Quantifying subsurface fracture damage in glaciers using fiber-optic seismology

Area of Science:

• Glaciology
• Seismology
• Geophysics

Background:

• Crevasses critically influence glacier and ice shelf stability.
• Deep crevasse penetration can lead to calving, ice avalanches, and catastrophic ice shelf collapse.
• Quantifying subsurface fracture damage in glaciers is challenging and largely unaddressed.

Purpose of the Study:

• To demonstrate the efficacy of distributed acoustic sensing (DAS) for quantifying subsurface fracture damage in alpine glaciers.
• To establish seismic anisotropy as a method for estimating fracture extent.
• To investigate crevasse icequake failure mechanisms and their contribution to ice volume loss.

Main Methods:

• Deployment of distributed acoustic sensing (DAS) technology at an alpine glacier.
• Analysis of seismic anisotropy to quantify the extent of subsurface fractures.
• Characterization of crevasse icequake failure mechanisms, focusing on tensile opening.

Main Results:

• DAS technology provides unprecedented detail in quantifying subsurface fracture damage.
• Seismic anisotropy effectively quantifies fracture extent within the glacier.
• Icequake-derived crevasse opening (approximately 8% of ice volume) is consistent with anisotropy estimates, indicating fracture-dominated damage.

Conclusions:

• Distributed acoustic sensing offers a scalable approach to monitor subsurface ice damage.
• This method complements existing satellite surface observations for a comprehensive understanding of glacier health.
• Findings have implications for monitoring hazardous alpine glaciers and assessing fracture extent in ice sheets and ice shelves.