The Many Mysteries of the 2022 Chaos Canyon landslide in Rocky Mountain National Park

On 28 June 2022, ~2 million m3 of ice-rich debris mobilized from the southeast flank of Hallett Peak in Rocky Mountain National Park. The material slid rapidly for about 245 m into Chaos Canyon, a popular bouldering destination, stopping as it reached a relict rock glacier composed of massive boulders that fills the valley floor. Several climbers were bouldering near the toe of the landslide when it occurred. The group narrowly escaped and caught parts of the event on video, resulting in substantial nationwide media coverage. 

In this talk, I will detail a multifacted investigation in which we used eyewitness accounts, field and remote sensing techniques, historic climate data, and seismic recordings to unravel the mysteries of this unusual landslide and the events leading up to it. 

Direct observations of melting blocks of icy debris in the landslide deposits coupled with decades of slope deformation patterns correlated with warming temperatures strongly suggest permafrost degradation was the likely culprit. The main failure sequence itself was also relatively complex, with deformation starting earlier in the day and culminating in 3 energetic episodes of sliding. The slower deformation of the first energetic episode transitioned suddenly into the main and most energetic sliding episode immediately following a distant (~36 km) M1.4-equivalent reservoir construction blast. This raises interesting questions of whether the blast was a “red herring” or whether the very minor levels of shaking could have influenced the behavior of a marginally unstable landslide already in motion.