Overview:
A large landslide that was triggered by heavy rainfall has killed three people and left three more missing.
The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
At about 9 pm local time on 20 November 2023, a large landslide occurred near to Wrangell in Alaska, USA. At the time of writing, three people have been confirmed to have been killed (including a child), whilst a further three are reported to be missing. Rescue operations are ongoing.
The Alaska Department of Transportation and Public Facilities has released this image of the landslide:-
Meanwhile, Eric Stone tweeted this image of the landslide, captured by Sunrise Aviation:-
An article on ABC News also has an image of the full track of the landslide – it is worth a look.
The landslide appears to have occurred in dense forest, with the failure initiating high on the slope. The trigger was a period of heavy rainfall. It seems to have started as a comparatively shallow slide in regolith, but then to have incorporated debris and a lot of timber as it travelled downslope. It is likely that it would have been a flow on the lower slopes.
In many ways the landslide is reminiscent of the 2 December 2020 Beach Road landslide, also in Alaska. There are also some similarities to the 12 July 2012 Johnsons Landing landslide in Canada.
This story will develop through the next few days, but once again the event reinforces the impact of extreme rainfall events on slopes.
Many thanks to the various people who highlighted this one to me – your help is much appreciated.