The Uplift of Unteraargletscher at the Beginning of the Melt Season—a Consequence of Water Storage at the Bed?

Abstract The results of systematic movement studies carried out by means of an automatic camera on the Unteraargletscher since 1969 (Flotron, 1973) are discussed together with more recent findings from theodolite measurements made at shorter intervals and over a longer section of the glacier. In add...

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Published in:Journal of Glaciology
Main Authors: Iken, A., Flotron, A., Haeberli, W., Röthlisberger, H.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 1979
Subjects:
Online Access:http://dx.doi.org/10.1017/s0022143000030203
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000030203
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spelling crcambridgeupr:10.1017/s0022143000030203 2024-04-07T07:53:41+00:00 The Uplift of Unteraargletscher at the Beginning of the Melt Season—a Consequence of Water Storage at the Bed? Iken, A. Flotron, A. Haeberli, W. Röthlisberger, H. 1979 http://dx.doi.org/10.1017/s0022143000030203 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000030203 en eng Cambridge University Press (CUP) Journal of Glaciology volume 23, issue 89, page 430-432 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1979 crcambridgeupr https://doi.org/10.1017/s0022143000030203 2024-03-08T00:35:31Z Abstract The results of systematic movement studies carried out by means of an automatic camera on the Unteraargletscher since 1969 (Flotron, 1973) are discussed together with more recent findings from theodolite measurements made at shorter intervals and over a longer section of the glacier. In addition to the typical spring/early-summer maximum of velocity known from other glaciers, an upward movement of up to 0.6 m has been recorded at the beginning of the melt season. It was followed, after various fluctuations of the vertical velocity, by a similar but slower downward movement which continued at an almost constant rate for about three months. The uplift was not confined to the section covered by the camera but occurred nearly simultaneously in profiles located 1 km below and 2 km above. The times of maximum upward velocity (increases of up to 140 mm/d) coincided approximately with periods of large horizontal velocity and occurred after increases of melt-rate. The following explanations for the variations of vertical velocity are considered: (1) Changes of longitudinal strain-rate. (2) Changes of the sliding velocity in a channel of variable width and with a bed slope deviating from horizontal. (3) Changes of volume due to opening or closing of crevasses. (4) Swelling or contraction of veins at the grain edges. (5) Growth (and closure) of cavities in the interior of the glacier. (6) Changes of large-scale water storage at the bed. Although all of the mechanisms (1)–(5) have some effect on the vertical ice movement, they cannot account for the observed variations of vertical velocity. We therefore conclude that large-scale water storage at the bed is the main cause of the uplift. Apparently the storage system is efficiently connected with the main subglacial drainage channels only during times of very high water pressure in the channels. The findings are of some interest to the concepts of glacier sliding: As mentioned above the maxima of horizontal velocity—and thus of the sliding velocity—have not been ... Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 23 89 430 432
institution Open Polar
collection Cambridge University Press
op_collection_id crcambridgeupr
language English
topic Earth-Surface Processes
spellingShingle Earth-Surface Processes
Iken, A.
Flotron, A.
Haeberli, W.
Röthlisberger, H.
The Uplift of Unteraargletscher at the Beginning of the Melt Season—a Consequence of Water Storage at the Bed?
topic_facet Earth-Surface Processes
description Abstract The results of systematic movement studies carried out by means of an automatic camera on the Unteraargletscher since 1969 (Flotron, 1973) are discussed together with more recent findings from theodolite measurements made at shorter intervals and over a longer section of the glacier. In addition to the typical spring/early-summer maximum of velocity known from other glaciers, an upward movement of up to 0.6 m has been recorded at the beginning of the melt season. It was followed, after various fluctuations of the vertical velocity, by a similar but slower downward movement which continued at an almost constant rate for about three months. The uplift was not confined to the section covered by the camera but occurred nearly simultaneously in profiles located 1 km below and 2 km above. The times of maximum upward velocity (increases of up to 140 mm/d) coincided approximately with periods of large horizontal velocity and occurred after increases of melt-rate. The following explanations for the variations of vertical velocity are considered: (1) Changes of longitudinal strain-rate. (2) Changes of the sliding velocity in a channel of variable width and with a bed slope deviating from horizontal. (3) Changes of volume due to opening or closing of crevasses. (4) Swelling or contraction of veins at the grain edges. (5) Growth (and closure) of cavities in the interior of the glacier. (6) Changes of large-scale water storage at the bed. Although all of the mechanisms (1)–(5) have some effect on the vertical ice movement, they cannot account for the observed variations of vertical velocity. We therefore conclude that large-scale water storage at the bed is the main cause of the uplift. Apparently the storage system is efficiently connected with the main subglacial drainage channels only during times of very high water pressure in the channels. The findings are of some interest to the concepts of glacier sliding: As mentioned above the maxima of horizontal velocity—and thus of the sliding velocity—have not been ...
format Article in Journal/Newspaper
author Iken, A.
Flotron, A.
Haeberli, W.
Röthlisberger, H.
author_facet Iken, A.
Flotron, A.
Haeberli, W.
Röthlisberger, H.
author_sort Iken, A.
title The Uplift of Unteraargletscher at the Beginning of the Melt Season—a Consequence of Water Storage at the Bed?
title_short The Uplift of Unteraargletscher at the Beginning of the Melt Season—a Consequence of Water Storage at the Bed?
title_full The Uplift of Unteraargletscher at the Beginning of the Melt Season—a Consequence of Water Storage at the Bed?
title_fullStr The Uplift of Unteraargletscher at the Beginning of the Melt Season—a Consequence of Water Storage at the Bed?
title_full_unstemmed The Uplift of Unteraargletscher at the Beginning of the Melt Season—a Consequence of Water Storage at the Bed?
title_sort uplift of unteraargletscher at the beginning of the melt season—a consequence of water storage at the bed?
publisher Cambridge University Press (CUP)
publishDate 1979
url http://dx.doi.org/10.1017/s0022143000030203
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000030203
genre Journal of Glaciology
genre_facet Journal of Glaciology
op_source Journal of Glaciology
volume 23, issue 89, page 430-432
ISSN 0022-1430 1727-5652
op_doi https://doi.org/10.1017/s0022143000030203
container_title Journal of Glaciology
container_volume 23
container_issue 89
container_start_page 430
op_container_end_page 432
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