Characterising sediment thickness beneath a Greenlandic outlet glacier using distributed acoustic sensing: preliminary observations and progress towards an efficient machine learning approach

Adam D. Booth*, Poul Christoffersen, Andrew Pretorius, Joseph Chapman, Bryn Hubbard, Emma C. Smith, Sjoerd de Ridder, Andy Nowacki, Bradley Paul Lipovsky, Marine Denolle

*Corresponding author for this work

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Abstract

Distributed Acoustic Sensing (DAS) is increasingly recognised as a valuable tool for glaciological seismic applications, although analysing the large data volumes generated in acquisitions poses computational challenges. We show the potential of active-source DAS to image and characterise subglacial sediment beneath a fast-flowing Greenlandic outlet glacier, estimating the thickness of sediment layers to be 20-30 m. However, the lack of subglacial velocity constraint limits the accuracy of this estimate. Constraint could be provided by analysing cryoseismic events in a counterpart 3-day record of passive seismicity through, for example, seismic tomography, but locating them within the 9 TB data volume is computationally inefficient. We describe experiments with data compression using the frequency-wavenumber (f-k) transform ahead of training a convolutional neural network, that provides a ∼300-fold improvement in efficiency. In combining active and passive-source and our machine learning framework, the potential of large DAS datasets could be unlocked for a range of future applications.

Original languageEnglish
Number of pages4
JournalAnnals of Glaciology
Volume63
Issue number87-89
DOIs
Publication statusPublished - 24 Apr 2023

Keywords

  • Anisotropic ice
  • arctic glaciology
  • glaciological instruments and methods
  • seismology
  • subglacial sediments

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