders more than 500 feet up on a hillside across from the slide.

Video


References

The giant wave of Icy Bay http://www.gi.alaska.edu/alaska-science-forum/giant-wave-icy-bay

The Tyndall Glacier landslide: images from the University of Alaska Fairbanks http://blogs.agu.org/landslideblog/2016/04/11/tyndall-glacier-landslide-2/

Related

1958 Lituya Bay megatsunami
https://en.wikipedia.org/wiki/1958_Lituya_Bay_megatsunami

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skanky

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Re: Alaska Glaciers
« Reply #12 on: November 10, 2016, 12:50:17 PM »
More on the above, again, from the same website: http://blogs.agu.org/landslideblog/2016/11/10/planet-labs-lamplugh/

johnm33

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Re: Alaska Glaciers
« Reply #13 on: November 11, 2016, 10:54:22 AM »
I'm beginning to wonder how many of these northern mountains are rubble held together by ice.

skanky

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Re: Alaska Glaciers
« Reply #14 on: December 14, 2016, 10:43:45 AM »

Aporia_filia

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Re: Alaska Glaciers
« Reply #15 on: February 09, 2017, 12:00:40 PM »
I was very surprised when a knowledgable person told me about a >500 meters wave recorded in the 50s. I could not completely believe it till I read this (some in the wiki as well);

http://geology.com/records/biggest-tsunami.shtml

Bruce Steele

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Re: Alaska Glaciers
« Reply #16 on: April 17, 2017, 08:22:27 PM »


Thirty two years ago I traveled to Prince William sound to participate in a dive fishery for a herring roe
on kelp fishery about this time of year.  A bush pilot who my wife and I hired took us on a joyride after my wife had gotten the pictures she needed for a magazine article she was writing . He took us to the base of Columbia Glacier and throttled up as he put the small plane just above the water / floating ice field.  He headed straight into a fissure and we were flying inside the Columbia glacier with ice walls a on either side of the wings. He pulled back on the stick and we exited vertically out of the glacier , did a hammerhead and shot straight back into another fissure.  We then exited the glacier back at deck level over the water/ floating ice field.
 It wasn't the craziest thing I did during that fishing season but 14 hour dives in 36 degree water are fishing stories. Maybe this all sounds like a fish story . Anyway the Columbia doesn't calf into the sound like it did back in 1984.  The Prince William Sound herring fishery has only been a small artisanal effort in the decades after the Valdez hit Bligh Rock in 1986.  I read recently a course change to avoid a iceberg field, with origins from Columbia Glacier, was causative in the tankers grounding. The collapse of the herring fishery, the collapse / retreat of the Columbia Glacier, the oil spill and the oil from the North Slope all play interactive parts in this story.

solartim27

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Re: Alaska Glaciers
« Reply #17 on: May 22, 2017, 08:37:41 AM »
Mendenhall Glacier near Juneau, Alaska, has started to periodically flood the Mendenhall River on which the city sits

Nice drone footage from the area
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solartim27

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Re: Alaska Glaciers
« Reply #18 on: August 12, 2017, 08:54:09 AM »
Insane footage from Ruth Glacier
https://www.instagram.com/p/BXgNgIFjIr1/
Quote
natgeoVideo by @renan_ozturk @sanctityofspace collection // A phenomenon of the Ruth Glacier Alaska. While filming on the glacier @freddiewilkinson noticed a couple hundred ft wide bubbling pool about a mile away from the terminus of the main glacier. The Ruth Glacier is among the thickest glaciers on earth at around 4000ft but is melting fast with the effects of climate change. We have asked a few friends but are still unsure if this is natural or abnormal. The forces seem accelerated these days as water is drawn down 'moulins' or shafts in the glacier only to emerge in such a startling high volume pool so far down valley. The inner workings are a bit of a mystery and scientific study waiting to happen but I can't help but think of it as one of my favorite places bleeding out under a warming planet. For more images of the Alaska range see @renan_ozturk @sanctityofspace. ~ Aerial DP's @camp4collective @ansonfogel @zatzworks
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Sigmetnow

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Re: Alaska Glaciers
« Reply #19 on: April 15, 2018, 04:27:13 PM »
Global warming is causing an Alaskan glacier to melt at the fastest pace in 400 years
Quote
One of the USA's tallest glaciers is melting at the fastest pace in 400 years, a new study reports.

