Remote Sensing Models and Methods for Image Processing 

 In early June 1986, the advancing face of Hubbard Glacier, located in Southeastern Alaska, closed off the entrance to Russell Fiord with an ice dam that created the world's largest known modern glacier-dammed lake. This Landsat TM CIR composite is from September 11, 1986. Over 70 miles long, the Hubbard is North America's largest tidewater glacier. The Valerie Glacier, a tributary to the Hubbard, moved at rates of up to 130 feet per day causing the Hubbard to advance more than a mile during the summer of 1986. The current advance is part of a long-term cycle of advance and retreat. About 800 years ago, the glacier extended all the way to the mouth of Yakutat Bay. Because of the ice dam, Russell Fiord became a lake and water level rose at a very rapid rate during the summer months. Marine mammals (porpoise and seals) and other marine life were trapped. If the lake had continued to rise, it was predicted that it would overflow to the south within a year. The dam formed by the surging glacier broke on October 8, 1986, restoring the dammed-up lake to a fiord, and recovering the vital sea-water environment for the marine life. It is expected that the glacier will continue to surge and form another dam in the future as the cycle continues. (Image data and description courtesy U.S. Geological Survey [Meridian Data, 1991 #528]).