Active and passive seismic surveys over the grounding zone of Eastwind Glacier, Antarctica

Glacier grounding zones, where ice transitions from resting on land to floating on ocean, are critical to understanding ice sheet dynamics and stability. Despite their importance, these regions are challenging to study directly due to their inaccessibility and the inherent risks of fieldwork. To address this, we conducted seismic investigations at Eastwind Glacier, Antarctica, an accessible grounding zone near McMurdo Station and Scott Base, as part of the EGGS on TOAST project. Our fieldwork included deploying 330 three-component seismic nodes across the grounding zone during the austral summer of 2022/23, capturing continuous data for nine days on all nodes, with extended recordings of 19 days on 150 nodes. Active-source seismic data were acquired using hammer-and-plate shots, both densely spaced along the array's centerline and at individual node locations. In the following field season (2023/24), we supplemented these observations with distributed acoustic sensing (DAS) using a fiber optic cable positioned downstream of the grounding line for cross- and along-flow imaging. Initial analyses of the seismic data reveal key features, such as the flotation point of ice and ice and firn thickness variations. Additionally, passive seismic methods provide insights into icequake activity and ambient noise characteristics. This comprehensive dataset offers a new perspective on grounding zone processes and serves as a valuable resource for testing innovative cryo-seismological techniques.