Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland
During a motion event on Unteraargletscher, Bernese Alps, Switzerland, in spring 1996, surface velocities were measured up to eight times a day at four different locations along the central flowline using global positioning system equipment. In addition, accumulated vertical strains over the uppermo...
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ftnerc:oai:nora.nerc.ac.uk:13394 2023-05-15T16:57:37+02:00 Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland Gudmundsson, G. Hilmar 2002 http://nora.nerc.ac.uk/id/eprint/13394/ http://www.ingentaconnect.com/content/igsoc/jog/2002/00000048/00000163/art00010 unknown International Glaciological Society Gudmundsson, G. Hilmar orcid:0000-0003-4236-5369 . 2002 Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland. Journal of Glaciology, 48 (163). 566-574. https://doi.org/10.3189/172756502781831043 <https://doi.org/10.3189/172756502781831043> Glaciology Publication - Article PeerReviewed 2002 ftnerc https://doi.org/10.3189/172756502781831043 2023-02-04T19:28:34Z During a motion event on Unteraargletscher, Bernese Alps, Switzerland, in spring 1996, surface velocities were measured up to eight times a day at four different locations along the central flowline using global positioning system equipment. In addition, accumulated vertical strains over the uppermost 50 and 100 m were measured at a location where the total ice thickness is 260 m. The motion event was accompanied by high horizontal and vertical strain rates as compared to annual mean values. A reversal in strain regime was observed, with horizontal strain rates changing to extension while vertical strain rates became compressive. This strain-rate reversal coincided, within the temporal resolution of the data, with a maximum in vertical ice displacement at the surface. Within a day, variations in vertical strain from 0.04 a(-1) to -0.06 a(-1) were observed over the uppermost 100 m. Vertical stretching is estimated to have contributed to at least 20% of the anomalous vertical ice movement at the surface. There were significant differences between measured longitudinal strain, averaged over a distance corresponding to a few ice thicknesses, and measured vertical strain. In spring 1997 a similar, but more detailed, set of measurements was collected at the same measuring site, and vertical strain rates were found to vary non-uniformly with depth, with the largest values closest to the surface. Article in Journal/Newspaper Journal of Glaciology Natural Environment Research Council: NERC Open Research Archive Journal of Glaciology 48 163 566 574 |
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Natural Environment Research Council: NERC Open Research Archive |
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ftnerc |
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unknown |
topic |
Glaciology |
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Glaciology Gudmundsson, G. Hilmar Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland |
topic_facet |
Glaciology |
description |
During a motion event on Unteraargletscher, Bernese Alps, Switzerland, in spring 1996, surface velocities were measured up to eight times a day at four different locations along the central flowline using global positioning system equipment. In addition, accumulated vertical strains over the uppermost 50 and 100 m were measured at a location where the total ice thickness is 260 m. The motion event was accompanied by high horizontal and vertical strain rates as compared to annual mean values. A reversal in strain regime was observed, with horizontal strain rates changing to extension while vertical strain rates became compressive. This strain-rate reversal coincided, within the temporal resolution of the data, with a maximum in vertical ice displacement at the surface. Within a day, variations in vertical strain from 0.04 a(-1) to -0.06 a(-1) were observed over the uppermost 100 m. Vertical stretching is estimated to have contributed to at least 20% of the anomalous vertical ice movement at the surface. There were significant differences between measured longitudinal strain, averaged over a distance corresponding to a few ice thicknesses, and measured vertical strain. In spring 1997 a similar, but more detailed, set of measurements was collected at the same measuring site, and vertical strain rates were found to vary non-uniformly with depth, with the largest values closest to the surface. |
format |
Article in Journal/Newspaper |
author |
Gudmundsson, G. Hilmar |
author_facet |
Gudmundsson, G. Hilmar |
author_sort |
Gudmundsson, G. Hilmar |
title |
Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland |
title_short |
Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland |
title_full |
Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland |
title_fullStr |
Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland |
title_full_unstemmed |
Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland |
title_sort |
observations of a reversal in vertical and horizontal strain-rate regime during a motion event on unteraargletscher, bernese alps, switzerland |
publisher |
International Glaciological Society |
publishDate |
2002 |
url |
http://nora.nerc.ac.uk/id/eprint/13394/ http://www.ingentaconnect.com/content/igsoc/jog/2002/00000048/00000163/art00010 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_relation |
Gudmundsson, G. Hilmar orcid:0000-0003-4236-5369 . 2002 Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland. Journal of Glaciology, 48 (163). 566-574. https://doi.org/10.3189/172756502781831043 <https://doi.org/10.3189/172756502781831043> |
op_doi |
https://doi.org/10.3189/172756502781831043 |
container_title |
Journal of Glaciology |
container_volume |
48 |
container_issue |
163 |
container_start_page |
566 |
op_container_end_page |
574 |
_version_ |
1766049186684338176 |