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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Published in:Journal of Glaciology
Main Author: Gudmundsson, Hilmar
Format: Article in Journal/Newspaper
Language:unknown
Published: International Glaciological Society 2002
Subjects:
Online Access:https://nrl.northumbria.ac.uk/id/eprint/38165/
https://doi.org/10.3189/172756502781831043
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spelling ftunivnorthumb:oai:nrl.northumbria.ac.uk:38165 2023-05-15T16:57:31+02:00 Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland Gudmundsson, Hilmar 2002 https://nrl.northumbria.ac.uk/id/eprint/38165/ https://doi.org/10.3189/172756502781831043 unknown International Glaciological Society Gudmundsson, Hilmar (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). pp. 566-574. ISSN 0022-1430 F800 Physical and Terrestrial Geographical and Environmental Sciences Article PeerReviewed 2002 ftunivnorthumb https://doi.org/10.3189/172756502781831043 2022-09-25T06:09:19Z 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 Northumbria University, Newcastle: Northumbria Research Link (NRL) Journal of Glaciology 48 163 566 574
institution Open Polar
collection Northumbria University, Newcastle: Northumbria Research Link (NRL)
op_collection_id ftunivnorthumb
language unknown
topic F800 Physical and Terrestrial Geographical and Environmental Sciences
spellingShingle F800 Physical and Terrestrial Geographical and Environmental Sciences
Gudmundsson, Hilmar
Observations of a reversal in vertical and horizontal strain-rate regime during a motion event on Unteraargletscher, Bernese Alps, Switzerland
topic_facet F800 Physical and Terrestrial Geographical and Environmental Sciences
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, Hilmar
author_facet Gudmundsson, Hilmar
author_sort Gudmundsson, 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 https://nrl.northumbria.ac.uk/id/eprint/38165/
https://doi.org/10.3189/172756502781831043
genre Journal of Glaciology
genre_facet Journal of Glaciology
op_relation Gudmundsson, Hilmar (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). pp. 566-574. ISSN 0022-1430
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
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