Monitoring an Active Rift System at the Front of Amery Ice Shelf, East Antarctica

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This award supports a comprehensive study of rift growth on the Amery Ice Shelf (AIS), East Antarctica, using a combination of in situ and remote sensing data with numerical modeling. On the AIS there is an opportunity to examine an active rift system, which is a combination of two longitudinal-to-flow rifts, which originated at the ice shelf front in the suture zones between merging flowbands, and two transverse-to-flow rifts, which formed at the tip of the western longitudinal rift around 1996. Work in progress indicates that these two transverse rifts do not propagate independently of each other, but somehow grow more or less synchronously. The longest of these rifts-the eastern one-grows at an average rate of about 8m per day. When it meets the eastern longitudinal rift, an event that is expected to occur during the funding period (mid-2006), an iceberg (~30 x 30 km) will calve. Based on observations collected over the past half century, there is reason to believe that such a calving event may be a part of a repetitive sequence. In the proposed project, the expansion and propagation of both transverse rifts will be studied using a network of GPS and seismometers deployed around the tip of each transverse rift. Once the iceberg has calved, the effects its calving has on the dynamics of the ice shelf and the activation of previously inactive rifts will also be studied. Insofar as the rate of calving activity is a proxy for local and regional climate conditions, a broader impact of the proposed work is directly related to the socio-environmental topics of climate and sea-level change. The subject of iceberg calving has a history of sparking a great deal of interest from the media and the public alike, especially since the recent large calving events from the Ross and Ronne ice shelves and the remarkably sudden break-up of the Larsen Ice Shelf. The work will involve at least one graduate student, and will involve a partnership with a local charter high school. Field work, instrument deployments, and data collection and analysis will be conducted in close collaboration with the Australian Antarctic Division and the University of Tasmania, which has been a crucial component of research conducted to date. This project will also make use of the Scripps Institution of Oceanography Visualization Center as a means to display results to faculty and researchers of the University of California, San Diego, undergraduate and graduate students, to school children and their teachers, and ultimately to the visiting public.