EVOLUTION OF VARIEGATED GLACIER, ALASKA, U.S.A., PRIOR TO ITS SURGE
ABSTRACT. During the decade prior to its 1982-83 surge, Variegated Glacier experienced progressive changes in geometry and velocity. It thickened in the upper 60 % and thinned in the lower 40 % of its 20 km length. Thickness changes were up to 20%. Annual velocity increased by up to 500%, reaching a...
Main Author: | |
---|---|
Other Authors: | |
Format: | Text |
Language: | English |
Subjects: | |
Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.634.3463 http://www.igsoc.org/journal/34/117/igs_journal_vol34_issue117_pg154-169.pdf |
id |
ftciteseerx:oai:CiteSeerX.psu:10.1.1.634.3463 |
---|---|
record_format |
openpolar |
spelling |
ftciteseerx:oai:CiteSeerX.psu:10.1.1.634.3463 2023-05-15T16:20:30+02:00 EVOLUTION OF VARIEGATED GLACIER, ALASKA, U.S.A., PRIOR TO ITS SURGE C. F. Raymond The Pennsylvania State University CiteSeerX Archives application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.634.3463 http://www.igsoc.org/journal/34/117/igs_journal_vol34_issue117_pg154-169.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.634.3463 http://www.igsoc.org/journal/34/117/igs_journal_vol34_issue117_pg154-169.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://www.igsoc.org/journal/34/117/igs_journal_vol34_issue117_pg154-169.pdf text ftciteseerx 2016-01-08T15:37:28Z ABSTRACT. During the decade prior to its 1982-83 surge, Variegated Glacier experienced progressive changes in geometry and velocity. It thickened in the upper 60 % and thinned in the lower 40 % of its 20 km length. Thickness changes were up to 20%. Annual velocity increased by up to 500%, reaching a maximum of 0.7 m d- 1 in the year before surge onset. Amplitude of seasonal variation in velocity increased up to 0.3 m d- 1 by 1978, but did not increase markedly after that. The changes in velocity were larger than predicted from changes in deformation rate caused by changes in shear stress and depth. This anomalous velocity was especially large after 1978 in the zone of thickening on the upper glacier. If it is assumed to arise from basal sliding, the inferred pattern of sliding shows qualitative features consistent with a direct effect from basal shear stress and an inverse effect from effective normal stress. A drop in effective normal stress in a zone of decreasing surface slope up-glacier from the largest thickness increase may have been significant in the initiation of surge motion in 1982. 1. Text glacier Alaska Unknown |
institution |
Open Polar |
collection |
Unknown |
op_collection_id |
ftciteseerx |
language |
English |
description |
ABSTRACT. During the decade prior to its 1982-83 surge, Variegated Glacier experienced progressive changes in geometry and velocity. It thickened in the upper 60 % and thinned in the lower 40 % of its 20 km length. Thickness changes were up to 20%. Annual velocity increased by up to 500%, reaching a maximum of 0.7 m d- 1 in the year before surge onset. Amplitude of seasonal variation in velocity increased up to 0.3 m d- 1 by 1978, but did not increase markedly after that. The changes in velocity were larger than predicted from changes in deformation rate caused by changes in shear stress and depth. This anomalous velocity was especially large after 1978 in the zone of thickening on the upper glacier. If it is assumed to arise from basal sliding, the inferred pattern of sliding shows qualitative features consistent with a direct effect from basal shear stress and an inverse effect from effective normal stress. A drop in effective normal stress in a zone of decreasing surface slope up-glacier from the largest thickness increase may have been significant in the initiation of surge motion in 1982. 1. |
author2 |
The Pennsylvania State University CiteSeerX Archives |
format |
Text |
author |
C. F. Raymond |
spellingShingle |
C. F. Raymond EVOLUTION OF VARIEGATED GLACIER, ALASKA, U.S.A., PRIOR TO ITS SURGE |
author_facet |
C. F. Raymond |
author_sort |
C. F. Raymond |
title |
EVOLUTION OF VARIEGATED GLACIER, ALASKA, U.S.A., PRIOR TO ITS SURGE |
title_short |
EVOLUTION OF VARIEGATED GLACIER, ALASKA, U.S.A., PRIOR TO ITS SURGE |
title_full |
EVOLUTION OF VARIEGATED GLACIER, ALASKA, U.S.A., PRIOR TO ITS SURGE |
title_fullStr |
EVOLUTION OF VARIEGATED GLACIER, ALASKA, U.S.A., PRIOR TO ITS SURGE |
title_full_unstemmed |
EVOLUTION OF VARIEGATED GLACIER, ALASKA, U.S.A., PRIOR TO ITS SURGE |
title_sort |
evolution of variegated glacier, alaska, u.s.a., prior to its surge |
url |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.634.3463 http://www.igsoc.org/journal/34/117/igs_journal_vol34_issue117_pg154-169.pdf |
genre |
glacier Alaska |
genre_facet |
glacier Alaska |
op_source |
http://www.igsoc.org/journal/34/117/igs_journal_vol34_issue117_pg154-169.pdf |
op_relation |
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.634.3463 http://www.igsoc.org/journal/34/117/igs_journal_vol34_issue117_pg154-169.pdf |
op_rights |
Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
_version_ |
1766008422431457280 |