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Plucking Base Notes: Seismic Character of a Potential Glacial Quarrying Event at Saskatchewan Glacier, Canadian Rocky Mountains

Description: 

Glaciers are one of the most powerful geomorphic forces on Earth, carving landscapes through a combination of abrasion and quarrying. These rock fracturing processes produce seismic emissions, as observed in experimental conditions and predicted in numerical theory. Glacier seismicity also arises from profoundly diverse sources, which hinders our ability to substantiate causal relationships between field observations and glacier bed processes. Recent bed-proximal seismic observation of a subglacial asperity provided unparalleled insights on the seismic character of abrasion that supports numerical and experimental theory (Gräff et al., 2021). Similar empirical support has not been reported for quarrying.

Abundant and accurately locatable glacier-bed seismicity observed with a dense surface array at Saskatchewan Glacier in August 2019 provided new empirical support for hydrologically modulated transient slip mechanics (Stevens et al., accepted). This catalog also contains a burst of hundreds of bed-proximal events clustered on the headwall of an overdeepening as glacier slip accelerated on the morning of August 10th; a normally aseismic time within the diurnal seismic cycles observed during this month. The timing, position, and dynamic context of this seismic cluster is consistent with characteristics of subglacial quarrying experiments and relevant numerical theory (Cohen et al., 2006). Here we present detailed analysis of this potential quarrying event, refining the event catalog through manual reanalysis, double-difference relocation, and source parameter estimation to further motivate causal linkages to glacier quarrying theory.

Cohen, D. and 4 others, 2006, Role of transient water pressure in quarrying: A subglacial experiment using acoustic emissions. JGR-ES. doi: 10.1029/2006JF000439.

Gräff, D. and 5 others, 2021, Fine structure of microseismic glacial stick-slip. GRL. doi: 10.1029/2021GL096043.

Stevens, N.T., and 6 others, Accepted, Icequake insights on transient glacier slip mechanics near channelized subglacial drainage. EPSL. doi: 10/1016/j.epsl.2023.118513

Session: Applications and Discoveries in Cryoseismology Across Spatial and Temporal Scales - I

Type: Oral

Date: 5/2/2024

Presentation Time: 05:00 PM (local time)

Presenting Author: Nathan

Student Presenter: No

Invited Presentation: 

Authors