Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes
Ice streams provide major drainage pathways for the Antarctic ice sheet. The stress distribution and style of flow in such ice streams produce elastic and rheological anisotropy, which informs ice-flow modelling as to how ice masses respond to external changes such as global warming. Here we analyse...
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ftnerc:oai:nora.nerc.ac.uk:502070 2023-05-15T13:29:47+02:00 Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes Harland, S.R. Kendall, J.-M. Stuart, G.W. Lloyd, G.E. Baird, A.F. Smith, A.M. Pritchard, H.D. Brisbourne, A.M. 2013-05 text http://nora.nerc.ac.uk/id/eprint/502070/ https://nora.nerc.ac.uk/id/eprint/502070/1/Harland%20et%20al%202013.pdf https://doi.org/10.3189/2013AoG64A033 en eng International Glaciological Society https://nora.nerc.ac.uk/id/eprint/502070/1/Harland%20et%20al%202013.pdf Harland, S.R.; Kendall, J.-M.; Stuart, G.W.; Lloyd, G.E.; Baird, A.F.; Smith, A.M. orcid:0000-0001-8577-482X Pritchard, H.D. orcid:0000-0003-2936-1734 Brisbourne, A.M. 2013 Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes. Annals of Glaciology, 54 (64). 105-114. https://doi.org/10.3189/2013AoG64A033 <https://doi.org/10.3189/2013AoG64A033> Publication - Article PeerReviewed 2013 ftnerc https://doi.org/10.3189/2013AoG64A033 2023-02-04T19:37:04Z Ice streams provide major drainage pathways for the Antarctic ice sheet. The stress distribution and style of flow in such ice streams produce elastic and rheological anisotropy, which informs ice-flow modelling as to how ice masses respond to external changes such as global warming. Here we analyse elastic anisotropy in Rutford Ice Stream, West Antarctica, using observations of shearwave splitting from three-component icequake seismograms to characterize ice deformation via crystalpreferred orientation. Over 110 high-quality measurements are made on 41 events recorded at five stations deployed temporarily near the ice-stream grounding line. To the best of our knowledge, this is the first well-documented observation of shear-wave splitting from Antarctic icequakes. The magnitude of the splitting ranges from 2 to 80ms and suggests a maximum of 6% shear-wave splitting. The fast shear-wave polarization direction is roughly perpendicular to ice-flow direction. We consider three mechanisms for ice anisotropy: a cluster model (vertical transversely isotropic (VTI) model); a girdle model (horizontal transversely isotropic (HTI) model); and crack-induced anisotropy (HTI model). Based on the data, we can rule out a VTI mechanism as the sole cause of anisotropy – an HTI component is needed, which may be due to ice crystal a-axis alignment in the direction of flow or the alignment of cracks or ice films in the plane perpendicular to the flow direction. The results suggest a combination of mechanisms may be at play, which represent vertical variations in the symmetry of ice crystal anisotropy in an ice stream, as predicted by ice fabric models. Article in Journal/Newspaper Annals of Glaciology Antarc* Antarctic Antarctica Ice Sheet Rutford Ice Stream West Antarctica Natural Environment Research Council: NERC Open Research Archive Antarctic The Antarctic West Antarctica Rutford ENVELOPE(-85.300,-85.300,-78.600,-78.600) Rutford Ice Stream ENVELOPE(-80.000,-80.000,-79.167,-79.167) Annals of Glaciology 54 64 105 114 |
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Open Polar |
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Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
English |
description |
Ice streams provide major drainage pathways for the Antarctic ice sheet. The stress distribution and style of flow in such ice streams produce elastic and rheological anisotropy, which informs ice-flow modelling as to how ice masses respond to external changes such as global warming. Here we analyse elastic anisotropy in Rutford Ice Stream, West Antarctica, using observations of shearwave splitting from three-component icequake seismograms to characterize ice deformation via crystalpreferred orientation. Over 110 high-quality measurements are made on 41 events recorded at five stations deployed temporarily near the ice-stream grounding line. To the best of our knowledge, this is the first well-documented observation of shear-wave splitting from Antarctic icequakes. The magnitude of the splitting ranges from 2 to 80ms and suggests a maximum of 6% shear-wave splitting. The fast shear-wave polarization direction is roughly perpendicular to ice-flow direction. We consider three mechanisms for ice anisotropy: a cluster model (vertical transversely isotropic (VTI) model); a girdle model (horizontal transversely isotropic (HTI) model); and crack-induced anisotropy (HTI model). Based on the data, we can rule out a VTI mechanism as the sole cause of anisotropy – an HTI component is needed, which may be due to ice crystal a-axis alignment in the direction of flow or the alignment of cracks or ice films in the plane perpendicular to the flow direction. The results suggest a combination of mechanisms may be at play, which represent vertical variations in the symmetry of ice crystal anisotropy in an ice stream, as predicted by ice fabric models. |
format |
Article in Journal/Newspaper |
author |
Harland, S.R. Kendall, J.-M. Stuart, G.W. Lloyd, G.E. Baird, A.F. Smith, A.M. Pritchard, H.D. Brisbourne, A.M. |
spellingShingle |
Harland, S.R. Kendall, J.-M. Stuart, G.W. Lloyd, G.E. Baird, A.F. Smith, A.M. Pritchard, H.D. Brisbourne, A.M. Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes |
author_facet |
Harland, S.R. Kendall, J.-M. Stuart, G.W. Lloyd, G.E. Baird, A.F. Smith, A.M. Pritchard, H.D. Brisbourne, A.M. |
author_sort |
Harland, S.R. |
title |
Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes |
title_short |
Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes |
title_full |
Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes |
title_fullStr |
Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes |
title_full_unstemmed |
Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes |
title_sort |
deformation in rutford ice stream, west antarctica: measuring shear-wave anisotropy from icequakes |
publisher |
International Glaciological Society |
publishDate |
2013 |
url |
http://nora.nerc.ac.uk/id/eprint/502070/ https://nora.nerc.ac.uk/id/eprint/502070/1/Harland%20et%20al%202013.pdf https://doi.org/10.3189/2013AoG64A033 |
long_lat |
ENVELOPE(-85.300,-85.300,-78.600,-78.600) ENVELOPE(-80.000,-80.000,-79.167,-79.167) |
geographic |
Antarctic The Antarctic West Antarctica Rutford Rutford Ice Stream |
geographic_facet |
Antarctic The Antarctic West Antarctica Rutford Rutford Ice Stream |
genre |
Annals of Glaciology Antarc* Antarctic Antarctica Ice Sheet Rutford Ice Stream West Antarctica |
genre_facet |
Annals of Glaciology Antarc* Antarctic Antarctica Ice Sheet Rutford Ice Stream West Antarctica |
op_relation |
https://nora.nerc.ac.uk/id/eprint/502070/1/Harland%20et%20al%202013.pdf Harland, S.R.; Kendall, J.-M.; Stuart, G.W.; Lloyd, G.E.; Baird, A.F.; Smith, A.M. orcid:0000-0001-8577-482X Pritchard, H.D. orcid:0000-0003-2936-1734 Brisbourne, A.M. 2013 Deformation in Rutford Ice Stream, West Antarctica: measuring shear-wave anisotropy from icequakes. Annals of Glaciology, 54 (64). 105-114. https://doi.org/10.3189/2013AoG64A033 <https://doi.org/10.3189/2013AoG64A033> |
op_doi |
https://doi.org/10.3189/2013AoG64A033 |
container_title |
Annals of Glaciology |
container_volume |
54 |
container_issue |
64 |
container_start_page |
105 |
op_container_end_page |
114 |
_version_ |
1766003010653126656 |