05 May 2023
 | 05 May 2023

Alpine hillslope failure in the western US: Insights from the Chaos Canyon landslide, Rocky Mountain National Park USA

Matthew C. Morriss, Benjamin Lehmann, Benjamin Campforts, George Brencher, Brianna Rick, Leif Anderson, Alexander L. Handwerger, Irina Overeem, and Jeffrey Moore

Abstract. The Chaos Canyon landslide, which collapsed on the afternoon of June 28th, 2022 in Rocky Mountain National Park presents an opportunity to evaluate instabilities within alpine regions faced with a warming and dynamic climate. Video documentation of the landslide was captured by several eyewitnesses and motivated a rapid field campaign. Initial estimates put the failure area at 66,630 m2, with an average elevation of 3,555 m above sea level. We undertook an investigation of previous movement of this landslide, measured the volume of material involved, evaluated the potential presence of interstitial ice/snow within the failed deposit, and examined potential climatological forcings at work in causing the collapse of the slope. Satellite radar and optical measurements were used to measure deformation of the landslide in the years leading up to collapse. From 2017 to 2019, the landslide moved ∼5 m yr-1, accelerating to 17 m yr-1 in 2019. Movement took place through both internal deformation and basal sliding. Climate analysis reveals the collapse took place during peak snowmelt, and 2022 followed 10 years of higher than average positive degree day sums. We also made use of slope stability modeling to test what factors controlled the stability of the area. Models indicate even a small increase in the water table reduces the Factor of Safety to <1, leading to failure. Material volumes were estimated using Structure from Motion (SfM) models incorporating photographs from two field expeditions on July 8th, 2022 – 10 days after the slide. Detailed mapping and SfM models indicate ∼ 1,258,000 ± 150,000 m3 of material was deposited at the slide toe and ∼1,340,000 ± 133,000 m3 of material was evacuated from the source area. Our holistic approach to the collapse of the Chaos Canyon landslide provided an opportunity to examine a landslide that may be representative of future dynamic alpine topography, wherein failures becomes more common in a warming climate.

Matthew C. Morriss et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-697', Anonymous Referee #1, 19 Jun 2023
    • AC1: 'Reply on RC1', Matthew Morriss, 15 Jul 2023
  • RC2: 'Comment on egusphere-2023-697', Sean Lahusen, 30 Jun 2023
    • AC2: 'Reply on RC2', Matthew Morriss, 20 Aug 2023
  • RC3: 'Comment on egusphere-2023-697', Alex Tye, 07 Aug 2023
    • AC3: 'Reply on RC3', Matthew Morriss, 29 Aug 2023

Matthew C. Morriss et al.

Matthew C. Morriss et al.


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Short summary
In this manuscript, we investigated the June 28th, 2022 collapse of the Chaos Canyon landslide in Rocky Mountain National Park, Colorado, USA. We found the landslide was moving prior to its collapse, took place at peak spring snowmelt, and temperature modeling indicates the potential presence of permafrost, indicating this collapse could be due to permafrost thaw. We hypothesize this landslide could be part of the broader landscape evolution changes to alpine terrain caused by a warming climate.