Crevasse Detection and Avoidance for Safe Traversing on the Dynamic and Annually Changing Margin of the Greenland Ice Sheet
Abstract
The Greenland Inland Traverse (GrIT) is an ~740 mile overland resupply effort to transport fuel and cargo from a deep-water port (Thule) to inland research stations (NEEM and Summit). The current route starts at the margin of the Greenland Ice Sheet where the original Thule Take-Off (Camp TUTO) served as a staging area for the traverse to Camp Century during the 1960’s. Crew safety is of utmost importance, and while a short and efficient route is desirable, this area has historically been known to be crevassed and the first ~70 miles have proven to be increasingly dynamic since GrIT’s initial route assessment in 2007. Through a combination of high-resolution satellite imagery analysis, ground penetrating radar (GPR) analysis, route planning and guidance, precise vehicle maneuvering, and mountaineering safety measures, the GrIT’s Strategic Crevasse Avoidance Team (SCAT) has successfully navigated around and documented newly formed crevasses each operational season. Here, we present our methodology for successful navigation, and show the imagery analysis and field assessment by which we’ve discovered increasing numbers and sizes of crevasses and crevasse fields in the ice margin. Half-meter resolution WorldView 1 satellite imagery is taken each August/September to expose crevasses after summer melting has occurred and bridges are sagging or have failed. While it is not possible to determine crevasse widths or bridge depths with this imagery, it does allow identification of most crevasse locations, their lengths and overall crevasse-field size. This provides a roadmap for SCAT to navigate in-and-around crevasse fields. Field measurements show crevasses ranging in size from several centimeters to large chasms tens of meters across. Bridge depths measured in March 2010 ranged from 1.5 meters up to 9 meters. While the data confirm this area is dynamic and rapidly changing, it is difficult to determine whether increased glacial speeds (i.e. surge), a degree of isostatic rebound, severe surface vertical degradation or another type of natural event (i.e. earthquake) is causing the increased number of crevasses in this area. Early results of satellite radar interferometry will also be presented to assess the nature of ice movement within this area over time. If the rapid formation of these new large crevasse fields, in the last three years, is an indicator of crevasse formation rates in this area, then GrIT navigation onto the Greenland Ice Sheet could be impaired in coming years and active crevasse mitigation measures (i.e. blasting or bridging) will have to be considered.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.C23B0624M
- Keywords:
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- 0700 CRYOSPHERE;
- 0720 CRYOSPHERE / Glaciers;
- 0726 CRYOSPHERE / Ice sheets