02273nas a2200205   4500008004100000022001400041245012200055210006900177260001200246490000800258520159800266653001401864653001901878653002201897653001901919100002001938700002701958700002101985856006102006       2022                        eng d  a2169-900300aWintertime brine discharge at the surface of a cold polar glacier and the unexpected absence of associated seismicity0 aWintertime brine discharge at the surface of a cold polar glacie  c03/20220 v1273 a<p>A subglacial groundwater system beneath Taylor Glacier, Antarctica, 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. Identifying which fracture processes are observed seismically can help us better characterize the hydrological system at Taylor Glacier, and more generally, provide us with a broader understanding of englacial hydrologic activity in cold glaciers. We document wintertime brine discharge using time-lapse photography. Subfreezing air temperatures during the brine discharge indicate that surface melt-induced hydrofracture is an unlikely trigger for brine release. 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.</p>10acrevasses10acryoseismology10aglacier hydrology10aRayleigh waves1 aCarr, Chris, G.1 aCarmichael, Joshua, D.1 aPettit, Erin, C.  uhttps://onlinelibrary.wiley.com/doi/10.1029/2021JF00632502262nas a2200145   4500008004100000245013600041210006900177260001200246520154000258100002001798700002301818700002101841700002001862856023401882       2020                        eng d00aThe influence of environmental microseismicity on detection and interpretation of small-magnitude events in a polar glacier setting0 ainfluence of environmental microseismicity on detection and inte  c07/20203 a<p>Glacial environments exhibit temporally variable microseismicity. To investigate how microseismicity influences event detection, we implement two noise-adaptive digital power detectors to process seismic data from Taylor Glacier, Antarctica. We add scaled icequake waveforms to the original data stream, run detectors on the hybrid data stream to estimate reliable detection magnitudes and compare analytical magnitudes predicted from an ice crack source model. We find that detection capability is influenced by environmental microseismicity for seismic events with source size comparable to thermal penetration depths. When event counts and minimum detectable event sizes change in the same direction (i.e. increase in event counts and minimum detectable event size), we interpret measured seismicity changes as &lsquo;true&rsquo; seismicity changes rather than as changes in detection. Generally, one detector (two degree of freedom (2dof)) outperforms the other: it identifies more events, a more prominent summertime diurnal signal and maintains a higher detection capability. We conclude that real physical processes are responsible for the summertime diurnal inter-detector difference. One detector (3dof) identifies this process as environmental microseismicity; the other detector (2dof) identifies it as elevated waveform activity. Our analysis provides an example for minimizing detection biases and estimating source sizes when interpreting temporal seismicity patterns to better infer glacial seismogenic processes.</p>1 aCarr, Chris, G.1 aCarmichael, J., D.1 aPettit, Erin, C.1 aTruffer, Martin  uhttps://www.cambridge.org/core/journals/journal-of-glaciology/article/influence-of-environmental-microseismicity-on-detection-and-interpretation-of-smallmagnitude-events-in-a-polar-glacier-setting/E1A441425341F677117509351F3C6763