Mapping the Ice-Bed Interface Characteristics of Rutford Ice Stream, West Antarctica, Using Microseismicity

Smith, E. C. and Smith, A. M. and White, R. S. and Brisbourne, A. M. and Pritchard, H. D. (2015) Mapping the Ice-Bed Interface Characteristics of Rutford Ice Stream, West Antarctica, Using Microseismicity. Journal of Geophysical Research. ISSN 0148-0227 DOI 10.1002/2015JF003587

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Abstract

Flow dynamics of the ice streams which drain the Antarctic Ice Sheet are heavily in uenced by the processes happening at the bed. Natural seismic activity generated beneath an ice stream is associated with the motion of the ice over its bed and can be used to map the characteristics of the ice-bed interface and to understand these basal processes. Basal microseismicity was recorded over a 34-day period on Rutford Ice Stream, West Antarctica, using ten three-component geophones 40 km upstream of the grounding line. Around 3000 microseismic events were located in discrete spatial clusters near the ice-bed interface. The activity of each cluster varies with time, and the source mechanism for the events is interpreted as sub-horizontal, low-angle faulting, slipping in the ice ow direction. Cluster locations are interpreted as `sticky spots' of stiff basal sediment at the ice-bed interface, where ice movement is accommodated by stick-slip basal sliding. The `sticky spots' occur in areas where independent active-source seismic surveys show low porosity sediments at the bed. We show that the `sticky spots' probably accommodate only a small amount of the total basal motion. Our results suggest that most of the ice motion is accommodated by aseismic deformation of soft,dilatant basal sediment or by a well-lubricated, stiffer bed

Item Type: Article
Uncontrolled Keywords: 2014AREP; IA68; BAS; published
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 10 - Explosive Earth
Journal or Publication Title: Journal of Geophysical Research
Identification Number: 10.1002/2015JF003587
Depositing User: Sarah Humbert
Date Deposited: 25 Mar 2015 10:46
Last Modified: 22 Jun 2016 16:52
URI: http://eprints.esc.cam.ac.uk/id/eprint/3256

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