The 2000/01 Surge of Yanert Glacier, Alaska

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ABSTRACT TrufferOPP-0126363There are a number of surge-type glaciers in the central Alaska Range and most of them overlying the Denali Fault . The actual occurrence of a surge, however, is rare because of the long recurrence time which is about 50-100 years and only three glaciers have been recorded to surge repeatedly in this region. One of these is the Yanert which is known to have last surged in 1942. This is very different from the glaciers in southeast Alaska where surges are often repeated in less than twenty years. The exact causes and the behavior of surges are not known, therefore, it is important to take advantage of opportunities for more data collection whenever it arises. Unfortunately, the exact year or time of a surge is very difficult to predict and it is impossible to plan for adequate field work in advance. The Yanert Glacier is located in the central Alaska Range, but little is known about it other than it is a surge-type glacier and a surge had been observed in 1942. The recent surge started in the late winter of 1999/2000, but most of it went unnoticed. In April 2001, it had restarted again and developed into a major surge . Because no surges have been observed to last more than two years, the Yanert surge is likely to stop this summer and not resume next winter. The Principal Investigators will fly to the terminus of Yanert Glacier and install two time lapse cameras. One will observe the surge front that is currently about five kilometers from the glacier terminus. It will be used to measure the rate of advance of the surge front and to establish the time when the advance stops. A second camera will be placed in front of the glacier. The end of the surge is expected to coincide with a big flood. This camera will record if and when the flood occurs. The Principal Investigators will also record the position of the surge front, using hand held GPS units. At the end of the season, they will fly a profile of the glacier with an airborne altimetry system and retrieve the time lapse cameras. The profile will be used to estimate the total mass transport of ice that occurred as a result of the surge.