Alaska Earthquake Center Although no one was in Tracy Arm (thankfully!) when the landslide crashed into the water on Sunday, we are now starting to get some images of just how large that event was. These before-and-after satellite images show places where the tsunami scoured the fjord walls down to bedrock. (The locations of the different insets can be found in the main image by the differently colored boxes.) The first image uses the visible spectrum, like a normal photograph. The second image shows Near Infrared, which highlights vegetation, so that the newly-bare rock is more evident. Note the run-up of the tsunami indicated by new bare rock on the opposing fjord wall. That speck on Sawyer Island in the after images is a lone tree that survived the tsunami! Thank you to Planet for the data and Simon Plank, DLR for sharing these images.
The image is a composite of satellite images showing a landslide in Southeast Alaska Fjord, dated August 10, 2025, monitored by PlanetScope. The central feature is a fjord winding through rugged, mountainous terrain with visible sections of snow and ice. Alongside the primary image, smaller insets capture the fjord at different timestamps before and after the landslide. Dark green forests cover the mountains with patches of white indicating snow. The water in the fjord appears teal in color. In the bottom section, there are six smaller images showing closer views, illustrating the tsunami run-up at multiple locations, the landslide scar, and debris spread in the fjord. The right inset shows the South Sawyer Glacier and other landscape alterations. A map key on the top right indicates orientation and scale.
The image shows satellite imagery of a landslide in the Southeast Alaska Fjord, captured on August 10, 2025, by PlanetScope. The main portion of the image highlights a deep fjord with distinct red and blue tones. The red areas represent vegetation or land, while the blue parts indicate water bodies. Snow-covered peaks and mountain ranges provide stark white contrasts against the red landscape. The fjord follows a winding course through the mountainous region. Several smaller images below the main image show more detailed views of specific areas within the fjord, with some annotated for specific features like "Tsunami run-up" and "Landslide scarp." A scale and arrow for north orientation are present in the upper right corner. Text in the image provides information about the event and links for further details.
More info on the Tracy Arm landslide/tsunami from the Alaska Earthquake Center
AEC Facebook post
www.facebook.com/share/p/19GF...
AEC page
earthquake.alaska.edu
🧪⚒️🌊
#alaska
#landslide
#TracyArm
#tsunami
#alaskaearthquakecenter
#AEC
