Glacial Lake Outbreak

August 22, 2002


Provided by: USGS - Water Resources of Alaska
Summary authors & editors: Martin Ruzek; USGS

These photographs show an eastward-looking view of a small section of the Hubbard Glacier in southeastern Alaska. Hubbard Glacier is the largest tidewater glacier on the North American continent. It has been thickening and advancing toward the Gulf of Alaska since it was first mapped 1895 in stark contrast with most glaciers, which have thinned and retreated during the last century. The advancing terminus of the glacier created a "squeeze-push" moraine in front of Gilbert Point that blocked the tidal exchange between Disenchantment Bay (bottom of photos) and Russell Fiord (top of photos), creating Russell Lake earlier this summer. The lake rose to 18.6 m (61 ft) above sea level over 2 1/2 months before the rock and ice dam broke, creating the second largest glacial lake outburst worldwide in historical times. On August 14 the trapped water in the 70-sq mi (18,000 ha) lake broke free to the ocean in a spectacular roiling and chaotic 36 hours, making the torrential channel into the sea an extremely fast-moving and dangerous river full of large chunks of ice and debris.

Photographs made by the U.S. Geological Survey, the U.S. Forest Service, Yakutat Range District and National Park Service, Yakutat Ranger Station.

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