7 September 2020
The Koidern landslide: a long runout event in Canada
Posted by Dave Petley
The Koidern landslide: a long runout event in Canada
Apologies for the lack of posts of late – due to Covid-19, and its associated secondary hazards, my day job is taking all of my time at the moment. Anyway, on Saturday Brent Ward tweeted a fantastic set of aerial images of the Koidern landslide, in the Yukon of Canada. This is one of the most spectacular landslides of the year to date:-
Finally some pictures of the Koidern Landslide. Start with some aerial pictures and then some more details. Some really interesting mollards, and some have remobilized! It is a long thread as it was a really cool landslide! 1/10 pic.twitter.com/fUwsPt41B4
— Brent Ward 🇺🇦 (@GeoBrentatlarge) September 4, 2020
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Brent has posted a thread of images of the Koidern landslide, which includes this pair of tweets showing the structure of the landslide (mollards are cones of rock avalanche material) and the landslide dam:-
The landslide has formed a lake, and the nick point is slowly migrating upstream. 8/10 pic.twitter.com/QnPFAd2syB
— Brent Ward 🇺🇦 (@GeoBrentatlarge) September 4, 2020
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The Koidern landslide is a very interesting rock avalanche, showing quite high mobility. Note the very clear main track of the landslide, as well as the areas on either with lower levels of debris. It appears to me that a part of the landslide has super-elevated on the outside of the first bend. Some landslide debris has also spilled out on the true right side of the track.
The images show that the landslide dam has overtopped; given its size and the remote location the hazard is very low.
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Quickslide 1: A spectacular rockfall at Cima Canali at Pale di San Martino in the Dolomites
This is a pretty cool video of a recent rockfall. Note the very large boulder that leaves the dust cloud on the right hand side and disappears down the valley:-
Friday at Cima Canali at Pale di San Martino (Dolomites). Not so high up as the Drus and judging by the debris cone below not the only #rockfall ever at this spot. But quite sizable and in sync with the increasing seasonal warming of high #mountain rock walls. pic.twitter.com/RvAxF63E2V
— Jan Beutel (@jan_beutel) September 6, 2020
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Quickslide 2: Landslides from Typhoon Haishen in Japan
Typhoon Haishen swept across Japan over the weekend. At least one substantial landslide has been reported. The Mainichi reports:
The typhoon is now headed north towards South and North Korea.
Dave Petley is the Vice-Chancellor of the University of Hull in the United Kingdom. His blog provides commentary and analysis of landslide events occurring worldwide, including the landslides themselves, latest research, and conferences and meetings.
Hi Dave,
Thanks for the interest in the Koidern landslide! It certainly is interesting and we hope to go back there next year. I was remiss in not mentioning in the Twitter thread that my colleague (and the one paying for the helicopter!) was Kristy Kennedy, Yukon Geological Survey. She was the one that heard through an outfitter and Parks Canada about the landslide, so we detoured there that day. Also, through feedback from twitter and because we got back from the field to better internet, we have managed to narrow down the timing to sometime between Jan 21-31, so the deciduous leaves were lying. This timing does help to explain the more fluid remobilisation along the tributary valley due to snow. We hope to refine the timing through seismic records. There are also two other smaller landslides within a few km that look to be of a similar age. I think a January landslide is a little unusual, I assumed that it would have occurred in the spring, associated with snowmelt. Maybe there was an unusual warm spell then? Or possibly a small earthquake on the Denali Fault? We will be investigating further.
At 0:41 —- at lower right half way down—-do i see two people???? a few seconds later, when the camera swings back to the same area, the two tiny images are gone. (probably boulders or something?)
It is worth recalling Brent that the famous Hope Slide occurred on snow. It was the 9th January 1965. I do recall the event, because it was the day I emigrated to Canada !
Have you seen this landslide/rockfall Dave?
https://www.instagram.com/p/CFLYL-Agp9H/