Seismic observations of a complex firn structure across the Amery Ice Shelf, East Antarctica
We use seismic refraction data to investigate the firn structure across a suture zone on the Amery Ice Shelf, East Antarctica, and the possible role of glacier dynamics in firn evolution. In the downstream direction, the data reveal decreasing compressional-wave velocities and increasing penetration...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Cambridge University Press
2021-10-01
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| Series: | Journal of Glaciology |
| Subjects: | |
| Online Access: | https://www.cambridge.org/core/product/identifier/S0022143021000216/type/journal_article |
| _version_ | 1827994394304708608 |
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| author | Hannes Hollmann Adam Treverrow Leo E. Peters Anya M. Reading Bernd Kulessa |
| author_facet | Hannes Hollmann Adam Treverrow Leo E. Peters Anya M. Reading Bernd Kulessa |
| author_sort | Hannes Hollmann |
| collection | DOAJ |
| description | We use seismic refraction data to investigate the firn structure across a suture zone on the Amery Ice Shelf, East Antarctica, and the possible role of glacier dynamics in firn evolution. In the downstream direction, the data reveal decreasing compressional-wave velocities and increasing penetration depth of the propagating wave in the firn layer, consistent with $\sim$1 m firn thickening every 6 km. The boundary between the Lambert Glacier unit to the west and a major suture zone and the Mawson Escarpment Ice Stream unit to the east, is marked by differences in firn thicknesses, compressional-wave velocities and seismic anisotropy in the across-flow direction. The latter does not contradict the presence of a single-maximum crystal orientation fabric oriented 45–$90^{\circ }$ away from the flow direction. This is consistent with the presence of transverse simple shear governing the region's underlying ice flow regime, in association with elevated strain along the suture zone. The confirmation and quantification of the implied dynamic coupling between firn and the underlying ice requires integration of future seismic refraction, coring and modelling studies. Because firn is estimated to cover $\sim$98% of the Antarctic continent any such coupling may have widespread relevance to ice-sheet evolution and flow. |
| first_indexed | 2024-04-10T04:39:13Z |
| format | Article |
| id | doaj.art-035ff35fdafa4be8acf5922e5ff11432 |
| institution | Directory Open Access Journal |
| issn | 0022-1430 1727-5652 |
| language | English |
| last_indexed | 2024-04-10T04:39:13Z |
| publishDate | 2021-10-01 |
| publisher | Cambridge University Press |
| record_format | Article |
| series | Journal of Glaciology |
| spelling | doaj.art-035ff35fdafa4be8acf5922e5ff114322023-03-09T12:41:09ZengCambridge University PressJournal of Glaciology0022-14301727-56522021-10-016777778710.1017/jog.2021.21Seismic observations of a complex firn structure across the Amery Ice Shelf, East AntarcticaHannes Hollmann0https://orcid.org/0000-0001-6113-1627Adam Treverrow1Leo E. Peters2Anya M. Reading3Bernd Kulessa4Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, AustraliaInstitute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, AustraliaSeismic Research Centre, University of the West Indies, St Augustine, Trinidad and TobagoSchool of Natural Sciences (Physics), University of Tasmania, Hobart, Tasmania, AustraliaCollege of Science, Swansea University, Swansea, UKWe use seismic refraction data to investigate the firn structure across a suture zone on the Amery Ice Shelf, East Antarctica, and the possible role of glacier dynamics in firn evolution. In the downstream direction, the data reveal decreasing compressional-wave velocities and increasing penetration depth of the propagating wave in the firn layer, consistent with $\sim$1 m firn thickening every 6 km. The boundary between the Lambert Glacier unit to the west and a major suture zone and the Mawson Escarpment Ice Stream unit to the east, is marked by differences in firn thicknesses, compressional-wave velocities and seismic anisotropy in the across-flow direction. The latter does not contradict the presence of a single-maximum crystal orientation fabric oriented 45–$90^{\circ }$ away from the flow direction. This is consistent with the presence of transverse simple shear governing the region's underlying ice flow regime, in association with elevated strain along the suture zone. The confirmation and quantification of the implied dynamic coupling between firn and the underlying ice requires integration of future seismic refraction, coring and modelling studies. Because firn is estimated to cover $\sim$98% of the Antarctic continent any such coupling may have widespread relevance to ice-sheet evolution and flow.https://www.cambridge.org/core/product/identifier/S0022143021000216/type/journal_articlePolar firnseismicssnow mechanics |
| spellingShingle | Hannes Hollmann Adam Treverrow Leo E. Peters Anya M. Reading Bernd Kulessa Seismic observations of a complex firn structure across the Amery Ice Shelf, East Antarctica Journal of Glaciology Polar firn seismics snow mechanics |
| title | Seismic observations of a complex firn structure across the Amery Ice Shelf, East Antarctica |
| title_full | Seismic observations of a complex firn structure across the Amery Ice Shelf, East Antarctica |
| title_fullStr | Seismic observations of a complex firn structure across the Amery Ice Shelf, East Antarctica |
| title_full_unstemmed | Seismic observations of a complex firn structure across the Amery Ice Shelf, East Antarctica |
| title_short | Seismic observations of a complex firn structure across the Amery Ice Shelf, East Antarctica |
| title_sort | seismic observations of a complex firn structure across the amery ice shelf east antarctica |
| topic | Polar firn seismics snow mechanics |
| url | https://www.cambridge.org/core/product/identifier/S0022143021000216/type/journal_article |
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