Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)

Glaciers are widely spread on polar and sub-polar regions but also on middle latitude mountains, where cold-dry type glaciers, polythermal glaciers and temperate-wet glaciers are respectively present. Polythermal glaciers have a cold-ice layer (temperature below the pressure melting point) overridin...

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Autor: Turu, Valentí
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2012
País:España
Institución:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
Repositorio:Recercat. Dipósit de la Recerca de Catalunya
OAI Identifier:oai:recercat.cat:2445/193378
Acceso en línea:https://hdl.handle.net/2445/193378
Access Level:acceso abierto
Palabra clave:Glaceres
Ressonància magnètica
Noruega
Glaciers
Magnetic resonance
Norway
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spelling Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)Turu, ValentíGlaceresRessonància magnèticaNoruegaGlaciersMagnetic resonanceNorwayGlaciers are widely spread on polar and sub-polar regions but also on middle latitude mountains, where cold-dry type glaciers, polythermal glaciers and temperate-wet glaciers are respectively present. Polythermal glaciers have a cold-ice layer (temperature below the pressure melting point) overriding a temperate-ice layer. Nineteen magnetic resonance soundings were done following a 3 Km profile on Hansbreen front. Resistivity on the glacier surface, magnetic susceptibility of rocks, electromagnetic noise and total earth's magnetic field measurements confirm that the MRS survey took place in the best conditions. MRS data show different signals amplitudes at the Larmor frequency according to the loop dimension. In a very high electrical resistive context (>2 Mega Ohms meter for glacier ice) the surveyed depth is directly related to the loop area. For small loops (30 m square loop) amplitudes around 50 nV are common as well as some decay time (T*2) above 300 ms. Enlarging the loop size (60 m square loop) it is possible to observe a decrease of the signal amplitude at the Larmor frequency (E0 < 20 nV) but also the time decay (100 ms >= T*2 >40 ms). Increasing loop sizes (90 and 120 m square loops), a slight increase in amplitude at the Larmor frequency, close to 30 nV, is observed with very high time decays (T*2 >500 ms). Ground Penetrating Radar surveys were carried out in Hansbreen at the same location as the MRS surveyed zone. Available GPR data show a water content of 2,5% on the cold-ice layer (the first 35 m depth) and 2% of water content on the temperate-ice layer but a 4% of water content can also be detected. Both geophysical methods are not convergent because some water content on ice has too short relaxation times being undetectable with conventional MRS devices. In that sense the low T*2 time decays data from large MRS loops elucidates that at the temperate-ice layer water flows by seepage through veins and microfractures at a very low rate toward the glacier bottom and a large amount of free water is close to the cold/temperate transition surface. In the cold-ice layer large T*2 time decays are common because water flows through fissures or karstic like conduits. In summary, combining the MRS and GPR techniques gives glaciologists a powerful toolkit to elucidate water flow-paths on glaciers, supercooled meltwater content and subglacial water or aquifers.Stowarzyszenie Geomorfologów Polskich2023202320122023info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersion18 p.application/pdfhttps://hdl.handle.net/2445/193378Articles publicats en revistes (Dinàmica de la Terra i l'Oceà)reponame:Recercat. Dipósit de la Recerca de Catalunyainstname:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)InglésReproducció del document publicat a: http://geoinfo.amu.edu.pl/sgp/LA/LA21/LA21_057-074.pdfLandform Analysis, 2012, vol. 21, p. 57-74cc-by-nc-nd (c) Turu, Valentí, 2012https://creativecommons.org/licenses/by-nc-nd/4.0/info:eu-repo/semantics/openAccessoai:recercat.cat:2445/1933782026-05-29T05:05:01Z
dc.title.none.fl_str_mv Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)
title Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)
spellingShingle Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)
Turu, Valentí
Glaceres
Ressonància magnètica
Noruega
Glaciers
Magnetic resonance
