Distributed Acoustic Sensing (DAS) of Seismic Properties in a Borehole drilled on a Fast‐Flowing Greenlandic Outlet Glacier ...

• Main Authors: Booth, Adam D, Christoffersen, Poul, Schoonman, Charlotte, Clarke, Andy, Hubbard, Bryn, Law, Robert, Doyle, Samuel Huckerby, Chudley, Thomas Russell, Chalari, Athena
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley-Blackwell 2020
• Subjects: Distributed Acoustic Sensing DAS; Vertical Seismic Profile VSP; Greenland Ice Sheet; anisotropy; subglacial sediment; borehole surveying; Greenland; glacier; greenlandic; Ice Sheet
• Online Access: https://dx.doi.org/10.17863/cam.53990; https://www.repository.cam.ac.uk/handle/1810/306900

Distributed Acoustic Sensing (DAS) is a new technology in which seismic energy is detected, at high spatial and temporal resolution, using the propagation of laser pulses in a fibre-optic cable. We show analyses from the first glaciological borehole DAS deployment to measure the englacial and subglacial seismic properties of Store Glacier, a fast-flowing outlet of the Greenland Ice Sheet. We record compressional and shear waves in 1043 m-deep vertical seismic profiles, sampled at 10 m vertical resolution, and detect a transition from isotropic to anisotropic ice at 84% of ice thickness, consistent with the Holocene-Wisconsin transition. We identify subglacial reflections originating from the base of a 20 m-thick layer of consolidated sediment and, from attenuation measurements, interpret temperate ice in the lowermost 100 m of the glacier. Our findings highlight the promising potential of DAS technology to constrain the seismic properties of glaciers and ice sheets. ...