Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West Antarctica

Agnew, Ronan S. ORCID: https://orcid.org/0009-0000-3609-6815; Clark, Roger A.; Booth, Adam D.; Brisbourne, Alex M. ORCID: https://orcid.org/0000-0002-9887-7120; Smith, Andrew M. ORCID: https://orcid.org/0000-0001-8577-482X. 2023 Measuring seismic attenuation in polar firn: method and application to Korff Ice Rise, West Antarctica. Journal of Glaciology. 12, pp. https://doi.org/10.1017/jog.2023.82

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Abstract/Summary

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.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1017/jog.2023.82
ISSN:	0022-1430
Additional Keywords:	Glacier geophysics, glaciological instruments and methods, polar firn, seismics
Date made live:	31 Oct 2023 12:26 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/536191

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1017/jog.2023.82

ISSN:

0022-1430

Additional Keywords:

Glacier geophysics, glaciological instruments and methods, polar firn, seismics

Date made live:

31 Oct 2023 12:26 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/536191