The study said melting on Mount Hunter in Alaska’s Denali National Park can be linked mainly to rising summer temperatures in the region.

"We have not seen snow melt like this in at least four centuries,” said study lead author Dominic Winski, a glaciologist at Dartmouth College.

New ice cores taken from the top of Mt. Hunter show summers there now are least 2 to 3 degrees Fahrenheit warmer than they were during the 18th, 19th and early 20th centuries. Specifically, the ice core record shows 60 times more snow melt occurs today than did 150 years ago. ...
https://www.usatoday.com/story/news/nation/2018/04/11/global-warming-causing-alaskan-glacier-melt-fastest-pace-400-years/506549002/
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Sigmetnow

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Re: Alaska Glaciers
« Reply #20 on: April 15, 2018, 07:00:40 PM »
“Melting time lapse of the Mendenhall Glacier near Juneau. Over just 7 years. credit to James Balog @EarthVisionInst ”
https://twitter.com/ClimateHuman/status/985305766109167617

Video at the link.
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oren

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Re: Alaska Glaciers
« Reply #21 on: April 15, 2018, 08:52:02 PM »
Great video. The rate of change is scary.

solartim27

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Re: Alaska Glaciers
« Reply #22 on: July 07, 2018, 04:58:10 PM »
Another cool video
Quote
Alaska CASC (@Alaska_CASC) Tweeted:
Watch: A dramatic calving event surprised researchers at Suicide Basin, a glacier-dammed lake adjoining Mendenhall Glacier in Juneau, when a section of ice 1/5th of a mile wide separated ice in the basin from the main #glacier

https://t.co/k70hcnCs1E @NWSAPRFC @uafairbanks @USGS https://t.co/kM4BrjZcu8 https://twitter.com/Alaska_CASC/status/1012854506491502593?s=17
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ReverendMilkbone

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Re: Alaska Glaciers
« Reply #23 on: July 08, 2018, 07:40:19 PM »
Google Earth Engine shows a lot of these glaciers receding;

Mendenhall Glacier in Alaska;

https://earthengine.google.com/timelapse/#v=58.43448,-134.5559,11.03,latLng&t=1.30

Columbia Glacier in Alaska;

https://earthengine.google.com/timelapse/#v=61.14667,-146.91079,8.019,latLng&t=0.61

Barnes Ice Cap (Remnant of last ice age, also Canada but whatever) melting away...;

https://earthengine.google.com/timelapse/#v=70.0137,-74.1739,7.193,latLng&t=0.80

kassy

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Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

SteveMDFP

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Re: Alaska Glaciers
« Reply #25 on: August 17, 2019, 01:37:26 AM »
Sawyer Glacier 2012 vs 2019 pictures:
https://uk.news.yahoo.com/shocking-images-show-how-much-alaskan-glacier-has-melted-in-just-five-years-113618212.html

Very disturbing images.
Even more disturbing is the chorus of denier comments below them.

GoodeWeather

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Re: Alaska Glaciers
« Reply #26 on: August 17, 2019, 03:00:50 AM »
Sawyer Glacier 2012 vs 2019 pictures:
https://uk.news.yahoo.com/shocking-images-show-how-much-alaskan-glacier-has-melted-in-just-five-years-113618212.html

It's a horrible comparison and gives deniers more fuel.  You can clearly tell the pictures were taken from a different point of view.  The second picture was clearly taken from further away.  I would also love to know the exact date for each picture, as it appears the second picture was take at a later date in the melting season.

Tom_Mazanec

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Re: Alaska Glaciers
« Reply #27 on: September 09, 2019, 06:23:46 PM »
Navigator: Listening to the Glaciers Fall
https://www.citylab.com/newsletter-editions/2019/09/navigator-listening-glaciers-fall/597427/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+TheAtlanticCities+%28CityLab%29&utm_content=FeedBurner
Quote
“White Thunder” is the name some locals have for it—the sound ice makes as it’s melting, breaking into pieces, and retreating. We squinted and strained, bodies alert, waiting for something to happen.

