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

Gua Adalgeirsdóttir, A. M. Smith, T. Murray, M. A. King, K. Makinson, K. W. Nicholls, A. E. Behar

Research output: Contribution to journalArticle

27 Scopus citations

Abstract

High-resolution surface velocity measurements and passive seismic observations from Rutford Ice Stream, West Antarctica, 40km 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 40km upstream from the grounding line of a large ice stream.

Original languageEnglish (US)
Pages (from-to)715-724
Number of pages10
JournalJournal of Glaciology
Volume54
Issue number187
DOIs
StatePublished - 2008

ASJC Scopus subject areas

  • Earth-Surface Processes

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