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Lookup NU author(s): Professor Stuart DunningORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Rockfalls are an efficient agent of landscape denudation and a crucial but poorly quantified component of the glacier debris supply cascade. Climate change is driving increased rockfall generation as rising air temperatures cause glacier thinning and thawing of permafrost. These processes alter rock slope stress profiles and thermal regimes, leading to greater sediment fluxes in cryospheric systems as landscapes adjust to ice-free conditions. We used repeat terrestrial laser scans combined with change detection during the summer of 2019 to quantify rockfall activity over a 0.7 km2 rock wall area along the ablation zone lateral margins of the debris-covered Miage Glacier, Italy. We detected 2,581 rockfalls spanning eight orders of magnitude (10−3–104 m3; median 0.021 m3) including an event of about 28 × 103 m3 from a newly deglaciated slope. Large rockfalls (≥10 m3) on lower, glacier-proximal slopes, whilst infrequent (<1% by count), achieved the most geomorphic work. Most (79%) rockfalls originated within <75 m above the glacier surface (mAG; representing 29% of the survey area); a boundary that corresponds with the Little Ice Age trimline. Some rockwalls exhibited a secondary zone of higher rockfall activity at about 125–150 mAG, revealing a second trimline with a millennial-scale signal of elevated rock damage possibly associated with ice surface dynamics during or immediately after the Younger Dryas Stadial. Modelled rockfall runout distances were determined in part by path topography: rockfalls originating from lower slopes travelled <100 m horizontally whilst those originating higher could travel up to 650 m, approaching the glacier centreline, reflecting a spatial differential in hillslope-glacier connectivity that will evolve concurrently with cryospheric degradation in the wider catchment. We show that detailed, short-term monitoring campaigns can yield novel and useful descriptions of mass movement fluxes and spatial patterns in alpine regions. Expanding our dataset by observing rock walls near the equilibrium line altitude could help bridge the longitudinal gap to existing high elevation inventories to provide a more unified picture of rockfall dynamics in deglaciating catchments.
Author(s): Stewart R, Westoby M, Dunning S, Rowan AV, Woodward J
Publication type: Article
Publication status: Published
Journal: Earth Surface Processes and Landforms
Year: 2025
Volume: 50
Issue: 15
Online publication date: 21/12/2025
Acceptance date: 24/11/2025
Date deposited: 06/02/2026
ISSN (print): 0197-9337
ISSN (electronic): 1096-9837
Publisher: John Wiley & Sons Ltd.
URL: https://doi.org/10.1002/esp.70217
DOI: 10.1002/esp.70217
Data Access Statement: The full rockfall inventory that is reported in this paper, and theMATLAB code which was used to derive rockfall volumes via 3Dchange detection and hull-fitting, are archived at https://zenodo.org/record/6701335#.ZCbtdnbMKUk. Aerial LiDAR data for rockfall run-out modelling are attributed to the Natural Environment ResearchCouncil (NERC) Airborne Research and Survey Facility (projectsGB07–09 and GB07–10)
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