When it comes to on-the-nose symbols of climate change (and an individual’s complicity in it), this scene is up there. My family and I had traveled to Alaska’s Kenai Fjords National Park for a summer vacation. Together, we had flown, driven, and boated more than 7,000 miles to get to a land that’s often described as “untouched.” And there we were, under the sun of one of Alaska’s hottest summers in recent memory, staring at something that looked so permanent, breathlessly waiting to see it change.

vox_mundi

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Re: Alaska Glaciers
« Reply #28 on: December 14, 2019, 10:42:27 PM »
See How an Alaskan Glacier has Shrunk Over Time
https://www.sciencenews.org/article/see-how-alaska-columbia-glacier-has-shrunk-over-time



Alaska’s Columbia glacier began rapidly retreating around 1980, and its leading edge has moved more than 20 kilometers inland. These images, captured by the joint NASA / U.S. Geological Survey Landsat satellites, were stitched together into a video to show the glacier’s dynamic evolution from 1972 to 2019. Video: Mark Fahnestock / University of Alaska Fairbanks
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vox_mundi

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Re: Alaska Glaciers
« Reply #29 on: June 27, 2020, 10:29:22 PM »
More Fragments From 1952 Crash In Alaska Found In Glacier
https://phys.org/news/2020-06-fragments-alaska-glacier.html


https://glacierhub.org/tag/c-124-globemaster/

A lucky Buddha figurine, a flight suit, several 3-cent stamps, a crumpled 1952 Mass schedule for St. Patrick's Church in Washington, D.C., and 480 bags containing individual human remains.

Those were among the items recovered this month from Alaska's Colony Glacier, where an annual somber search continues for human remains and debris after a military plane crashed 67 years ago, officials said Friday.

The goal is to identify and return remains from everyone onboard the C-124 Globemaster, which smashed into Mount Gannett north of Anchorage on Nov. 22, 1952, killing all 41 passengers and 11 crew members, military officials said Friday at a news conference at Joint Base Elmendorf-Richardson in Anchorage.

The remains of those killed weren’t retrieved at the time, and the plane and all it held slowly fell to the bottom of the mountain, where it eventually became part of Colony Glacier.

... The crash was virtually forgotten until a military training mission spotted a yellow life raft on the glacier. Efforts began in 2012 to scour the glacier to see what else may have churned up, including human remains and other debris.

Now, the race is on to identify as many service members as possible before the glacier dumps the wreckage into Lake George, which will become a final resting place for everything that isn't saved. ... They might have only several more years of searching the glacier before the debris field calves into the lake.

The last area they found remains this year was about 656 feet (200 meters) from the toe of the glacier, where the ice falls into the lake.

Using a back-of-the-envelope calculation, McNabb said the plane traveled 23 kilometers along the flowpath. McNabb calculated that the average surface velocity would have been about 1.5 meters per day.

https://en.m.wikipedia.org/wiki/1952_Mount_Gannett_C-124_crash



The reappearance of a long-lost body in the ice isn’t a new thing and will likely become more common as global climate change melts more ice, revealing the frozen corpses of people thought to be missing forever.
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― anonymous

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

vox_mundi

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Re: Alaska Glaciers
« Reply #30 on: September 09, 2020, 12:07:06 PM »

Fly Above Alaskan Glaciers in 360°
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― anonymous

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

vox_mundi

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Re: Alaska Glaciers
« Reply #31 on: March 18, 2021, 10:35:45 PM »
Melting Glaciers Contribute to Alaska Earthquakes
https://phys.org/news/2021-03-glaciers-contribute-alaska-earthquakes.html



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.

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.



Chris Rollins et al, Stress Promotion of the 1958 M w ∼7.8 Fairweather Fault Earthquake and Others in Southeast Alaska by Glacial Isostatic Adjustment and Inter‐earthquake Stress Transfer, Journal of Geophysical Research: Solid Earth (2020)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JB020411
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― anonymous

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

Brigantine

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Re: Alaska Glaciers
« Reply #32 on: March 20, 2021, 05:03:14 AM »
OK, not exactly a glacier.  But a “frozen debris lobe” threatens the Dalton Highway to Prudhoe Bay, and even the trans-Alaskan pipeline itself, above the Arctic Circle.  And it’s moving faster lately -- about an inch a day.

Update on this - a new road was built 110m further away, and the frozen debris lobe is on track to hit the old section of highway (currently 6.1m away) this autumn. It's a natural experiment - what happens when an FDL meets a highway?

