Abstract
Subglacial water flow directly impacts glacier dynamics and shapes the subglacial environment. The subglacial water system changes in response to water that flows through conduits at the glacier’s bed, with a distributed, inefficient drainage system in the winter evolving into a channelized, efficient system during the melt season. Due to the challenges of observing glacier beds, the spatial organization of subglacial water systems and the time scales of conduit evolution and migration are unknown. To address these questions, I monitor seismic tremor produced by subglacial water flow, i.e. glaciohydraulic tremor, between 1.5 and 10 Hz throughout the 2016 melt season on Taku glacier. I use frequency dependent polarization analysis to estimate glaciohydraulic tremor propagation direction (which is a proxy for subglacial conduit location) and a degree day melt model to monitor trends of melt water input. This study reveals that conduit formation relies on sustained water input and that single conduit flow paths can be distinguished from multi-conduit flow paths. Seismic tremor from multi-conduit flow experiences multiday locational changes while tremor produced by single conduit flow remains more stationary. This study also provides insight into the frequency, propagation, and wave structure of glaciohydraulic tremor, with polarized glaciohydraulic tremor wave types potentially linked to the distance from source to station and multiple frequencies propagating from the same source direction with propagation constrained by a distance threshold. My findings clarify the development and spatial organization of subglacial water systems which may be applied in future studies to gain a better understanding of glacier sliding speeds and glacier dynamics.