Seismic Tremor Reveals Spatial Organization and Temporal Changes of Subglacial Water System
©2019. American Geophysical Union. All Rights Reserved. Subglacial water flow impacts glacier dynamics and shapes the subglacial environment. However, due to the challenges of observing glacier beds, the spatial organization of subglacial water systems and the time scales of conduit evolution and mig...
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ftunivalaska:oai:scholarworks.alaska.edu:11122/10936 2023-05-15T16:20:32+02:00 Seismic Tremor Reveals Spatial Organization and Temporal Changes of Subglacial Water System Vore, Margot E. Bartholomaus, Timothy, C. Winberry, J. Paul Walter, Jacob I. Amundson, Jason M. 2019-02-09 http://hdl.handle.net/11122/10936 en_US eng American Geophysical Union Vore, M. E., Bartholomaus, T. C., Winberry, J. P., Walter, J. I., & Amundson, J. M. (2019). Seismic tremor reveals spatial organization and temporal changes of subglacial water system. Journal of Geophysical Research: Earth Surface, 124, 427–446. https://doi.org/10.1029/2018JF004819 http://hdl.handle.net/11122/10936 Journal of Geophysical Research: Earth Surface Research Article subglacial environment glacier dynamics conduit evolution glaciohydraulic subglacial polarization analysis Taku Glacier seismic tremor conduit flow path subglacial hydrologic system subglacial discharge glacier beds melt‐water input tremor frequencies delta‐like flow gradients vertical ground motion Article 2019 ftunivalaska 2023-02-23T21:37:35Z ©2019. American Geophysical Union. All Rights Reserved. Subglacial water flow impacts glacier dynamics and shapes the subglacial environment. However, 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 largely unknown. To address these questions, we analyze 1.5‐ to 10‐Hz seismic tremor that we associate with subglacial water flow, that is, glaciohydraulic tremor, at Taku Glacier, Alaska, throughout the 2016 melt season. We use frequency‐dependent polarization analysis to estimate glaciohydraulic tremor propagation direction (related to the subglacial conduit location) and a degree day melt model to monitor variations in melt‐water input. We suggest that conduit formation requires sustained water input and that multiconduit flow paths can be distinguished from single‐conduit flow paths. Theoretical analysis supports our seismic interpretations that subglacial discharge likely flows through a single‐conduit in regions of steep hydraulic potential gradients but may be distributed among multiple conduits in regions with shallower potential gradients. Seismic tremor in regions with multiple conduits evolves through abrupt jumps between stable configurations that last 3–7 days, while tremor produced by single‐conduit flow remains more stationary. We also find that polarized glaciohydraulic tremor wave types are potentially linked to the distance from source to station and that multiple peak frequencies propagate from a similar direction. Tremor appears undetectable at distances beyond 2–6 km from the source. This new understanding of the spatial organization and temporal development of subglacial conduits informs our understanding of dynamism within the subglacial hydrologic system. Raw seismic data described in this paper are available through the Incorporated Research Institutions for Seismology Data Management Center (http://ds.iris.edu/mda/ZQ? timewindow=2015‐2016; Amundson et al., 2015). The raw weather data ... Article in Journal/Newspaper glacier Alaska University of Alaska: ScholarWorks@UA Taku ENVELOPE(-133.854,-133.854,59.633,59.633) |
institution |
Open Polar |
collection |
University of Alaska: ScholarWorks@UA |
op_collection_id |
ftunivalaska |
language |
English |
topic |
subglacial environment glacier dynamics conduit evolution glaciohydraulic subglacial polarization analysis Taku Glacier seismic tremor conduit flow path subglacial hydrologic system subglacial discharge glacier beds melt‐water input tremor frequencies delta‐like flow gradients vertical ground motion |
spellingShingle |