Webcam and time-lapse: https://fdlalaska.org/

Sebastian Jones

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Re: Alaska Glaciers
« Reply #33 on: April 09, 2021, 08:51:31 PM »
This one is definitely about a glacier.
The Muldrow Glacier flows from Denali and is mostly very quiet, but about every half century, it undergoes a surge event.
The last one was in 1956/57.
"The 1956/57 surge caused dramatic changes to Muldrow Glacier and its tributaries. About 3.3 km3 of Ice was redistributed from the upper and middle portions of the glacier to the toe (Post 1960). This caused lowering of the ice surface by 170 m in the upper parts of the glacier; lateral moraines were stranded and the lowering of the main trunk left some of the smaller glacier tributaries hanging by as much as 61 m (Post 1960). In contrast, the toe of the glacier gained ice, causing the surface to rise and the toe to advance forward forming a wall of ice 200 feet tall (Millett 1960)."
A local pilot recently noticed that it is beginning its next surge and Denali Park and USGS scientists have deployed numerous sensors and cameras to monitor the event.
I expect that this data will give us fascinating views of this spectacular event. Covid permitting, it will be worth a visit this summer.
Peak advances of 10-20m/day will be easily visible (and audible).
https://www.nps.gov/articles/dena-muldrow.htm

gerontocrat

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Re: Alaska Glaciers
« Reply #34 on: April 09, 2021, 09:23:16 PM »
Hullo Sebastian

got nowhere with your link so

https://www.nationalparkstraveler.org/2021/04/denalis-muldrow-glacier-currently-experiencing-historic-surge-event

The Muldrow Glacier at Denali National Park recently began "surging" downhill. This shot by pilot Chris Palms is looking up the main stem of the glacier with Denali in the top left, McGonagall Pass in the upper right and the Traleika Glacier tributary coming in from top left. Sheer lines of broken ice and abundant crevasses are visible/ Chris Palms via NPS


Map of the Muldrow Glacier and surrounding area. Imagery is Alaska SDMI SPOT 5 Mosaic Dataset (2010-2013), glacier outlines are from Randolph Glacier Inventory/NPS

click the images to enlarge
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The Walrus

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Re: Alaska Glaciers
« Reply #35 on: April 09, 2021, 09:24:08 PM »
This one is definitely about a glacier.
The Muldrow Glacier flows from Denali and is mostly very quiet, but about every half century, it undergoes a surge event.
The last one was in 1956/57.
"The 1956/57 surge caused dramatic changes to Muldrow Glacier and its tributaries. About 3.3 km3 of Ice was redistributed from the upper and middle portions of the glacier to the toe (Post 1960). This caused lowering of the ice surface by 170 m in the upper parts of the glacier; lateral moraines were stranded and the lowering of the main trunk left some of the smaller glacier tributaries hanging by as much as 61 m (Post 1960). In contrast, the toe of the glacier gained ice, causing the surface to rise and the toe to advance forward forming a wall of ice 200 feet tall (Millett 1960)."
A local pilot recently noticed that it is beginning its next surge and Denali Park and USGS scientists have deployed numerous sensors and cameras to monitor the event.
I expect that this data will give us fascinating views of this spectacular event. Covid permitting, it will be worth a visit this summer.
Peak advances of 10-20m/day will be easily visible (and audible).
https://www.nps.gov/articles/dena-muldrow.htm

Yes, this has gotten quite a few glaciologists very excited, as this is happening for the first time during their lifetime.

vox_mundi

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Re: Alaska Glaciers
« Reply #36 on: April 13, 2021, 01:22:51 AM »
The National Park Service has a surge page now ...

https://www.nps.gov/articles/dena-muldrow.htm

Denali Park glacier surging 65 feet a day, threatening summit route

... Before the surge, the ice was moving between 3 and 11 inches per day. Now it's moving 30 to 60 feet per day, according to satellite image analysis.

During the last surge event in 1956-57, the glacier moved over 4 miles in a period of months.

"It's gone from basically a very smooth, level ice surface to a totally impassable crevassed area," Adema said.



