Jump to content
  • Sign Up
×
×
  • Create New...

[NASA] Tracy Arm’s Post-Tsunami Landscape

SpaceMan

By SpaceMan,
in World News

 Share

Recommended Posts

  • Diamond Member
SpaceMan Hunter

SpaceMan 0

Posted
  • Diamond Member
Posted
Earth Observatory
  1. This is the hidden content, please
  2. This is the hidden content, please
  3. Tracy Arm’s Post-Tsunami…
 


This is the hidden content, please

This is the hidden content, please

July 26, 2025
August 19, 2025

This is the hidden content, please
NASA Earth Observatory/Michala Garrison

This is the hidden content, please
NASA Earth Observatory/Michala Garrison
July 26, 2025August 19, 2025

This is the hidden content, please
NASA Earth Observatory/Michala Garrison
This is the hidden content, please
NASA Earth Observatory/Michala Garrison

July 26, 2025

August 19, 2025


CurtainToggle2-Up

Image Details

The shores of Tracy Arm, a fjord in southeast Alaska, are stripped of vegetation following a landslide and tsunami that occurred on August 10, 2025. The
This is the hidden content, please
(Operational Land Imager) on
This is the hidden content, please
and
This is the hidden content, please
show the area in the weeks before and after the event, respectively.

Carved over millennia by the pressure and motion of glacial ice, the valley walls cradling the Tracy Arm fjord in southeast Alaska continue to be reshaped. In summer 2025, following the rapid retreat of South Sawyer Glacier, a large landslide sent rock careening into the fjord, altering the wider landscape in a matter of minutes.

The slide culminated on the morning of August 10, 2025, when at least 64 million cubic meters of rock slid downslope. Material entering the fjord induced a tsunami that stripped trees and other vegetation from the opposing fjord wall up to 1,578 feet (481 meters) above sea level. While this peak was the highest “runup” reached by the tsunami, shores and islands down the fjord also saw substantial destruction.

NASA-USGS Landsat satellites captured these images on July 26 (left) and August 19 (right), before and after the event, respectively. “The bright landslide scar on the north side of the fjord is striking, as is the ‘bathtub’ ring around the fjord showing the areas where the forest was leveled by the tsunami,” said Dan Shugar, a geomorphologist at the University of Calgary.

Note that Sawyer Island, about 6 miles (9 kilometers) from the landslide, also turned from green to brown. Only a few trees still stood at the island’s higher elevations.

This is the hidden content, please
The landslide scar and the zone where vegetation was stripped by the resulting tsunami are both visible in this aerial photo of Tracy Arm and South Sawyer Glacier, captured on August 13, 2025.
U.S. Geological Survey/John Lyons

In the months following the slide, Shugar and colleagues combined satellite, airborne, and

This is the hidden content, please
with eyewitness reports and simulations to build a more complete picture of how the event unfolded. Their analysis, detailing the event from its lead-up through its aftermath, was published May 6, 2026, in the journal
This is the hidden content, please
.

In addition to the details outlined above, the researchers showed that water continued to slosh around the fjord—a phenomenon known as a “

This is the hidden content, please
”—for more than a day. Both the landslide and seiche produced seismic signals detected around the world, the former equivalent to a magnitude 5.4 earthquake.

The Landsat images also reveal significant retreat at the front of South Sawyer Glacier in less than a month. “Part of that occurred between the date of the first image and the date of the landslide,” Shugar said. “But part of it is from the landslide itself, which broke off a big chunk of the terminus of South Sawyer Glacier, resulting in a slurry of icebergs in the fjord.”

The exact mechanisms that caused the landslide remain uncertain and could have involved a combination of factors. Rainfall, which was moderate prior to the event, and the rapid retreat of glaciers can both destabilize a slope. What is clear, however, is that the glacier’s retreat exposed a new area of open water, leaving it vulnerable to a landscape-reorganizing tsunami. 

This is the hidden content, please
Tracy Arm and other nearby fjords connect with Stephens Passage, a major waterway in southeast Alaska, visible in this image captured on August 19, 2025, by the
This is the hidden content, please
(Operational Land Imager) on
This is the hidden content, please
.
NASA Earth Observatory/Michala Garrison

No one was injured in the event, though it did catch some by surprise. Kayakers camping on Harbor Island near the fjord’s mouth had their

This is the hidden content, please
, and passengers aboard a small cruise vessel in neighboring Endicott Arm reported swings in water levels and a strong current associated with the tsunami. Brentwood Higman of Ground Truth Alaska, a co-author of the paper, noted that a glacier’s shift from relative stability to renewed retreat, visible in satellite images, could serve as an important indicator that an area has become more susceptible to landslide and tsunami hazards.

NASA Earth Observatory images by Michala Garrison, using Landsat data from the 

This is the hidden content, please
. Photograph by John Lyons/U.S. Geological Survey. Story by Kathryn Hansen.

Downloads

This is the hidden content, please

July 26, 2025

JPEG (17.40 MB)

This is the hidden content, please

August 19, 2025

JPEG (17.19 MB)

References & Resources

  • Alaska Public Media (2025, August 12)
    This is the hidden content, please
    . Accessed May 7, 2026.
  • AP News (2026, April 12)
    This is the hidden content, please
    . Accessed May 7, 2026.
  • NASA Earth Observatory (2024, November 12)
    This is the hidden content, please
    . Accessed May 7, 2026.
  • Shugar, D. H., et al. (2026)
    This is the hidden content, please
    . Science, 392 (6798).
  • University of Alaska Fairbanks (2025, August 12)
    This is the hidden content, please
    . Accessed May 7, 2026.
  • U.S. Geological Survey (2025, August 13)
    This is the hidden content, please
    . Accessed May 7, 2026.

You may also be interested in:

Stay up-to-date with the latest content from NASA as we explore the universe and discover more about our home planet.

This is the hidden content, please

This is the hidden content, please

This is the hidden content, please

This is the hidden content, please

4 min read

Satellite-based radar images show where a powerful earthquake in the Yukon, Canada, sent rock, snow, and ice spilling across the…

Article
This is the hidden content, please

This is the hidden content, please

This is the hidden content, please

This is the hidden content, please

3 min read

Heavy rains from Tropical Cyclone Maila triggered a deadly landslide in the mountains of East New Britain.

Article
This is the hidden content, please

This is the hidden content, please

This is the hidden content, please

This is the hidden content, please

5 min read

Scientists relied on satellite data to understand how the Antarctic glacier lost so much ice so rapidly.

Article

This is the hidden content, please

0

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
 Share
Go to topic listing

  • Vote for the server

    To vote for this server you must login.

    Jim Carrey Flirting GIF

  • Recently Browsing   0 members

    • No registered users viewing this page.

Important Information

Privacy Notice: We utilize cookies to optimize your browsing experience and analyze website traffic. By consenting, you acknowledge and agree to our Cookie Policy, ensuring your privacy preferences are respected.

  I accept