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Distributed Acoustic Sensing (DAS) for natural microseismicity studies: A case study from Antarctica
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  • Thomas Samuel Hudson,
  • Alan F Baird,
  • John-Michael Kendall,
  • Sofia-Katerina Kufner,
  • Alex Mark Brisbourne,
  • Andrew Mark Smith,
  • Antony Butcher,
  • Athena Chalari,
  • Andy Clarke
Thomas Samuel Hudson
University of Oxford

Corresponding Author:[email protected]

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Alan F Baird
NORSAR
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John-Michael Kendall
University of Oxford
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Sofia-Katerina Kufner
British Antarctic Survey
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Alex Mark Brisbourne
British Antarctic Survey
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Andrew Mark Smith
British Antarctic Survey
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Antony Butcher
University of Bristol
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Athena Chalari
Silixa Ltd.
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Andy Clarke
Silixa Ltd.
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Abstract

Icequakes, microseismic earthquakes at glaciers, offer critical insights into the dynamics of ice sheets. For the first time in the Antarctic, we explore the use of fibre optic cables as Distributed Acoustic Sensors (DAS) as a new approach for monitoring basal icequakes. Fibre was deployed on the ice surface at Rutford Ice Stream, in two different configurations. We compare the performance of DAS with a conventional geophone network for: microseismic detection and location; resolving source and noise spectra; source mechanism inversion; and measuring anisotropic shear-wave splitting parameters. The DAS arrays detect fewer events than the geophone array. However, DAS is superior to geophones for recording the microseism signal, suggesting the applicability of DAS for ambient noise interferometry. We also present the first full-waveform source mechanism inversions using DAS anywhere, successfully constraining the horizontal stick-slip nature of the icequakes. In addition, we develop an approach to use a 2D DAS array geometry as an effective multi-component sensor capable of accurately characterising shear-wave splitting due to anisotropy of the ice fabric. Although our observations originate from a glacial environment, the methodology and implications of this work are relevant for employing DAS in other microseismic environments.
Jul 2021Published in Journal of Geophysical Research: Solid Earth volume 126 issue 7. 10.1029/2020JB021493