... “[There’s the] potential for a very intense outburst flood. There’s just masses of water trapped under that glacier, to lubricate that surface to the extent where it can surge at this rate,” he said. “The reason the surge ends is because that trapped water finds a path out.”
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morganism

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Re: Alaska Glaciers
« Reply #37 on: June 19, 2021, 03:28:45 AM »
Ten Minutes in Lituya Bay

A remote bay in Alaska is home to an odd and occasionally catastrophic geology. In 1958, a handful of people experienced this firsthand.

" At around 6:20am local time, the men reported hearing a loud, continuous roar begin to emanate from the inland end of the long, narrow bay. They squinted toward the source of the sound, but it was still dark out. This confusing cacophony continued for around thirty minutes before the men sighted the cause of the great white noise: a wave about fifty feet high on a collision course with their vessel. It was strange for a large wave to be coming from the direction of land rather than the open ocean, but the men had no time to contemplate such details. Without further ado they pulled anchor and started the engine. The fishing boat lacked the speed to escape the bay before the wave arrived, but they thought they might be able to take cover behind Cenotaph Island."

"Bill Swanson’s bunk tilted, dumping him onto the deck. When he looked outside, the water around his boat was in a state of severe agitation. In the distance he could see the towering mountains that stood at the inland end of the bay, their peaks shaking. He also thought he saw the distant Lituya Glacier tossed up into the air. “I know you can’t ordinarily see that glacier from where I was anchored,” he later told Alaska Sportsman magazine. “People shake their head when I tell them I saw it that night. I can’t help it if they don’t believe me but I know what I saw that night.”"

After a minute or so of apparent calm, a crash described as “deafening” rattled the atmosphere. One of the unnamed mountain peaks that stood at the inland end of Lituya Bay had broken off, dropping ninety million tons of rock into the water with the force equivalent to a meteor strike. The resulting impact shook loose other rocks on the slopes, and chunks of adjacent glaciers, and these plunged into the water practically all at once. Millions of cubic yards of displaced water heaved upward and formed a wave traveling outward at about 110 miles per hour (180 km/h).

https://www.damninteresting.com/ten-minutes-in-lituya-bay/

morganism

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Tsunami warning issued for parts of Alaska after 8.2 quake
« Reply #38 on: July 29, 2021, 11:17:19 AM »
Had a post that was pulled, that i think was near here, where the "mountains jumped".

Tsunami warning issued for parts of Alaska after 8.2 quake

https://abcnews.go.com/US/wireStory/tsunami-watch-issued-hawaii-82m-quake-hits-alaska-79134509

The U.S. Geological Survey said the quake was magnitude 8.2 and hit 56 miles (91 kilometers) east southeast of Perryville, Alaska at about 8:15 p.m. Wednesday. The quake was about 29 miles (46 kilometers) below the surface of the ocean, according to USGS.

meddoc

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Re: Alaska Glaciers
« Reply #39 on: July 29, 2021, 11:26:41 AM »
M 8.2 Earthquake hit SE of Alaskan Peninsula...

Isostatic Rebound hello.
Expect WA, OR, CA be hit by M 5-7.0
Also, on the global Antipode (Indian Ocean) another M7- 8.0ish

Brigantine

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Re: Alaska Glaciers
« Reply #40 on: July 29, 2021, 12:28:10 PM »
M 8.2 Earthquake hit SE of Alaskan Peninsula...

Isostatic Rebound hello.
Expect WA, OR, CA be hit by M 5-7.0
Also, on the global Antipode (Indian Ocean) another M7- 8.0ish
Pacific ring of fire / subduction zone. A cool event, but by no means unexplained.
location: right by M8.3 1938
depth 32.2km

What's the grounds to draw a connection to isostatic rebound?
And care to constrain your predictions in terms of timeframe and location?

RoxTheGeologist

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Re: Alaska Glaciers
« Reply #41 on: July 30, 2021, 12:15:55 AM »

Looks like a standard subduction zone quake to me, particularly at that depth. 

FishOutofWater

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Re: Alaska Glaciers
« Reply #42 on: July 30, 2021, 02:37:15 AM »
Yes, Rox, it was a very typical subduction zone earthquake with a typical focal mechanism of underthrusting of the oceanic plate. The good news is that the seafloor did not move enough to generate more than a local small tsunami with a maximum deviation from normal tides of .66m at Sand Point, Alaska.

Some of the earlier comments are not based on science.

Rod

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Re: Alaska Glaciers
« Reply #43 on: July 30, 2021, 03:38:54 AM »

Some of the earlier comments are not based on science.

