USGS/Cascades Volcano Observatory, Vancouver, Washington
REPORT:
Ice Volumes on Cascade Volcanoes; Mount Rainier, Mount Hood, Three Sisters, and Mount Shasta
--
Driedger, C.L., and Kennard, P.M., 1986,
Ice Volumes on Cascade Volcanoes; Mount Rainier, Mount Hood, Three Sisters, and Mount Shasta:
U.S. Geological Survey Professional Paper 1365, 28p.
Abstract
During the eruptions of Mount St. Helens the occurrence of floods
and mudflows made apparent the need for predictive water-hazard
analysis of other Cascade volcanoes. A basic requirement for such
analysis is information about the volumes and distributions of snow
and ice on other volcanoes.
A radar unit contained in a backpack was used to make point
measurements of ice thickness on major glaciers of Mount Rainier,
Wash.; Mount Hood, Oreg.; the Three Sisters, Oreg.; and Mount
Shasta, Calif. The measurements were corrected for slope and were
used to develop subglacial contour maps from which glacier volumes
were measured.
These values were used to develop estimation methods for finding
volumes of unmeasured glaciers. These methods require a knowledge
of glacier slope, altitude, and area and require an estimation of basal
shear stress, each estimate derived by using topographic maps up-
dated by aerial photographs. The estimation methods were found to
be accurate within +/-20 percent on measured glaciers and to be
within +/-25 percent when applied to unmeasured glaciers on the
Cascade volcanoes. The estimation methods may be applicable to
other temperate glaciers in similar climatic settings.
Areas and volumes of snow and ice are as follows: Mount Rainier,
991 million ft2, 156 billion ft3; Mount Hood, 145 million ft2, 12 billion
ft3; Three Sisters, 89 million ft2, 6 billion ft3; and Mount Shasta, 74
million ft2, 5 billion ft3.
The distribution of ice and fim patches within 58 glacierized basins
on volcanoes is mapped and listed by altitude and by watershed to
facilitate water-hazard analysis.
the preparation of subglacial contour and isopach maps
included in this paper, along with the resulting volume
calculations. The descriptions of ice-radar operation
and methods for data reduction, calculation of glacier
volume, and error totals in calculating glacier volume
are condensed from a study by Kennard (1983).
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02/24/06, Lyn Topinka