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Seismicity on the western Greenland Ice Sheet: surface fracture in the vicinity of active moulins


Carmichael, JD and Joughin, I and Behn, MD and Das, S and King, MA and Stevens, L and Lizarralde, D, Seismicity on the western Greenland Ice Sheet: surface fracture in the vicinity of active moulins, Journal of Geophysical Research: Earth Surface, 120, (6) pp. 1082-1106. ISSN 2169-9003 (2015) [Refereed Article]


Copyright Statement

2015. American Geophysical Union

DOI: doi:10.1002/2014JF003398


We analyzed geophone and GPS measurements collected within the ablation zone of the western Greenland Ice Sheet during a ~35 day period of the 2011 melt season to study changes in ice deformation before, during, and after a supraglacial lake drainage event. During rapid lake drainage, ice flow speeds increased to ~400% of winter values, and icequake activity peaked. At times >7 days after drainage, this seismicity developed variability over both diurnal and longer periods (~10 days), while coincident ice speeds fell to ~150% of winter values and showed nightly peaks in spatial variability. Approximately 95% of all detected seismicity in the lake basin and its immediate vicinity was triggered by fracture propagation within near-surface ice (<330m deep) that generated Rayleigh waves. Icequakes occurring before and during drainage frequently were collocated with the down flow (west) end of the primary hydrofracture through which the lake drained but shifted farther west and outside the lake basin after the drainage. We interpret these results to reveal vertical hydrofracture opening and local uplift during the drainage, followed by enhanced seismicity and ice flow on the downstream side of the lake basin. This region collocates with interferometric synthetic aperture radar-measured speedup in previous years and could reflect the migration path of themeltwater supplied to the bed by the lake. The diurnal seismic signal can be associated with nightly reductions in surface melt input that increase effective basal pressure and traction, thereby promoting elevated strain in the surficial ice.

Item Details

Item Type:Refereed Article
Keywords:Greenland, supraglacial lakes, GPS, seismology
Research Division:Earth Sciences
Research Group:Geophysics
Research Field:Geodesy
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the environmental sciences
UTAS Author:King, MA (Professor Matt King)
ID Code:101688
Year Published:2015
Funding Support:Australian Research Council (FT110100207)
Web of Science® Times Cited:28
Deposited By:Geography and Environmental Studies
Deposited On:2015-06-30
Last Modified:2017-10-24
Downloads:218 View Download Statistics

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