Norway
title_short Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)
title_full Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)
title_fullStr Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)
title_full_unstemmed Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)
title_sort Surface NMR survey on Hansbreen Glacier, Hornsund, SW Spitsbergen (Norway)
dc.creator.none.fl_str_mv Turu, Valentí
author Turu, Valentí
author_facet Turu, Valentí
author_role author
dc.subject.none.fl_str_mv Glaceres
Ressonància magnètica
Noruega
Glaciers
Magnetic resonance
Norway
topic Glaceres
Ressonància magnètica
Noruega
Glaciers
Magnetic resonance
Norway
description Glaciers are widely spread on polar and sub-polar regions but also on middle latitude mountains, where cold-dry type glaciers, polythermal glaciers and temperate-wet glaciers are respectively present. Polythermal glaciers have a cold-ice layer (temperature below the pressure melting point) overriding a temperate-ice layer. Nineteen magnetic resonance soundings were done following a 3 Km profile on Hansbreen front. Resistivity on the glacier surface, magnetic susceptibility of rocks, electromagnetic noise and total earth's magnetic field measurements confirm that the MRS survey took place in the best conditions. MRS data show different signals amplitudes at the Larmor frequency according to the loop dimension. In a very high electrical resistive context (>2 Mega Ohms meter for glacier ice) the surveyed depth is directly related to the loop area. For small loops (30 m square loop) amplitudes around 50 nV are common as well as some decay time (T*2) above 300 ms. Enlarging the loop size (60 m square loop) it is possible to observe a decrease of the signal amplitude at the Larmor frequency (E0 < 20 nV) but also the time decay (100 ms >= T*2 >40 ms). Increasing loop sizes (90 and 120 m square loops), a slight increase in amplitude at the Larmor frequency, close to 30 nV, is observed with very high time decays (T*2 >500 ms). Ground Penetrating Radar surveys were carried out in Hansbreen at the same location as the MRS surveyed zone. Available GPR data show a water content of 2,5% on the cold-ice layer (the first 35 m depth) and 2% of water content on the temperate-ice layer but a 4% of water content can also be detected. Both geophysical methods are not convergent because some water content on ice has too short relaxation times being undetectable with conventional MRS devices. In that sense the low T*2 time decays data from large MRS loops elucidates that at the temperate-ice layer water flows by seepage through veins and microfractures at a very low rate toward the glacier bottom and a large amount of free water is close to the cold/temperate transition surface. In the cold-ice layer large T*2 time decays are common because water flows through fissures or karstic like conduits. In summary, combining the MRS and GPR techniques gives glaciologists a powerful toolkit to elucidate water flow-paths on glaciers, supercooled meltwater content and subglacial water or aquifers.
publishDate 2012
dc.date.none.fl_str_mv 2012
2023
2023
2023
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/2445/193378
url https://hdl.handle.net/2445/193378
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv Reproducció del document publicat a: http://geoinfo.amu.edu.pl/sgp/LA/LA21/LA21_057-074.pdf
Landform Analysis, 2012, vol. 21, p. 57-74
dc.rights.none.fl_str_mv cc-by-nc-nd (c) Turu, Valentí, 2012
https://creativecommons.org/licenses/by-nc-nd/4.0/
info:eu-repo/semantics/openAccess
rights_invalid_str_mv cc-by-nc-nd (c) Turu, Valentí, 2012
https://creativecommons.org/licenses/by-nc-nd/4.0/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv 18 p.
application/pdf
dc.publisher.none.fl_str_mv Stowarzyszenie Geomorfologów Polskich
publisher.none.fl_str_mv Stowarzyszenie Geomorfologów Polskich
dc.source.none.fl_str_mv Articles publicats en revistes (Dinàmica de la Terra i l'Oceà)
reponame:Recercat. Dipósit de la Recerca de Catalunya
instname:Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
instname_str Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya)
reponame_str Recercat. Dipósit de la Recerca de Catalunya
collection Recercat. Dipósit de la Recerca de Catalunya
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,811543

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