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SUMMARY:Fantastic Fibre-Optics! Applications of distributed acoustic sensi
 ng in glaciology [Rescheduled to online] - Dr. Adam Booth\, University of 
 Leeds
DTSTART:20200617T110000Z
DTEND:20200617T120000Z
UID:TALK142030@talks.cam.ac.uk
CONTACT:Camilla Penney
DESCRIPTION:*This seminar will be held online. Details will be sent to the
  Earth Sciences and Bullard mailing lists. If you are not in Earth Science
 s but would like to attend\, please contact the talk organisers.*\n\nDistr
 ibuted Acoustic Sensing (DAS) is a novel technology in which seismic energ
 y is recorded at high spatial and temporal resolution along a fibre-optic 
 cable. We show analyses from a glaciological borehole deployment of DAS to
  measure the englacial and subglacial seismic properties of Store Glacier\
 , a fast-flowing outlet of the Greenland Ice Sheet. By characterising comp
 ressional and shear wave propagation in 1043 m-deep vertical seismic profi
 les\, sampled at 10 m vertical resolution\, we detected a transition from 
 isotropic to anisotropic ice consistent with a Holocene-Wisconsin transiti
 on at 83% of the ice thickness. We also infer temperate ice in the lowermo
 st 100 m of the glacier\, and identified subglacial reflections originatin
 g from the base of a 20 m-thick layer of consolidated sediment. We also re
 corded time-lapse variations in glacier seismicity\, using both repeat sho
 ts at zero-offset and monitoring the DAS cable (for 3 days) in a passive m
 ode. We suggest that DAS has transformative potential for glaciological mo
 nitoring\, and predict that it will be widely integrated as the cost of eq
 uipment progressively decreases. 
LOCATION:ONLINE - Details to be sent by email
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