Active seismic studies in valley glacier settings: strategies and limitations
Subglacial tills play an important role in glacier dynamics but are difficult to characterize in situ. Amplitude Variation with Angle (AVA) analysis of seismic reflection data can distinguish between stiff tills and deformable tills. However, AVA analysis in mountain glacier environments can be prob...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Cambridge University Press
2018-10-01
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| Series: | Journal of Glaciology |
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| Online Access: | https://www.cambridge.org/core/product/identifier/S0022143018000692/type/journal_article |
| _version_ | 1827994417134305280 |
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| author | JENNA M. ZECHMANN ADAM D. BOOTH MARTIN TRUFFER ALESSIO GUSMEROLI JASON M. AMUNDSON CHRISTOPHER F. LARSEN |
| author_facet | JENNA M. ZECHMANN ADAM D. BOOTH MARTIN TRUFFER ALESSIO GUSMEROLI JASON M. AMUNDSON CHRISTOPHER F. LARSEN |
| author_sort | JENNA M. ZECHMANN |
| collection | DOAJ |
| description | Subglacial tills play an important role in glacier dynamics but are difficult to characterize in situ. Amplitude Variation with Angle (AVA) analysis of seismic reflection data can distinguish between stiff tills and deformable tills. However, AVA analysis in mountain glacier environments can be problematic: reflections can be obscured by Rayleigh wave energy scattered from crevasses, and complex basal topography can impede the location of reflection points in 2-D acquisitions. We use a forward model to produce challenging synthetic seismic records in order to test the efficacy of AVA in crevassed and geometrically complex environments. We find that we can distinguish subglacial till types in moderately crevassed environments, where ‘moderate’ depends on crevasse spacing and orientation. The forward model serves as a planning tool, as it can predict AVA success or failure based on characteristics of the study glacier. Applying lessons from the forward model, we perform AVA on a seismic dataset collected from Taku Glacier in Southeast Alaska in March 2016. Taku Glacier is a valley glacier thought to overlay thick sediment deposits. A near-offset polarity reversal confirms that the tills are deformable. |
| first_indexed | 2024-04-10T04:40:40Z |
| format | Article |
| id | doaj.art-5579d31274894f3d82efdfda04cb6b6b |
| institution | Directory Open Access Journal |
| issn | 0022-1430 1727-5652 |
| language | English |
| last_indexed | 2024-04-10T04:40:40Z |
| publishDate | 2018-10-01 |
| publisher | Cambridge University Press |
| record_format | Article |
| series | Journal of Glaciology |
| spelling | doaj.art-5579d31274894f3d82efdfda04cb6b6b2023-03-09T12:40:39ZengCambridge University PressJournal of Glaciology0022-14301727-56522018-10-016479681010.1017/jog.2018.69Active seismic studies in valley glacier settings: strategies and limitationsJENNA M. ZECHMANN0ADAM D. BOOTH1MARTIN TRUFFER2https://orcid.org/0000-0001-8251-7043ALESSIO GUSMEROLI3JASON M. AMUNDSON4CHRISTOPHER F. LARSEN5Geophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USAInstitute of Applied Geoscience, School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UKGeophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USAGeophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USAUniversity of Alaska Southeast, Juneau, AK, USAGeophysical Institute, University of Alaska Fairbanks, Fairbanks, AK, USASubglacial tills play an important role in glacier dynamics but are difficult to characterize in situ. Amplitude Variation with Angle (AVA) analysis of seismic reflection data can distinguish between stiff tills and deformable tills. However, AVA analysis in mountain glacier environments can be problematic: reflections can be obscured by Rayleigh wave energy scattered from crevasses, and complex basal topography can impede the location of reflection points in 2-D acquisitions. We use a forward model to produce challenging synthetic seismic records in order to test the efficacy of AVA in crevassed and geometrically complex environments. We find that we can distinguish subglacial till types in moderately crevassed environments, where ‘moderate’ depends on crevasse spacing and orientation. The forward model serves as a planning tool, as it can predict AVA success or failure based on characteristics of the study glacier. Applying lessons from the forward model, we perform AVA on a seismic dataset collected from Taku Glacier in Southeast Alaska in March 2016. Taku Glacier is a valley glacier thought to overlay thick sediment deposits. A near-offset polarity reversal confirms that the tills are deformable.https://www.cambridge.org/core/product/identifier/S0022143018000692/type/journal_articleglacial tillsglacier geophysicsglaciological instruments and methodsseismicssubglacial sediments |
| spellingShingle | JENNA M. ZECHMANN ADAM D. BOOTH MARTIN TRUFFER ALESSIO GUSMEROLI JASON M. AMUNDSON CHRISTOPHER F. LARSEN Active seismic studies in valley glacier settings: strategies and limitations Journal of Glaciology glacial tills glacier geophysics glaciological instruments and methods seismics subglacial sediments |
| title | Active seismic studies in valley glacier settings: strategies and limitations |
| title_full | Active seismic studies in valley glacier settings: strategies and limitations |
| title_fullStr | Active seismic studies in valley glacier settings: strategies and limitations |
| title_full_unstemmed | Active seismic studies in valley glacier settings: strategies and limitations |
| title_short | Active seismic studies in valley glacier settings: strategies and limitations |
| title_sort | active seismic studies in valley glacier settings strategies and limitations |
| topic | glacial tills glacier geophysics glaciological instruments and methods seismics subglacial sediments |
| url | https://www.cambridge.org/core/product/identifier/S0022143018000692/type/journal_article |
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