Icequake insights on transient glacier slip mechanics near channelized subglacial drainage

Nathan T. Stevens, Lucas K. Zoet, Dougal D. Hansen, Richard B. Alley, Collin J. Roland, Emily Schwans, Cameron S. Shepherd

Research output: Contribution to journalArticlepeer-review

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Glacier slip modulates sea-level rise. Most slip models assume quasi-equilibrium process dynamics and debris-free basal ice, but observations regularly show debris-rich basal ice sliding under transient external forcings, placing theory and observation in tension. Seismicity generated by slip (icequake activity) provides a window into subglacial dynamics, but basal icequakes are often too sparse to resolve diagnostic trends at scales relevant to reveal slip-facilitating processes. We present a rich icequake catalog from an alpine glacier with sub-diurnal and decametric resolution that overcomes these limitations. We find characteristic trends between subglacial hydrology, slip, and seismicity that corroborate emerging models of transient slip over hard beds and highlight the importance of basal debris in slip dynamics. Specifically, icequakes are more abundant when subglacial cavities are likely large—a configuration that favors reduced drag in debris-free models—but this occurs as slip decelerates. Drag between entrained debris and the bed is enhanced under the same conditions and favors seismogenesis, which reconciles this discrepancy and may indicate slip-stabilizing feedback not considered in most models of glacier motion. Furthermore, we characterize spatial, temporal, and magnitude scaling patterns in this seismic catalog consistent with trends observed in previous glacier seismicity studies, suggesting that the slip-facilitating process dynamics characterized at Saskatchewan Glacier are relevant in other parts of the cryosphere.

Original languageEnglish (US)
Article number118513
JournalEarth and Planetary Science Letters
StatePublished - Feb 1 2024

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Space and Planetary Science
  • Earth and Planetary Sciences (miscellaneous)

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