Preprints
https://doi.org/10.5194/egusphere-2024-3074
https://doi.org/10.5194/egusphere-2024-3074
25 Oct 2024
 | 25 Oct 2024

4D imaging of a near-terminus glacier collapse feature through high-density GPR acquisitions

Bastien Ruols, Johanna Klahold, Daniel Farinotti, and James Irving

Abstract. Recent advancements in drone technology have introduced new possibilities for high-density 3D and 4D ground-penetrating radar (GPR) data acquisition over alpine glaciers. In this study, we present a 4D dataset acquired over a near-terminus collapse feature at the Rhône Glacier in Switzerland. The survey covers an area of approximately 100 m x 150 m, consists of over 100 parallel GPR lines with a lateral spacing of 1 m, and was repeated four times between July and October 2022. The glacier’s rough surface made such high-resolution and high-density surveying impossible with conventional acquisition methods, highlighting the advantages of the drone-based GPR system. The GPR data provide insights into the formation of the collapse feature as well as the evolution of associated glaciological structures. Our analysis suggests that the collapse initiated where the main subglacial water channel meanders and merges with a smaller secondary channel, coinciding with a small step in bedrock topography. After initiation, the subglacial cavity expanded through a combination of ice melting and mechanical failure, with ice lamellas detaching from the cavity roof. This process led to a progressive thinning of the roof, contributing to further instability. At the surface, these subsurface processes manifested as concentric circular crevasses, ultimately culminating in the collapse of the cavity roof. The GPR measurements also reveal the rapid temporal evolution of the main subglacial channel downstream of the cavity. During the observed summer, the channel underwent significant changes in both shape and size, which we attribute to the advection of warm air from the glacier’s large portal and the resulting increase in melt at the channel walls.

Competing interests: At least one of the (co-)authors is a member of the editorial board of The Cryosphere. The peer-review process was guided by an independent editor, and of the authors also have no other competing interests to declare.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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Journal article(s) based on this preprint

26 Sep 2025
| Highlight paper
4D GPR imaging of a near-terminus glacier collapse feature
Bastien Ruols, Johanna Klahold, Daniel Farinotti, and James Irving
The Cryosphere, 19, 4045–4059, https://doi.org/10.5194/tc-19-4045-2025,https://doi.org/10.5194/tc-19-4045-2025, 2025
Short summary Co-editor-in-chief
Bastien Ruols, Johanna Klahold, Daniel Farinotti, and James Irving

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3074', Anonymous Referee #1, 01 Dec 2024
    • AC1: 'Reply on RC1', Bastien Ruols, 29 Apr 2025
  • RC2: 'Comment on egusphere-2024-3074', Anonymous Referee #2, 27 Feb 2025
    • AC2: 'Reply on RC2', Bastien Ruols, 29 Apr 2025

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-3074', Anonymous Referee #1, 01 Dec 2024
    • AC1: 'Reply on RC1', Bastien Ruols, 29 Apr 2025
  • RC2: 'Comment on egusphere-2024-3074', Anonymous Referee #2, 27 Feb 2025
    • AC2: 'Reply on RC2', Bastien Ruols, 29 Apr 2025

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Publish subject to revisions (further review by editor and referees) (29 Apr 2025) by Kristin Poinar
AR by Bastien Ruols on behalf of the Authors (29 Apr 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish subject to minor revisions (review by editor) (22 May 2025) by Kristin Poinar
AR by Bastien Ruols on behalf of the Authors (28 May 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (30 May 2025) by Kristin Poinar
AR by Bastien Ruols on behalf of the Authors (12 Jun 2025)  Manuscript 

Journal article(s) based on this preprint

26 Sep 2025
| Highlight paper
4D GPR imaging of a near-terminus glacier collapse feature
Bastien Ruols, Johanna Klahold, Daniel Farinotti, and James Irving
The Cryosphere, 19, 4045–4059, https://doi.org/10.5194/tc-19-4045-2025,https://doi.org/10.5194/tc-19-4045-2025, 2025
Short summary Co-editor-in-chief
Bastien Ruols, Johanna Klahold, Daniel Farinotti, and James Irving
Bastien Ruols, Johanna Klahold, Daniel Farinotti, and James Irving

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Short summary
We demonstrate the use of a drone-based ground-penetrating radar (GPR) system to gather high-resolution, high-density 4D data over a near-terminus glacier collapse feature. We monitor the growth of an air cavity and the evolution of the subglacial drainage system, providing new insights into the dynamics of collapse events. This work highlights potential future applications of drone-based GPR for monitoring glaciers, in particular in regions which are inaccessible with surface-based methods.
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