Landscape-Altering Climate Change

"[The landslide was not the largest ever in Canada, but it was] very, very enormous."

"Imagine a landslide with a mass equal to all of the automobiles in Canada travelling with a velocity of about 140 kilometres an hour when it runs into a large lake."  

"This drained most of the lake water, which then travelled down [a 10-km]-long channel causing widespread channel erosion and loss of salmon habitat,"

"It took about 30 seconds from when the rock started to detach on the slope for that mass of rock to enter the lake and, that produced a huge displacement wave. And everything was removed, all the trees and the soil, and so that was pretty spectacular." 

Marten Geertsema, adjunct professor, University of Northern British Columbia

 

"What we don't know is whether the final straw that broke the camel's back, for lack of a better phrase, was a rainstorm or unusually wet conditions during 2020."

"The ability to have perhaps half of the lake volume drained within ten minutes or less, I mean, it was tremendously powerful and disruptive."

"It feels very small [as a human], studying things with such power."

Professor Brian Menounos, Canada Research Chair in glacier change, University of Northern British Columbia

Brian Menounos, a professor of geography at the University of Northern British Columbia, surveys a debris field caused by a landslide and outburst flood off the coast of B.C. (Briar Stewart/CBC News)

A massive landslide presumed to have been caused by a retreating glacier located in a remote valley in British Columbia, caused a 100-metre-tall tsunami to occur, wiping out kilometres of salmon habitat. The earth tremors caused by the landslide was powerful enough to be detected by sensitive scientific equipment located as distant as Australia, according to a study published in Geophysical Research Letters.

 

An immense load of 18 million cubic metres of rock was sent cascading down a mountainside on November 28, 2020, as a result of the landslide uprooting trees and displacing soil, on its way to slamming into Elliot Creek. In Germany, Japan and Australia, earthquake sensors detected the landslide, the study points out, emphasizing its powerful effect. 

Salmon spawning habitat was destroyed over 8.5 kilometres of the creek runway, sending a plume of mud and organic matter over 60 kilometres into Bute Inlet located around 150 kilometres from Vancouver. At Columbia University in New York, a professor simultaneously measured a magnitude-5 earthquake in the area.

Dr.Geertsema described most of the lake water being drained and forced down a 10-kilometre-long channel when the massive slide fell, causing widespread erosion and loss of salmon habitat. Roughly four million cubic metres of material was removed from the creek within a stunning ten minutes. An event that would naturally have consumed thousands of years, should the stream have continued its normal flow.

 

The landslide scoured the Elliot Creek bed, creating this canyon, after an initial outflow into a glacial lake triggered an outburst flood. (Bastian Fleury/49 North Helicopters)

 

 Members of the Homalco First Nation who brought their intimate knowledge of Elliot Creek's salmon habitat, contributed to the research. Landslides, while not uncommon, are known to have carved the landscape of continents for millennia creating or diverting water bodies and rivers.

According to Professor Menounos, several factors would have occurred for the slope's instability and the landslide to have eventuated. Deglaciation, however, is being pinpointed as an accelerating cause of landslides. Scientists now have the required research methodology and accumulated data to map topography under glaciers, allowing them to estimate such events, inclusive of new lake formations.

Study: A retreating glacier in a remote British Columbia valley caused a massive landslide that crested a 100-metre-tall tsunami, wiped out kilometres of salmon habitat and was detected as far away as Australia. ElliotlakeToday