Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion
Subglacial water modulates glacier-bed friction and therefore is of fundamental importance when characterising the dynamics of ice masses. The state of subglacial pore water, whether liquid or frozen, is associated with differences in electrical resistivity that span several orders of magnitude; hen...
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2020
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Online Access: | https://risweb.st-andrews.ac.uk/portal/en/researchoutput/characterisation-of-subglacial-water-using-a-constrained-transdimensional-bayesian-transient-electromagnetic-inversion(e4012ca9-800f-4311-bd50-89892c2552bb).html https://doi.org/10.5194/se-11-75-2020 https://research-repository.st-andrews.ac.uk/bitstream/10023/19347/1/Killingbeck_2020_SE_Subglacialwater_CC.pdf |
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ftunstandrewcris:oai:risweb.st-andrews.ac.uk:publications/e4012ca9-800f-4311-bd50-89892c2552bb 2023-05-15T16:37:53+02:00 Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion Killingbeck, S. F. Booth, A. D. Livermore, P. W. Bates, C. R. West, L. J. 2020-01-17 application/pdf https://risweb.st-andrews.ac.uk/portal/en/researchoutput/characterisation-of-subglacial-water-using-a-constrained-transdimensional-bayesian-transient-electromagnetic-inversion(e4012ca9-800f-4311-bd50-89892c2552bb).html https://doi.org/10.5194/se-11-75-2020 https://research-repository.st-andrews.ac.uk/bitstream/10023/19347/1/Killingbeck_2020_SE_Subglacialwater_CC.pdf eng eng info:eu-repo/semantics/openAccess Killingbeck , S F , Booth , A D , Livermore , P W , Bates , C R & West , L J 2020 , ' Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion ' , Solid Earth , vol. 11 , pp. 75-94 . https://doi.org/10.5194/se-11-75-2020 article 2020 ftunstandrewcris https://doi.org/10.5194/se-11-75-2020 2021-12-26T14:36:04Z Subglacial water modulates glacier-bed friction and therefore is of fundamental importance when characterising the dynamics of ice masses. The state of subglacial pore water, whether liquid or frozen, is associated with differences in electrical resistivity that span several orders of magnitude; hence, liquid water can be inferred from electrical resistivity depth profiles. Such profiles can be obtained from inversions of transient (time-domain) electromagnetic (TEM) soundings, but these are often non-unique. Here, we adapt an existing Bayesian transdimensional algorithm (Multimodal Layered Transdimensional Inversion – MuLTI) to the inversion of TEM data using independent depth constraints to provide statistical properties and uncertainty analysis of the resistivity profile with depth. The method was applied to ground-based TEM data acquired on the terminus of the Norwegian glacier, Midtdalsbreen, with depth constraints provided by co-located ground-penetrating radar data. Our inversion shows that the glacier bed is directly underlain by material of resistivity 10 2 Ωm ± 1000 %, with thickness 5–40 m, in turn underlain by a highly conductive basement (10 0 Ωm ± 15 %). High-resistivity material, 5×10 4 Ωm ± 25 %, exists at the front of the glacier. All uncertainties are defined by the interquartile range of the posterior resistivity distribution. Combining these resistivity profiles with those from co-located seismic shear-wave velocity inversions to further reduce ambiguity in the hydrogeological interpretation of the subsurface, we propose a new 3-D interpretation in which the Midtdalsbreen subglacial material is partitioned into partially frozen sediment, frozen sediment/permafrost and weathered/fractured bedrock with saline water. Article in Journal/Newspaper Ice permafrost University of St Andrews: Research Portal Solid Earth 11 1 75 94 |
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Open Polar |
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University of St Andrews: Research Portal |
op_collection_id |
ftunstandrewcris |
language |
English |
description |
Subglacial water modulates glacier-bed friction and therefore is of fundamental importance when characterising the dynamics of ice masses. The state of subglacial pore water, whether liquid or frozen, is associated with differences in electrical resistivity that span several orders of magnitude; hence, liquid water can be inferred from electrical resistivity depth profiles. Such profiles can be obtained from inversions of transient (time-domain) electromagnetic (TEM) soundings, but these are often non-unique. Here, we adapt an existing Bayesian transdimensional algorithm (Multimodal Layered Transdimensional Inversion – MuLTI) to the inversion of TEM data using independent depth constraints to provide statistical properties and uncertainty analysis of the resistivity profile with depth. The method was applied to ground-based TEM data acquired on the terminus of the Norwegian glacier, Midtdalsbreen, with depth constraints provided by co-located ground-penetrating radar data. Our inversion shows that the glacier bed is directly underlain by material of resistivity 10 2 Ωm ± 1000 %, with thickness 5–40 m, in turn underlain by a highly conductive basement (10 0 Ωm ± 15 %). High-resistivity material, 5×10 4 Ωm ± 25 %, exists at the front of the glacier. All uncertainties are defined by the interquartile range of the posterior resistivity distribution. Combining these resistivity profiles with those from co-located seismic shear-wave velocity inversions to further reduce ambiguity in the hydrogeological interpretation of the subsurface, we propose a new 3-D interpretation in which the Midtdalsbreen subglacial material is partitioned into partially frozen sediment, frozen sediment/permafrost and weathered/fractured bedrock with saline water. |
format |
Article in Journal/Newspaper |
author |
Killingbeck, S. F. Booth, A. D. Livermore, P. W. Bates, C. R. West, L. J. |
spellingShingle |
Killingbeck, S. F. Booth, A. D. Livermore, P. W. Bates, C. R. West, L. J. Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion |
author_facet |
Killingbeck, S. F. Booth, A. D. Livermore, P. W. Bates, C. R. West, L. J. |
author_sort |
Killingbeck, S. F. |
title |
Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion |
title_short |
Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion |
title_full |
Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion |
title_fullStr |
Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion |
title_full_unstemmed |
Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion |
title_sort |
characterisation of subglacial water using a constrained transdimensional bayesian transient electromagnetic inversion |
publishDate |
2020 |
url |
https://risweb.st-andrews.ac.uk/portal/en/researchoutput/characterisation-of-subglacial-water-using-a-constrained-transdimensional-bayesian-transient-electromagnetic-inversion(e4012ca9-800f-4311-bd50-89892c2552bb).html https://doi.org/10.5194/se-11-75-2020 https://research-repository.st-andrews.ac.uk/bitstream/10023/19347/1/Killingbeck_2020_SE_Subglacialwater_CC.pdf |
genre |
Ice permafrost |
genre_facet |
Ice permafrost |
op_source |
Killingbeck , S F , Booth , A D , Livermore , P W , Bates , C R & West , L J 2020 , ' Characterisation of subglacial water using a constrained transdimensional Bayesian transient electromagnetic inversion ' , Solid Earth , vol. 11 , pp. 75-94 . https://doi.org/10.5194/se-11-75-2020 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/se-11-75-2020 |
container_title |
Solid Earth |
container_volume |
11 |
container_issue |
1 |
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75 |
op_container_end_page |
94 |
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1766028176771776512 |