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

• Published in: Annals of Glaciology
• Main Authors: Campbell, Seth, Roy, Samuel, Kreutz, Karl, Arcone, Steven A, Osterberg, Erich C, Koons, Peter
• Format: Text
• Language: unknown
• Published: Dartmouth Digital Commons 2013
• Subjects: Earth Sciences; Glaciology; Physical Sciences and Mathematics; Mount Hunter; glacier; Alaska
• Online Access: https://digitalcommons.dartmouth.edu/facoa/461; https://doi.org/10.3189/2013AoG63A266

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) ???????? 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.