The 1 September 2022 rock avalanche on the Ecstall River in British Columbia, Canada

On 1 September 2022 a large rock avalanche occurred on the Ecstall River in British Columbia, Canada.  This event was identified by Göran Ekström at Columbia University from seismic data, and has then been tracked down and documented by a multidisciplinary team that includes Brian Menounos and Marten Geertsem from UNBC, and scientists from the BC Government and the Hakai Institute.  The event is well described in a series of tweets by Brian Menounos (@brianmenounos):-

On 1 Sept, @lamontdoherty Göran Ekström detected a seismic event north of Kitimat which turned out to be an ice/rock avalanche on the Ecstall River that slammed into a lake and created a downstream flood similar to the event at Elliot Creek. pic.twitter.com/7mf54wilqY

— Brian (@brianmenounos) September 18, 2022

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It is worth looking at the full set of tweets to get an understanding of this event and of the work of the team.

On first inspection the landslide appears to have started as a failure on a near-vertical rockface, and then to have transitioned into a classic ice/rock avalanche.  The source of the landslide is at about 53.965, 129.323.  This is a Planet Labs image of the site before the landslide:-

Satellite image of the site of the rock avalanche on the Ecstall River in BC, collected on 1 August 2022. Image copyright Planet Labs, used with permission.

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And this is the site afterwards:-

Satellite image of the rock avalanche on the Ecstall River in BC, collected on 20 September 2022. Image copyright Planet Labs, used with permission.

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This is a very large landslide with a long runout.  I have tried to set up a juxtapose below to allow you to compare the two images:-

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Am additional point of interest here is the image of 1 September 2022, the day of the landslide.  The image itself is clear, except in the valley affected by the landslide.  Is this the remains of the dust cloud?

Satellite image of the rock avalanche on the Ecstall River in BC, collected on 1 September 2022. Image copyright Planet Labs, used with permission.

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Whilst this landslide is in a remote location, it is causing concern about the potential impact on salmon spawning grounds.  Global News has an article providing some detail.

The team involved in the research into this landslide are world leading, so no doubt we will see a full description and analysis of it in due course. It is a fascinating event.

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Acknowledgements

The project team outlined above have rapidly undertaken an analysis of this event and have posted the data online.  Thanks to them for doing so.  The images are from the wonderful people at Planet Labs.

Planet Team (2022). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/