The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
Between 6 and 8 June 2024, a landslide destroyed a section of State Highway 22 along the Teton Pass in Wyoming. No lives were lost in this major landslide, although a motorcyclist may have been injured in a crash associated with road damage, and the road has now been completely destroyed.
The Wyoming Department of Transport has been admirably transparent about this landslide, with an excellent set of resources and images, and a timeline of the sequence of events, on a dedicated webpage.
The landslide is spectacular – the tweet below includes a video that superimposes before and after the failure:-
The drama started the previous day when large cracks started to form across the road. New Civil Engineer has an account of the events of the site as maintenance crews attempted to patch the road. However, over the course of two days the slope failed completely, leaving a large section of the road destroyed.
The Associated Press footage in the tweet below shows the failure in more detail:
The location of the landslide on Teton Pass is [43.50365, -100.97556]. The Google Earth view below shows the site – I have selected an image from 2013 as it provides the best clarity:-
The site appears to be a large fill embankment built on natural terrain. The footage suggests that the landslide is a large-scale slump, with the lower portions of the landslide forming a more mobile flow (which is normal in this situation). Note the displaced sections of road in this Wyoming Department of Transport image of the site:-
The images before the failure are quite intriguing. This is a screenshot from the before failure drone footage from Wyoming Department of Transport:-
Does this footage suggest a smaller failure was forming in the embankment at this time, directly below the structures in the middle of the image? I am unsure.
It will be interesting to understand the causes of this landslide, which could be failure of the natural terrain below the embankment or perhaps a drainage issue in the embankment itself, which then failed in a progressive manner. At first glance the latter seems more likely.
Reconstruction of the road will be a major project given the need to find a strong foundation for the reconstructed section of highway. In the meantime, a detour is being constructed through the inside of the bend that should allow the road to reopen quite quickly.
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