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Abstract The grounding zone of a marine-terminating glacier, where ice begins to float, is a key control on glacier stability and ice discharge. Seismic deployments are a powerful means of studying both the geometry and processes of grounding zones; however, these regions are frequently inaccessible and dangerous for field work, and as a result are underrepresented in field studies. We report new data sets acquired at Eastwind Glacier, Antarctica, a relatively accessible grounding zone near McMurdo Station and Scott Base, as part of the Eastwind Glacier Geophysical Surveys on Top of an Antarctic Ice Shelf Transition, EGGS on TOAST, project. These data sets comprise a deployment of three-component seismic nodes and distributed acoustic sensing. The nodal deployment consisted of 330 nodes crossing the grounding zone, with all 330 nodes continuously recording for at least nine days, and 150 nodes recording for 19 days, in the austral summer of 2022/2023. Hammer-and-plate sources were recorded, with densely spaced shots along flow through the center of the array and shots located at every node. In 2023/2024, a 2.2 km fiber-optic cable was deployed for active source imaging by distributed acoustic sensing along and across flow, immediately downstream of the grounding line, for a period of 2 hr. Analysis of active source data recorded by the nodal array locates the point of flotation within the grounding zone and provides ice thickness estimates. We present initial analyses of passive source data, including icequake detection and location, and ambient noise analysis. We expect this data set to be of significant value to provide insight into fundamental grounding zone processes and as an event-rich cryoseismological data set on which to test novel methods of seismic analysis.
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Signal characteristics of surface seismic explosive sources near the West Antarctic Ice Sheet divide
Abstract Seismic imaging in 3-D holds great potential for improving our understanding of ice sheet structure and dynamics. Conducting 3-D imaging in remote areas is simplified by using lightweight and logistically straightforward sources. We report results from controlled seismic source tests carried out near the West Antarctic Ice Sheet Divide investigating the characteristics of two types of surface seismic sources, Poulter shots and detonating cord, for use in both 2-D and 3-D seismic surveys on glaciers. Both source types produced strong basal P-wave and S-wave reflections and multiples recorded in three components. The Poulter shots had a higher amplitude for low frequencies (<10 Hz) and comparable amplitude at high frequencies (>50 Hz) relative to the detonating cord. Amplitudes, frequencies, speed of source set-up, and cost all suggested Poulter shots to be the preferred surface source compared to detonating cord for future 2-D and 3-D seismic surveys on glaciers.
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- Award ID(s):
- 1739027
- PAR ID:
- 10579312
- Publisher / Repository:
- Cambridge University Press
- Date Published:
- Journal Name:
- Journal of Glaciology
- Volume:
- 70
- ISSN:
- 0022-1430
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1017/jog.2024.41
