HR: 14:20h
AN: C12B-03    [PDF]
TI: Englacial Crevasses: Observations and Theory.
AU: * Humphrey, N F
EM: neil@uwyo.edu
AF: Univ. of Wyoming, Dept. of Geology and Geophysics, Laramie, WY 82071 United States
AU: Harper, J T
EM: joelh@uwyo.edu
AF: Univ. of Wyoming, Dept. of Geology and Geophysics, Laramie, WY 82071 United States
AU: McGee, B
EM: cyvira@uwyo.edu
AF: Univ. of Wyoming, Dept. of Geology and Geophysics, Laramie, WY 82071 United States
AU: Pfeffer, W T
EM: pfeffer@tintin.colorado.edu
AF: Univ. of Colorado, Institute of Arctic and Alpine Research, Boulder, CO 80309 United States
AB: Recent observations on the Bench Glacier and other temperate glaciers in the coastal mountains of Southeast Alaska have shown the existence and importance of crevasses that crack over the full glacier depth. Direct video and hydrologic observations show these pervasive crevasses to be rapidly evolving and laterally and vertically extensive. Hydrologic monitoring demonstrates that the crevasses are connected to the surface, basal, and englacial hydraulic systems, and form part of the seasonal development of the englacial water system. We present data, including englacial video, of evolving crevasses at depths from 100 to 200m. The data demonstrate the existence and extent of crevassing well below the region of surface crevassing and into the region of fully compressive stresses (non-deviatoric). Preliminary theoretical work is presented discussing the role of water weight driven crevasse propagation. The theory addresses the propagation speeds of crevasses. It is concluded that crevasse propagation may be controlled by the available volume flux of water in the hydraulic system, not by classic crack propagation considerations. Some of the effects of modeling crevassing in 3 dimensions, as opposed to 2 dimensions, is discussed, where it is concluded that 3 dimensional crevassing should allow crevasses which greatly facilitate the creation of a connected and through draining glacial hydraulic system.
DE: 1827 Glaciology (1863)
DE: 1863 Snow and ice (1827)
DE: 1899 General or miscellaneous
DE: 5104 Fracture and flow
SC: Cryosphere [C]
MN: 2003 Fall Meeting