Crack wave resonances within the basal water layer
ABSTRACT Hydraulic processes within and beneath glacial bodies exert a far-reaching control on ice flow through their influence on basal sliding. Within the subglacial system, rapid changes in these processes may excite resonances whose interpretation requires an understanding of the underlying wave...
Published in: | Annals of Glaciology |
---|---|
Main Authors: | , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Cambridge University Press (CUP)
2019
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1017/aog.2019.8 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0260305519000089 |
id |
crcambridgeupr:10.1017/aog.2019.8 |
---|---|
record_format |
openpolar |
spelling |
crcambridgeupr:10.1017/aog.2019.8 2024-06-09T07:38:31+00:00 Crack wave resonances within the basal water layer Gräff, Dominik Walter, Fabian Lipovsky, Bradley P. 2019 http://dx.doi.org/10.1017/aog.2019.8 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0260305519000089 en eng Cambridge University Press (CUP) http://creativecommons.org/licenses/by-nc-sa/4.0/ Annals of Glaciology volume 60, issue 79, page 158-166 ISSN 0260-3055 1727-5644 journal-article 2019 crcambridgeupr https://doi.org/10.1017/aog.2019.8 2024-05-15T13:07:32Z ABSTRACT Hydraulic processes within and beneath glacial bodies exert a far-reaching control on ice flow through their influence on basal sliding. Within the subglacial system, rapid changes in these processes may excite resonances whose interpretation requires an understanding of the underlying wave mechanics. Here, we explore these mechanics using observations from a kHz-sampled pressure sensor installed in a borehole directly above the hard granite bedrock of a temperate mountain glacier in Switzerland. We apply a previously established theory of wave propagation along thin, water-filled structures such as water-filled voids, basal water layers, or hydraulic fractures. Within such structures, short-wavelength waves experience restoring forces due to compressibility and are composed of sound waves. Long-wavelength resonances, in contrast, experience restoring forces due to elasticity and are composed of anomalously dispersed crack waves or Krauklis waves. Our borehole observations confirm the occurrence of both sound and crack waves within the basal water layer. Using both the resonance frequencies and attenuation of recorded crack waves we estimate thickness, aperture and length of the resonating basal water layer patch into which we drilled. We demonstrate that high-frequency observations of subglacial hydraulic processes provide new insights into this evolving dynamic system. Article in Journal/Newspaper Annals of Glaciology Cambridge University Press Annals of Glaciology 60 79 158 166 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
description |
ABSTRACT Hydraulic processes within and beneath glacial bodies exert a far-reaching control on ice flow through their influence on basal sliding. Within the subglacial system, rapid changes in these processes may excite resonances whose interpretation requires an understanding of the underlying wave mechanics. Here, we explore these mechanics using observations from a kHz-sampled pressure sensor installed in a borehole directly above the hard granite bedrock of a temperate mountain glacier in Switzerland. We apply a previously established theory of wave propagation along thin, water-filled structures such as water-filled voids, basal water layers, or hydraulic fractures. Within such structures, short-wavelength waves experience restoring forces due to compressibility and are composed of sound waves. Long-wavelength resonances, in contrast, experience restoring forces due to elasticity and are composed of anomalously dispersed crack waves or Krauklis waves. Our borehole observations confirm the occurrence of both sound and crack waves within the basal water layer. Using both the resonance frequencies and attenuation of recorded crack waves we estimate thickness, aperture and length of the resonating basal water layer patch into which we drilled. We demonstrate that high-frequency observations of subglacial hydraulic processes provide new insights into this evolving dynamic system. |
format |
Article in Journal/Newspaper |
author |
Gräff, Dominik Walter, Fabian Lipovsky, Bradley P. |
spellingShingle |
Gräff, Dominik Walter, Fabian Lipovsky, Bradley P. Crack wave resonances within the basal water layer |
author_facet |
Gräff, Dominik Walter, Fabian Lipovsky, Bradley P. |
author_sort |
Gräff, Dominik |
title |
Crack wave resonances within the basal water layer |
title_short |
Crack wave resonances within the basal water layer |
title_full |
Crack wave resonances within the basal water layer |
title_fullStr |
Crack wave resonances within the basal water layer |
title_full_unstemmed |
Crack wave resonances within the basal water layer |
title_sort |
crack wave resonances within the basal water layer |
publisher |
Cambridge University Press (CUP) |
publishDate |
2019 |
url |
http://dx.doi.org/10.1017/aog.2019.8 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0260305519000089 |
genre |
Annals of Glaciology |
genre_facet |
Annals of Glaciology |
op_source |
Annals of Glaciology volume 60, issue 79, page 158-166 ISSN 0260-3055 1727-5644 |
op_rights |
http://creativecommons.org/licenses/by-nc-sa/4.0/ |
op_doi |
https://doi.org/10.1017/aog.2019.8 |
container_title |
Annals of Glaciology |
container_volume |
60 |
container_issue |
79 |
container_start_page |
158 |
op_container_end_page |
166 |
_version_ |
1801373465308037120 |