Abstract

This seminar will be held online. Details will be sent to the Earth Sciences and Bullard mailing lists. If you are not in Earth Sciences but would like to attend, please contact the talk organisers.

Distributed Acoustic Sensing (DAS) is a novel technology in which seismic energy 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 compressional and shear wave propagation in 1043 m-deep vertical seismic profiles, sampled at 10 m vertical resolution, we detected a transition from isotropic to anisotropic ice consistent with a Holocene-Wisconsin transition at 83% of the ice thickness. We also infer temperate ice in the lowermost 100 m of the glacier, and identified subglacial reflections originating from the base of a 20 m-thick layer of consolidated sediment. We also recorded time-lapse variations in glacier seismicity, using both repeat shots at zero-offset and monitoring the DAS cable (for 3 days) in a passive mode. We suggest that DAS has transformative potential for glaciological monitoring, and predict that it will be widely integrated as the cost of equipment progressively decreases.