Seismic Mapping of Subglacial Hydrology Reveals Previously Undetected Pressurization Event

• Published in: Journal of Geophysical Research: Earth Surface
• Main Authors: Labedz, Celeste R., Bartholomaus, Timothy C., Amundson, Jason M., Gimbert, Florent, Karplus, Marianne S., Tsai, Victor C., Veitch, Stephen A.
• Other Authors: Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: cryoseismology; environmental seismology; glacier hydrology; seismology; glaciology; [SDU]Sciences of the Universe [physics]; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Lemon Creek; Marginal Lake; glacier; glaciers; Alaska
• Online Access: https://insu.hal.science/insu-03706385; https://insu.hal.science/insu-03706385/document; https://insu.hal.science/insu-03706385/file/JGR%20Earth%20Surface%20-%202022%20-%20Labedz%20-%20Seismic%20Mapping%20of%20Subglacial%20Hydrology%20Reveals%20Previously%20Undetected%20Pressurization.pdf; https://doi.org/10.1029/2021JF006406

International audience Understanding the dynamic response of glaciers to climate change is vital for assessing water resources and hazards, and subglacial hydrology is a key player in glacier systems. Traditional observations of subglacial hydrology are spatially and temporally limited, but recent seismic deployments on and around glaciers show the potential for comprehensive observation of glacial hydrologic systems. We present results from a high-density seismic deployment spanning the surface of Lemon Creek Glacier, Alaska. Our study coincided with a marginal lake drainage event, which served as a natural experiment for seismic detection of changes in subglacial hydrology. We observed glaciohydraulic tremor across the surface of the glacier that was generated by the subglacial hydrologic system. During the lake drainage, the relative changes in seismic tremor power and water flux are consistent with pressurization of the subglacial system of only the upper part of the glacier. This event was not accompanied by a significant increase in glacier velocity; either some threshold necessary for rapid basal motion was not attained, or, plausibly, the geometry of Lemon Creek Glacier inhibited speedup. This pressurization event would have likely gone undetected without seismic observations, demonstrating the power of cryoseismology in testing assumptions about and mapping the spatial extent of subglacial pressurization.