Strain-rate estimates for crevasse formation at an alpine ice divide: Mount Hunter, Alaska

• Main Authors: Seth Campbell, Samuel Roy, Karl Kreutz, Steven A Arcone, Erich C Osterberg, Peter Koons
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Mount Hunter; glacier; Alaska
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1040.9571; http://www.dartmouth.edu/%7Eeosterberg/images/Campbell%20et%20al.,%202013%20Strain%20rate%20estimates%20from%20Hunter.pdf

ABSTRACT. Crevasse initiation is linked to strain rates that range over three orders of magnitude (0.001 and 0.163 a -1 ) as a result of the temperature-dependent nonlinear rheological properties of ice and from water and debris inclusions. Here we discuss a small cold glacier that contains buried crevasses at and near an ice divide. Surface-conformable stratigraphy, the glacier's small size, and cold temperatures argue for limited rheological variability at this site. Surface ice-flow velocities of (1.2-15.5) AE AE 0.472 m a -1 imply classic saddle flow surrounding the ice divide. Numerical models that incorporate field-observed boundary conditions suggest extensional strain rates of 0.003-0.015 a -1 , which fall within the published estimates required for crevasse initiation. The occurrence of one crevasse beginning at 50 m depth that appears to penetrate close to the bed suggests that it formed at depth. Field data and numerical models indicate that a higher interior stress at this crevasse location may be associated with steep convex bed topography; however, the dynamics that caused its formation are not entirely clear.