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Tidal influence on Rutford Ice Stream, West Antarctica: observations of surface flow and basal processes from closely-spaced GPS and passive seismic stations

Lookup NU author(s): Professor Matt King

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Abstract

High-resolution surface velocity measurements and passive seismic observations from Rutford Ice Stream, West Antarctica, 40 km upstream from the grounding line are presented. These measurements indicate a complex relationship between the ocean tides and currents, basal conditions and ice-stream flow. Both the mean basal seismicity and the velocity of the ice stream are modulated by the tides. Seismic activity increases twice during each semi-diurnal tidal cycle. The tidal analysis shows the largest velocity variation is at the fortnightly period, with smaller variations superimposed at diurnal and semi-diurnal frequencies. The general pattern of the observed velocity is two velocity peaks during each semi-diurnal tidal cycle, but sometimes three peaks are observed. This pattern of two or three peaks is more regular during spring tides, when the largest-amplitude velocity variations are observed, than during neap tides. This is the first time that velocity and level of seismicity are shown to correlate and respond to tidal forcing as far as 40 km upstream from the grounding line of a large ice stream.

Publication metadata

Author(s): Aðalgeirsdóttir G, Murray T, Smith A, King MA, Makinson K, Nicholls K, Behar A

Publication type: Article

Publication status: Published

Journal: Journal of Glaciology

Year: 2008

Volume: 54

Issue: 187

Pages: 715-724

ISSN (print): 0022-1430

ISSN (electronic): 1727-5652

Publisher: International Glaciological Society

URL: http://dx.doi.org/10.3189/002214308786570872

DOI: 10.3189/002214308786570872

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