The Glacier Shakes at Sunset: New Ice-Quake Data Illuminating Glacier-Bed Mechanics

Author: Nate (Nathan) T. Stevens (PhD expected 2022)

Over the summer, UW-Madison Geo-Badgers Collin Roland, Dougal Hansen, Prof. Luke Zoet, and myself, along with our PSICE collaborator Emily Schwans, set out to “take the pulse” of Saskatchewan Glacier, located in Canada’s Banff National Park, using seismometers, GPS sensors, hydrologic pressure transducers, and a portable weather station.

Through this, we hoped to settle a disagreement between classic glacier sliding theory1 and recent laboratory results from L. Zoet & N. Iverson2 on how glaciers slide over stair-shaped bedrock. Settling such matters is critical to better forecasting rates of sea-level rise in a warming world3,4.

We lived at the toe of Saskatchewan Glacier for 29 days, re-installing some 40 seismometers every 2-3 days – a work of no small effort.

 

We kept GPS units running using traveler’s power-banks – even rationing electricity during a cloudy week to keep these and safety equipment charged…

all while living in very close quarters, despite the large valley – all with only 1 shower per week during resupply runs, which requiring a 11 mile round-trip hike and 4 hours of driving.

Several months (and MANY showers) later, we have worked to analyze a veritable mountain of data. While our results are still in their infancy, we have been able to recover a great many things:

1) We observed an increase in the amount of ice-quakes located at the glacier’s bed during evening hours as melt-water flow through the glacier wains. Some of these seismic “bursts” are accompanied by acceleration of the glacier, pointing towards the findings of L. Zoet & N. Iverson2⁠ in this setting.

2) Using the background “quivering” of the earthquake, we have made the most detailed estimates of Saskatchewan Glacier’s thickness since the last experiment to do so from over 75 years ago5!

3) Our new map of the glacier’s bed topography, coupled with observed centers of seismic activity have fascinating implications that are the focus of our ongoing research.

These (and more) results will be presented at the upcoming Student Seismology Workshop at Columbia University/ Lamont-Doherty Earth Observatory in New York in March, the European Geosciences Union General Assembly in Vienna, Austria this May, and are in preparation to submit for peer-review in the coming months.

  1. Iken, A. The Effect of the Subglacial Water Pressure on the Sliding of a Glacier in an Idealized Numerical Model. J. Glaciol. 27, (1981).
  2. Zoet, L. K. & Iverson, N. R. Rate-weakening drag during glacier sliding. J. Geophys. Res. Earth Surf. 121, 1328–1350 (2016).
  3. Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. in (Eds. Stocker, T. F. et al.) (Cambridge University Press, 2013).
  4. Scambos, T. A. et al. How much, how fast?: A science review and outlook for research on the instability of Antarctica’s Thwaites Glacier in the 21st century. Glob. Planet. Change 153, 16–34 (2017).
  5. Meier, M. F., Rigsby, G. P. & Sharp, R. P. Preliminary data from Saskatchewan Glacier, Alberta, canada1. Arctic (1954)

    All photos, video, and written content are the product of Nathan T. Stevens (C) 2019, 2020. All Rights Reserved.