Geographic-information-system-based topographic reconstruction and geomechanical modelling of the Köfels rockslide

Zangerl, Christian; Schneeberger, Annemarie; Steiner, Georg; Mergili, Martin

doi:https://doi.org/10.5194/nhess-21-2461-2021

Articles | Volume 21, issue 8

https://doi.org/10.5194/nhess-21-2461-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/nhess-21-2461-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 21, issue 8

Research article

|

23 Aug 2021

Research article |

| 23 Aug 2021

Geographic-information-system-based topographic reconstruction and geomechanical modelling of the Köfels rockslide

Christian Zangerl, Annemarie Schneeberger, Georg Steiner, and Martin Mergili

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Final revised paper (published on 23 Aug 2021)
Preprint (discussion started on 09 Sep 2020)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

SC1: 'Comment', Azealdeen Al-Jawadi, 15 Sep 2020
- AC1: 'Answer', Christian Zangerl, 14 Dec 2020
RC1: 'Referee comments', Gregor Ortner, 09 Oct 2020
- AC2: 'Comments on Reviewer 1', Christian Zangerl, 14 Dec 2020
RC2: 'Triggering Mechanisms of Large Rock Slope Failures', Anonymous Referee #2, 22 Oct 2020
- AC3: 'Comments on Reviewer 2 - Anonymous (Referee RC2)', Christian Zangerl, 14 Dec 2020
RC3: 'Review', Anonymous Referee #3, 04 Nov 2020
- AC4: 'Comments on Reviewer 3 - Anonymous (Referee RC3)', Christian Zangerl, 14 Dec 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (further review by editor and referees) (14 Dec 2020) by Yves Bühler

AR by Christian Zangerl on behalf of the Authors (17 May 2021) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (18 May 2021) by Yves Bühler

RR by Anonymous Referee #3 (23 Jun 2021)

Suggestions for revision or reasons for rejection

I enjoyed reading the second revision of the paper. I found the article to be well written and informative. I especially liked the idea that modern remote sensing techniques (and DEM) can be used to "revisit" the major rockslides. Indeed, much progress has been made in thiese areas.

Some minor points:

Line 160 Instead of 1.6(10^16) J, maybe write 1.6(10^7) GJ. Maybe GJ is a better unit.

Line 280 I read the recent Science article concerning the Chamoli rock/ice avalanche. There the authors reported the volume to be about 27 mio m3. The Piz Cengalo slide was approx 2 mio m3. Here the volumes are reported in km3 = 10^9 m3. Therefore the volume is 3100 mio m3? This is immense. Perhaps the authors should write 3.1 km3 = 3100 mio m3 to give the reader an impression of the volume.

Discusision of the DEM method. There are problems with the DEM method. For example, all the stresses are based on an accurate calculation of the elastic strain. As long as the material remains "in place" and deformations are small this is not a problem. However, when deformations become large, the calculated state of strain/stress are approximations at best.

The qualities of the figures is excellent. Very clear.

I wonder about the conclusions. The last line of the paper is insightful: "Thus, a particular geological disposition ... responsible for the ... slide" That is, we were unable to model the slide with resonable parameters, therefore we must search for other triggers --seismic, progressive strength degradation ... etc. Couldn't there be another conclusion. There is something wrong with the model? Something is missing. If other researchers will confront this problem again (they certainly will), what modelling advice would you provide? Or, are the boundary conditions/material parameters too unknown to improve the modelling?

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ED: Publish subject to technical corrections (24 Jun 2021) by Yves Bühler

AR by Christian Zangerl on behalf of the Authors (06 Jul 2021) Author's response Manuscript

Post-review adjustments

AA: Author's adjustment | EA: Editor approval

AA by Christian Zangerl on behalf of the Authors (17 Aug 2021) Author's adjustment Manuscript

EA: Adjustments approved (17 Aug 2021) by Yves Bühler

Short summary

The Köfels rockslide in the Ötztal Valley (Austria) represents the largest known extremely rapid rockslide in metamorphic rock masses in the Alps and was formed in the early Holocene. Although many hypotheses for the conditioning and triggering factors were discussed in the past, until now no scientifically accepted explanatory model has been found. This study provides new data and numerical modelling results to better understand the cause and triggering factors of this gigantic natural event.