An unexpected color palette reveals the character of Southeast Alaska's iconic glacial landscape. To the human eye, glacier ice usually appears white with a bluish tinge. But in this false-color satellite image, the rippled ice of Alaska's Malaspina Glacier looks more like it's hot (though it's not).
Satellite imaging reveals unique hues
This view of the Malaspina Glacier on the southeastern coast of Alaska was taken by Landsat9's OLI-2 (Operational Land Imager-2) on October 27, 2023. Shown here are the coastal/aerosol, near-infrared and shortwave infrared bands: a combination of bands 1-5-7. In this configuration, water-like features appear in red, orange, and yellow; vegetation appears in green; and rocks appear in shades of blue.
Malaspina Glacier: a geological wonder
The vast Malaspina Glacier (or Sít’Tlein, Tlingit for “Great Glacier”) lies mostly within the Wrangell-St. Lawrence territory. Elias National Park. With an area of approximately 1,680 square miles (4,350 square kilometers), it is the largest foothill glacier in the world and is larger than the state of Rhode Island. Its main source of ice is the Seward Glacier, which spills from the St. Elias Mountains onto the vast coastal plain. Several other glaciers, such as Agassiz Glacier, also fan out into the plain and merge to form the larger Malaspina Glacier.
Moraine: a sign of glacial movement
The dark blue-purple lines on the ice are moraines, areas where soil, rock and other debris have been scraped up by the glacier and deposited along its edges. The jagged pattern of debris is caused by changes in the speed of the ice. Glaciers in this part of Alaska periodically "swell," or tilt forward, for one to several years. Because of this irregular flow, the moraines can fold, compress, and shear, creating the characteristic texture seen on Malaspina.
Interaction of glaciers and oceans
At the terminus, or terminus, of the glacier, a slender strip of land forms a barrier between the ice and the Gulf of Alaska. A comparison of satellite images over time shows that a lagoon system has developed along the barrier over the past few decades. Small patches of rust-red open water can be seen here. According to recent research, some of this water is almost as salty as the ocean, meaning relatively warm water is in contact with ice. This could lead to massive calving and accelerate glacier retreat.