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Subglacial discharge at tidewater glaciers revealed by seismic tremor

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Full Publication: http://dx.doi.org/10.1002/2015GL064590

Product Type: Journal Article

Year: 2015

Authors: Bartholomaus, T. C., J. M. Amundson, J. I. Walter, S. R. O'Neel, M. E. West, and C. F. Larsen


Suggested Citation:
Bartholomaus, T. C., J. M. Amundson, J. I. Walter, S. R. O'Neel, M. E. West, and C. F. Larsen. 2015. Subglacial discharge at tidewater glaciers revealed by seismic tremor. Geophysical Research Letters 42:6391-6398. doi:10.1002/2015GL064590

Abstract


Subglacial discharge influences glacier basal motion and erodes and redeposits sediment. At tidewater glacier termini, discharge drives submarine terminus melting, affects fjord circulation, and is a central component of proglacial marine ecosystems. However, our present inability to track subglacial discharge and its variability significantly hinders our understanding of these processes. Here we report observations of hourly to seasonal variations in 1.5–10Hz seismic tremor that strongly correlate with subglacial discharge but not with basal motion, weather, or discrete icequakes. Our data demonstrate that vigorous discharge occurs from tidewater glaciers during summer, in spite of fast basal motion that could limit the formation of subglacial conduits, and then abates during winter. Furthermore, tremor observations and a melt model demonstrate that drainage efficiency of tidewater glaciers evolves seasonally. Glaciohydraulic tremor provides a means by which to quantify subglacial discharge variations and offers a promising window into otherwise obscured glacierized environments.

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