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Wintertime Brine Discharge at the Surface of a Cold Polar Glacier and the Unexpected Absence of Associated Seismicity
  • Chris G Carr,
  • Joshua D Carmichael,
  • Erin Christine Pettit
Chris G Carr
Los Alamos National Laboratory, Los Alamos National Laboratory

Corresponding Author:[email protected]

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Joshua D Carmichael
Los Alamos National Laboratory (DOE), Los Alamos National Laboratory (DOE)
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Erin Christine Pettit
Oregon State University, Oregon State University
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Abstract

A subglacial groundwater system beneath Taylor Glacier discharges hypersaline, iron-rich brine episodically at the glacier surface to create Blood Falls; however, the triggering mechanism for these brine release events is not yet understood. We document wintertime brine discharge using time-lapse photography to show that the mechanism does not require melt-induced hydrofracture. Further, we analyze local seismic data to test a hypothesis that fracturing generates elevated surface wave energy preceding and/or coinciding with brine release events. Our results show no discernible elevated Rayleigh wave activity prior to or during Blood Falls brine release. Instead, we find a pattern of seismic events dominated by a seasonal signal, with more Rayleigh events occurring in the summer than the winter from the Blood Falls source area. We calculate that the volumetric opening of cracks that would generate Rayleigh waves at our detection limits are of similar size to myriad cracks in glacier ice, lake ice, and frozen sediment in the terminus area. We therefore propose that any fracturing coincident with brine release activity likely consists of a series of smaller opening events that are masked by other seismicity in the local environment.
Mar 2022Published in Journal of Geophysical Research: Earth Surface volume 127 issue 3. 10.1029/2021JF006325