subglacial environment glacier dynamics conduit evolution glaciohydraulic subglacial polarization analysis Taku Glacier seismic tremor conduit flow path subglacial hydrologic system subglacial discharge glacier beds melt‐water input tremor frequencies delta‐like flow gradients vertical ground motion Vore, Margot E. Bartholomaus, Timothy, C. Winberry, J. Paul Walter, Jacob I. Amundson, Jason M. Seismic Tremor Reveals Spatial Organization and Temporal Changes of Subglacial Water System |
topic_facet |
subglacial environment glacier dynamics conduit evolution glaciohydraulic subglacial polarization analysis Taku Glacier seismic tremor conduit flow path subglacial hydrologic system subglacial discharge glacier beds melt‐water input tremor frequencies delta‐like flow gradients vertical ground motion |
description |
©2019. American Geophysical Union. All Rights Reserved. Subglacial water flow impacts glacier dynamics and shapes the subglacial environment. However, 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 largely unknown. To address these questions, we analyze 1.5‐ to 10‐Hz seismic tremor that we associate with subglacial water flow, that is, glaciohydraulic tremor, at Taku Glacier, Alaska, throughout the 2016 melt season. We use frequency‐dependent polarization analysis to estimate glaciohydraulic tremor propagation direction (related to the subglacial conduit location) and a degree day melt model to monitor variations in melt‐water input. We suggest that conduit formation requires sustained water input and that multiconduit flow paths can be distinguished from single‐conduit flow paths. Theoretical analysis supports our seismic interpretations that subglacial discharge likely flows through a single‐conduit in regions of steep hydraulic potential gradients but may be distributed among multiple conduits in regions with shallower potential gradients. Seismic tremor in regions with multiple conduits evolves through abrupt jumps between stable configurations that last 3–7 days, while tremor produced by single‐conduit flow remains more stationary. We also find that polarized glaciohydraulic tremor wave types are potentially linked to the distance from source to station and that multiple peak frequencies propagate from a similar direction. Tremor appears undetectable at distances beyond 2–6 km from the source. This new understanding of the spatial organization and temporal development of subglacial conduits informs our understanding of dynamism within the subglacial hydrologic system. Raw seismic data described in this paper are available through the Incorporated Research Institutions for Seismology Data Management Center (http://ds.iris.edu/mda/ZQ? timewindow=2015‐2016; Amundson et al., 2015). The raw weather data ... |
format |
Article in Journal/Newspaper |
author |
Vore, Margot E. Bartholomaus, Timothy, C. Winberry, J. Paul Walter, Jacob I. Amundson, Jason M. |
author_facet |
Vore, Margot E. Bartholomaus, Timothy, C. Winberry, J. Paul Walter, Jacob I. Amundson, Jason M. |
author_sort |
Vore, Margot E. |
title |
Seismic Tremor Reveals Spatial Organization and Temporal Changes of Subglacial Water System |
title_short |
Seismic Tremor Reveals Spatial Organization and Temporal Changes of Subglacial Water System |
title_full |
Seismic Tremor Reveals Spatial Organization and Temporal Changes of Subglacial Water System |
title_fullStr |
Seismic Tremor Reveals Spatial Organization and Temporal Changes of Subglacial Water System |
title_full_unstemmed |
Seismic Tremor Reveals Spatial Organization and Temporal Changes of Subglacial Water System |
title_sort |
seismic tremor reveals spatial organization and temporal changes of subglacial water system |
publisher |
American Geophysical Union |
publishDate |
2019 |
url |
http://hdl.handle.net/11122/10936 |
long_lat |
ENVELOPE(-133.854,-133.854,59.633,59.633) |
geographic |
Taku |
geographic_facet |
Taku |
genre |
glacier Alaska |
genre_facet |
glacier Alaska |
op_source |
Research Article |
op_relation |
Vore, M. E., Bartholomaus, T. C., Winberry, J. P., Walter, J. I., & Amundson, J. M. (2019). Seismic tremor reveals spatial organization and temporal changes of subglacial water system. Journal of Geophysical Research: Earth Surface, 124, 427–446. https://doi.org/10.1029/2018JF004819 http://hdl.handle.net/11122/10936 Journal of Geophysical Research: Earth Surface |
_version_ |
1766008464865230848 |