← Back to Sessions

Distributed Acoustic Sensing Reveals What’s in Store (Glacier)

Description: 

The Greenland ice sheet is the largest contributor to present global mean sea level rise, and dynamics of Greenland glaciers therefore exert a primary influence on the extent of present and future sea level rise. Frictional, deformational, and hydrological processes near the ice sheet bed control the dynamics of many glaciers, yet our understanding of glacier dynamics relies predominantly on surface measurements, and observing glacier processes at depth remains a challenge. While borehole seismic deployments provide continuous recordings of elastic waves near the glacier bed at a high temporal resolution, the spatial extent of such deployments is often limited to a single point. Novel fiber optical techniques like distributed acoustic sensing (DAS) retain the high temporal resolution of traditional borehole seismic deployments while providing excellent spatial resolution throughout the entire thickness of the glacier. Here, we explore three days of continuous DAS data recorded between July 6 and July 9, 2019 at Store Glacier in West Greenland. To image the velocity structure of the ice, we compute ambient noise cross-correlations for the entire dataset. Correlation functions stacked over a duration of one hour reveal P-waves and S-waves that propagate from the near-surface at average velocities consistent with the results of an active source survey carried out using the same fiber deployment (Booth et al, 2020). We perform ambient noise cross correlation using data recorded by each channel to characterize spatiotemporal variation in glacier strain. Our results suggest that the broad region within a few kilometers of the borehole experiences diurnal periodicity in glacier strain with minimal depth variation, consistent with behavior predicted by a classic simplified model of glacier flow over a deformable bed (MacAyeal, 1989). However, our results also suggest that the region immediately local to the borehole experiences a more complicated strain regime that may be explained by bumpy bedrock topography or complex basal hydrology.

Session: Applications and Discoveries in Cryoseismology Across Spatial and Temporal Scales [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Stephanie

Student Presenter: No

Invited Presentation: 

Authors