Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research Letters

Seismology is increasingly used to infer the magnitude and direction of glacial ice flow. However, the effects of interstitial meltwater on seismic properties remain poorly constrained. Here, we extend previous studies on seismic anisotropy in temperate ices to consider the role of melt preferred or...

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Authors: Seltzer, Cassandra, Llorens, Maria-Gema, Cross, Andrew J.
Format: article
Status:Published version
Publication Date:2024
Country:España
Institution:Consejo Superior de Investigaciones Científicas (CSIC)
Repository:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/366178
Online Access:http://hdl.handle.net/10261/366178
Access Level:Open access
Keyword:Cryoseismology
Melt network orientation
Ice flow
Temperate ice
Seismic anisotropy
Ice microstructure
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spelling Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research LettersSeltzer, CassandraLlorens, Maria-GemaCross, Andrew J.CryoseismologyMelt network orientationIce flowTemperate iceSeismic anisotropyIce microstructureSeismology is increasingly used to infer the magnitude and direction of glacial ice flow. However, the effects of interstitial meltwater on seismic properties remain poorly constrained. Here, we extend previous studies on seismic anisotropy in temperate ices to consider the role of melt preferred orientation (MPO). We used the ELLE numerical toolbox to simulate microstructural shear deformation of temperate ice with variable MPO strength and orientation, and calculated the effective seismic properties of these numerical ice-melt aggregates. Our models demonstrate that even 3.5% melt volume is sufficient to rotate fast directions by up to 90 degrees, to increase Vp anisotropy by up to +110%, and to modify Vs anisotropy by -9 to +36%. These effects are especially prominent at strain rates >= 3.17 x 10-12 s-1. MPO may thus obscure the geophysical signatures of temperate ice flow in regions of rapid ice discharge, and is therefore pivotal for understanding ice mass loss. Ice on Earth is pulled toward the sea by gravity, contributing to global mean sea level rise. To better understand the flow, or movement, of ice at the continent scale, geophysical surveys are increasingly being used to measure the microscopic alignment ("fabric") of ice crystals, since ice with a strong fabric flows more readily. However, in temperate regions close to the ice melting point, melt pockets may also become aligned, creating additional macroscopic geophysical signatures. Here, we use numerical simulations to examine the combined effects of ice crystal fabric and melt alignment on the geophysical (seismic) properties of ice containing small amounts of melt. We show that melt can change the seismic fast direction (related to the inferred flow direction) of ice by up to 90 degrees, particularly as the volume of melt exceeds 3.5%, and that different melt orientations can either enhance or diminish the anisotropy-based estimates of flow that some studies use to predict ice mass loss. These effects are especially prominent in faster-flowing ice, highly relevant to ice mass loss in warming regions. Geophysical studies that do not account for melt orientation may therefore produce incorrect estimates of flow, leading to inaccuracies in future climate models. We used simulations of deforming temperate ice to show that the alignment of interstitial meltwater changes bulk seismic properties The amount of melt required to significantly modify seismic properties is at least 50% lower than previously reported Melt should be considered when using seismic and radar anisotropy to interpret viscous ice deformation and enhancementCS received support from the MathWorks MIT School of Science Fellowship. MGL acknowledges the “Consolidación Investigadora” Grant CNS3022-135819 funded by Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación/10.13039/501100011033 and EU NextGenerationEU/PRTR. AJC was supported by a National Science Foundation award, OPP-2317263.Peer reviewedAmerican Geophysical UnionMinisterio de Ciencia e Innovación (España)National Science Foundation (US)Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2024202420242024info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/366178reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación/10.13039http://dx.doi.org/10.1029/2024GL110131Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/3661782026-05-22T06:33:51Z
dc.title.none.fl_str_mv Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research Letters
title Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research Letters
spellingShingle Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research Letters
Seltzer, Cassandra
Cryoseismology
Melt network orientation
Ice flow
Temperate ice
Seismic anisotropy
Ice microstructure
title_short Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research Letters
title_full Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research Letters
title_fullStr Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research Letters
title_full_unstemmed Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research Letters
title_sort Meltwater Orientations Modify Seismic Anisotropy in Temperate IceGeophysical Research Letters
dc.creator.none.fl_str_mv Seltzer, Cassandra
Llorens, Maria-Gema
Cross, Andrew J.
author Seltzer, Cassandra
author_facet Seltzer, Cassandra
Llorens, Maria-Gema
Cross, Andrew J.
author_role author
author2 Llorens, Maria-Gema
Cross, Andrew J.
author2_role author
author
dc.contributor.none.fl_str_mv Ministerio de Ciencia e Innovación (España)
National Science Foundation (US)
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Cryoseismology
Melt network orientation
Ice flow
Temperate ice
Seismic anisotropy
Ice microstructure
topic Cryoseismology
Melt network orientation
Ice flow
Temperate ice
Seismic anisotropy
Ice microstructure
description Seismology is increasingly used to infer the magnitude and direction of glacial ice flow. However, the effects of interstitial meltwater on seismic properties remain poorly constrained. Here, we extend previous studies on seismic anisotropy in temperate ices to consider the role of melt preferred orientation (MPO). We used the ELLE numerical toolbox to simulate microstructural shear deformation of temperate ice with variable MPO strength and orientation, and calculated the effective seismic properties of these numerical ice-melt aggregates. Our models demonstrate that even 3.5% melt volume is sufficient to rotate fast directions by up to 90 degrees, to increase Vp anisotropy by up to +110%, and to modify Vs anisotropy by -9 to +36%. These effects are especially prominent at strain rates >= 3.17 x 10-12 s-1. MPO may thus obscure the geophysical signatures of temperate ice flow in regions of rapid ice discharge, and is therefore pivotal for understanding ice mass loss. Ice on Earth is pulled toward the sea by gravity, contributing to global mean sea level rise. To better understand the flow, or movement, of ice at the continent scale, geophysical surveys are increasingly being used to measure the microscopic alignment ("fabric") of ice crystals, since ice with a strong fabric flows more readily. However, in temperate regions close to the ice melting point, melt pockets may also become aligned, creating additional macroscopic geophysical signatures. Here, we use numerical simulations to examine the combined effects of ice crystal fabric and melt alignment on the geophysical (seismic) properties of ice containing small amounts of melt. We show that melt can change the seismic fast direction (related to the inferred flow direction) of ice by up to 90 degrees, particularly as the volume of melt exceeds 3.5%, and that different melt orientations can either enhance or diminish the anisotropy-based estimates of flow that some studies use to predict ice mass loss. These effects are especially prominent in faster-flowing ice, highly relevant to ice mass loss in warming regions. Geophysical studies that do not account for melt orientation may therefore produce incorrect estimates of flow, leading to inaccuracies in future climate models. We used simulations of deforming temperate ice to show that the alignment of interstitial meltwater changes bulk seismic properties The amount of melt required to significantly modify seismic properties is at least 50% lower than previously reported Melt should be considered when using seismic and radar anisotropy to interpret viscous ice deformation and enhancement
publishDate 2024
dc.date.none.fl_str_mv 2024
2024
2024
2024
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/366178
url http://hdl.handle.net/10261/366178
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv #PLACEHOLDER_PARENT_METADATA_VALUE#
info:eu-repo/grantAgreement/Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación/10.13039
http://dx.doi.org/10.1029/2024GL110131
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv American Geophysical Union
publisher.none.fl_str_mv American Geophysical Union
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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