Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West Antarctica
We present seismic measurements of the firn column at Korff Ice Rise, West Antarctica, including measurements of compressional-wave velocity and attenuation. We describe a modified spectral-ratio method of measuring the seismic quality factor (Q) based on analysis of diving waves, which, combined wi...
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| Language: | English |
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Cambridge University Press
2023-12-01
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| Series: | Journal of Glaciology |
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| Online Access: | https://www.cambridge.org/core/product/identifier/S0022143023000825/type/journal_article |
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| author | Ronan S. Agnew Roger A. Clark Adam D. Booth Alex M. Brisbourne Andrew M. Smith |
| author_facet | Ronan S. Agnew Roger A. Clark Adam D. Booth Alex M. Brisbourne Andrew M. Smith |
| author_sort | Ronan S. Agnew |
| collection | DOAJ |
| description | We present seismic measurements of the firn column at Korff Ice Rise, West Antarctica, including measurements of compressional-wave velocity and attenuation. We describe a modified spectral-ratio method of measuring the seismic quality factor (Q) based on analysis of diving waves, which, combined with a stochastic method of error propagation, enables us to characterise the attenuative structure of firn in greater detail than has previously been possible. Q increases from 56 ± 23 in the uppermost 12 m to 570 ± 450 between 55 and 77 m depth. We corroborate our method with consistent measurements obtained via primary reflection, multiple, source ghost, and critically refracted waves. Using the primary reflection and its ghost, we find Q = 53 ± 20 in the uppermost 20 m of firn. From the critical refraction, we find Q = 640 ± 400 at 90 m depth. Our method aids the understanding of the seismic structure of firn and benefits characterisation of deeper glaciological targets, providing an alternative means of correcting seismic reflection amplitudes in cases where conventional methods of Q correction may be impossible. |
| format | Article |
| id | doaj-art-efb2fcfefbc94316bcd2e42cfea08e73 |
| institution | OA Journals |
| issn | 0022-1430 1727-5652 |
| language | English |
| publishDate | 2023-12-01 |
| publisher | Cambridge University Press |
| record_format | Article |
| series | Journal of Glaciology |
| spelling | doaj-art-efb2fcfefbc94316bcd2e42cfea08e732025-08-20T01:59:01ZengCambridge University PressJournal of Glaciology0022-14301727-56522023-12-01692075208610.1017/jog.2023.82Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West AntarcticaRonan S. Agnew0https://orcid.org/0009-0000-3609-6815Roger A. Clark1Adam D. Booth2Alex M. Brisbourne3https://orcid.org/0000-0002-9887-7120Andrew M. Smith4https://orcid.org/0000-0001-8577-482XSchool of Earth and Environment, University of Leeds, Leeds, UK NERC British Antarctic Survey, Cambridge, UKSchool of Earth and Environment, University of Leeds, Leeds, UKSchool of Earth and Environment, University of Leeds, Leeds, UKNERC British Antarctic Survey, Cambridge, UKNERC British Antarctic Survey, Cambridge, UKWe present seismic measurements of the firn column at Korff Ice Rise, West Antarctica, including measurements of compressional-wave velocity and attenuation. We describe a modified spectral-ratio method of measuring the seismic quality factor (Q) based on analysis of diving waves, which, combined with a stochastic method of error propagation, enables us to characterise the attenuative structure of firn in greater detail than has previously been possible. Q increases from 56 ± 23 in the uppermost 12 m to 570 ± 450 between 55 and 77 m depth. We corroborate our method with consistent measurements obtained via primary reflection, multiple, source ghost, and critically refracted waves. Using the primary reflection and its ghost, we find Q = 53 ± 20 in the uppermost 20 m of firn. From the critical refraction, we find Q = 640 ± 400 at 90 m depth. Our method aids the understanding of the seismic structure of firn and benefits characterisation of deeper glaciological targets, providing an alternative means of correcting seismic reflection amplitudes in cases where conventional methods of Q correction may be impossible.https://www.cambridge.org/core/product/identifier/S0022143023000825/type/journal_articleGlacier geophysicsglaciological instruments and methodspolar firnseismics |
| spellingShingle | Ronan S. Agnew Roger A. Clark Adam D. Booth Alex M. Brisbourne Andrew M. Smith Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West Antarctica Journal of Glaciology Glacier geophysics glaciological instruments and methods polar firn seismics |
| title | Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West Antarctica |
| title_full | Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West Antarctica |
| title_fullStr | Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West Antarctica |
| title_full_unstemmed | Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West Antarctica |
| title_short | Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West Antarctica |
| title_sort | measuring seismic attenuation in polar firn method and application to korff ice rise west antarctica |
| topic | Glacier geophysics glaciological instruments and methods polar firn seismics |
| url | https://www.cambridge.org/core/product/identifier/S0022143023000825/type/journal_article |
| work_keys_str_mv | AT ronansagnew measuringseismicattenuationinpolarfirnmethodandapplicationtokorfficerisewestantarctica AT rogeraclark measuringseismicattenuationinpolarfirnmethodandapplicationtokorfficerisewestantarctica AT adamdbooth measuringseismicattenuationinpolarfirnmethodandapplicationtokorfficerisewestantarctica AT alexmbrisbourne measuringseismicattenuationinpolarfirnmethodandapplicationtokorfficerisewestantarctica AT andrewmsmith measuringseismicattenuationinpolarfirnmethodandapplicationtokorfficerisewestantarctica |