In fairness to whatever was posted above (which seems to have been removed) I was up when it hit.  There was a lot of confusion, and even the National Weather Service and Mets with large audiences were  talking about tsunamis hitting all the way to Hawaii and Los Angeles within 5 to 6 hours.

The mood in Alaska was panic. They had less than an hour if a tsunami was to hit.  Warning sirens were blasting and people were evacuating all the way to Anchorage.

It is easy to look back after the dust has settled and say those actions were not warranted.  But, in the heat of the moment, when people’s lives are on the line it is better to be safe than sorry.
« Last Edit: July 30, 2021, 03:47:02 AM by Rod »

CraigsIsland

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Re: Alaska Glaciers
« Reply #44 on: July 30, 2021, 07:54:20 AM »

Some of the earlier comments are not based on science.

In fairness to whatever was posted above (which seems to have been removed) I was up when it hit.  There was a lot of confusion, and even the National Weather Service and Mets with large audiences were  talking about tsunamis hitting all the way to Hawaii and Los Angeles within 5 to 6 hours.

The mood in Alaska was panic. They had less than an hour if a tsunami was to hit.  Warning sirens were blasting and people were evacuating all the way to Anchorage.

It is easy to look back after the dust has settled and say those actions were not warranted.  But, in the heat of the moment, when people’s lives are on the line it is better to be safe than sorry.

Hard agree. I woke up this morning to the post-dust settle and I can see why outsiders may think it was a overkill response. It was not. Better safe than sorry. And it provides valuable data for training and correcting emergency response.

RoxTheGeologist

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Re: Alaska Glaciers
« Reply #45 on: July 30, 2021, 08:59:28 PM »
Yes, Rox, it was a very typical subduction zone earthquake with a typical focal mechanism of underthrusting of the oceanic plate. The good news is that the seafloor did not move enough to generate more than a local small tsunami with a maximum deviation from normal tides of .66m at Sand Point, Alaska.

Some of the earlier comments are not based on science.

Exactly - subduction zone earthquakes can displace a huge volume of seafloor if the fault movement is steep enough - the 2005 Indonesia M8.6 earthquake is a good (and terrifying) example.

oren

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Re: Alaska Glaciers
« Reply #46 on: July 31, 2021, 03:21:17 AM »
This happens to be my fault, as I have moved a couple of posts here rather than have new threads popping up over a one time event, and as I cannot move posts beyond the Cryosphere subsection. However, this thread is mainly about Alaskan glaciers, and due to history also discusses Alaskan earthquakes after a fashion, in any case let's not get too far with the pure earthquake discussions.

kassy

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Re: Alaska Glaciers
« Reply #47 on: September 18, 2021, 11:27:10 AM »
Melting glacier reveals forest entombed by ice 1,300 years ago in southern Alaska

“The log pictured here might at first seem to be just another piece of driftwood coming down Exit Creek, but it tells a much more interesting story,” the park wrote in a Sept. 8 Facebook post.

“This section of wood was once part of an ancient forest that was entombed by Exit Glacier around 1300 years ago, sometime between AD 641-771. As the glacier has continued to melt back these pieces of ... wood are slowly being uncovered.”

Scientists refer to such debris as interstadial wood, from forests that “thrived prior to the last ice age.” The forests grew over decades-long periods “between glacial advances, when local conditions were temporarily conducive to forest growth,” NPS officials say.

...

Kenai Fjords National Park, created in 1980, describes itself as “a land where the ice age lingers.”

“Nearly 40 glaciers flow from the Harding Icefield, Kenai Fjords’ crowning feature. Wildlife thrives in icy waters and lush forests around this vast expanse of ice,” the park says. “Today, shrinking glaciers bear witness to the effects of our changing climate.”

Exit Glacier has been receding since the 1800s at “roughly 3 feet a year, based on soil and tree-ring analysis,” according to a report in the Christian Science Monitor. “Now the glacier is retreating faster, much faster, in winter and summer,” the site reported.

The glacier is now receding nearly 300 feet annually, exposing sections of land that were covered for centuries, the NPS reports.

https://www.kansascity.com/news/nation-world/national/article254309353.html

Can we get tree rings from these logs? It does not look that good but maybe it looks better on the inside?
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