B.C. landslide triggered 100-metre tall lake tsunami, study shows [View all]

A massive landslide on B.C.'s remote central coast in 2020 triggered a lake tsunami over 100 metres tall, according to a new paper published by researchers from the University of Northern British Columbia.

Described as a rare "hazard cascade," the tsunami then sent a vast torrent of water or "outburst flood" into Elliot Creek, uprooting trees, soil and rock as it surged down the valley. The slurry was in turn propelled in the Southgate River and then Bute Inlet, leaving a devastated landscape in its wake.

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"The landslide displaced enough water to cause a tsunami with a wave height that exceeded 100 metres. This drained most of the lake water which then travelled down a 10-kilometre-long channel causing widespread channel erosion and loss of salmon habitat."

Rapid thinning and retreat of the glacier at the slide site set the stage for the hazard cascade, according to the study co-author.

"Once you lose the supporting structure of the ice that is backstopping and protecting these steep slopes, they are much more susceptible to failure," said UNBC geography professor Brian Menounos.

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https://www.cbc.ca/news/canada/british-columbia/b-c-landslide-triggered-100-metre-tall-lake-tsunami-study-shows-1.6401469