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Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier: 1. Observations

Meier, Mark and Lundstrom, Scott and Stone, Dan and Kamb, Barclay and Engelhardt, Hermann and Humphrey, Neil and Dunlap, William W. and Fahnestock, Mark and Krimmel, Robert M. and Walters, Roy (1994) Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier: 1. Observations. Journal of Geophysical Research B, 99 (B8). pp. 15219-15229. ISSN 0148-0227. https://resolver.caltech.edu/CaltechAUTHORS:20140523-100401162

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Abstract

Measurements of glacier flow velocity and basal water pressure at two sites on Columbia Glacier, Alaska, are combined with meteorological and hydrologic data to provide an observational basis for assessing the role of water storage and basal water pressure in the rapid movement of this large glacier. During the period from July 5 to August 31, 1987, coordinated observations were made of glacier surface motion and of water level in five boreholes drilled to (or in one case near to) the glacier bed at two sites, 5 and 12 km from the terminus. Glacier velocities increased downglacier in this reach from about 4 m d^−1 to about 7 m d^−1. Three types of time variation in velocity and other variables were revealed: (1) Diurnal fluctuation in water input/output, borehole water level, and ice velocity (fluctuation amplitude 5 to 8%); (2) Speed-up events in glacier motion (15–30% speed up), lasting about 3 days, and occurring at times of enhanced input of water, in some cases from rain and in others from ice ablation enhanced by strong, warm winds; (3) “Extra-slowdown” events, in which, after a speed-up event, the ice velocity decreased in about 3 days to a level consistently lower than that prior to the speed-up event. All of the time variations in velocity were due, directly or indirectly, to variations in water input to the glacier. The role of basal water in causing the observed glacier motions is interpreted by Kamb et al. (this issue).


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/94JB00237DOIArticle
ORCID:
AuthorORCID
Walters, Roy0000-0002-1835-6078
Additional Information:© 1994 American Geophysical Union. Manuscript Accepted: 13 January 1994; Manuscript Received: 16 June 1993. Financial support for this work was provided by NSF grants DPP-8619348 to the University of Colorado and DPP-8619352 to the California Institute of Technology. The automated EDM system was developed by Bruce Vaughn. Help in the field work was provided by Carolyn Driedger, Mark Wumpkes, and Matthias Blume. To our helicopter pilot, Roger Kramer, we owe a special debt of gratitude.
Funders:
Funding AgencyGrant Number
NSFDPP-8619348
NSFDPP-8619352
Issue or Number:B8
Record Number:CaltechAUTHORS:20140523-100401162
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140523-100401162
Official Citation:Meier, M., S. Lundstrom, D. Stone, B. Kamb, H. Engelhardt, N. Humphrey, W. W. Dunlap, M. Fahnestock, R. M. Krimmel, and R. Walters (1994), Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier: 1. Observations, J. Geophys. Res., 99(B8), 15219–15229, doi:10.1029/94JB00237.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45904
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:27 May 2014 20:08
Last Modified:18 Nov 2020 20:18

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