| Summary: | Hubbard Glacier, located in Yakutat Bay Alaska is the largest tidewater glacier in North America. Unlike any other glaciers in Alaska, Hubbard Glacier is in an advancement phase. Looking at imagery dating back as far as 1978 shows that Hubbard Glacier has been continually advancing, with no signs of stopping. There have been two instances in recent history where Hubbard Glacier has advanced far enough to close off Russell Fjord, turning it into a lake which is constantly fed with stream runoff from the surrounding mountains. Both instances ended in the terminus of Hubbard Glacier giving way, creating a glacial outburst flood. However, a closure could also lead to Russell Lake overflowing into the Situk River, creating possible flooding of the Yakutat people’s infrastructure. In order to study this phenomenon, glacier velocity, terminus advance, and calving rate data was collected from Landsat imagery for the 2002 closure and was compared with recent years. Using the Landsat imagery in conjunction with CIAS image correlation software, velocities were obtained for the terminus of the glacier every other year from 2002 to 2014. These velocities were averaged for the entire glacier as well as for different areas of the terminus. From the data collected, Hubbard Glacier generally shows surges of velocity in the spring, with the largest surge having a velocity of 12.63 meters a day in 2010. Terminus advance was detected by digitizing the terminus each year and calculating how far it had moved. The general increase in velocity from year to year seems to be analogous with the advance of the terminus. While a prolonged surge in 2002 was able to close off Russell Fjord, three bigger surges with shorter durations in the years 2008, 2010, and 2012 were not able to quite close off the fjord. However, the trend of terminus advance seems to be increasing, meaning another closure is forecasted to happen in the near future. This research was done with help and resources provided by the Polar Geospatial Center (PGC).
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