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Three-dimensional deformation measured in an alaskan glacier
1J. T. Harper and N. F. Humphrey, Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071, USA. W. T. Pfeffer, Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA.
Science (New York, N.Y.)
|August 28, 1998
Summary
Glacier flow is complex, with most motion occurring at the bed. Ice deformation rates varied with depth but were independent of sliding speed, challenging simple models.
Area of Science:
- Glaciology
- Geophysics
- Earth Science
Background:
- Temperate valley glaciers exhibit complex flow dynamics.
- Understanding glacier motion is crucial for predicting sea-level rise and water resources.
Purpose of the Study:
- To investigate the three-dimensional ice flow field of Worthington Glacier.
- To determine the contributions of basal sliding and internal ice deformation to glacier motion.
- To assess the validity of common modeling assumptions like plane strain.
Main Methods:
- Measurements of ice movement using 28 boreholes.
- Analysis of surface motion and strain rates within the ice.
- Characterization of the three-dimensional flow field.
Main Results:
- Basal sliding accounted for 60-70% of the glacier's surface motion.
- Ice strain rates were low in the upper 120 meters, increasing rapidly towards the bed.
- Internal ice deformation showed no correlation with temporal changes in basal sliding rate.
Conclusions:
- Worthington Glacier exhibits significant basal sliding.
- Plane strain is an inadequate assumption for modeling the viscous flow of this glacier.
- Detailed 3D measurements are essential for accurate glacier flow modeling.