City could face ‘lake tsunami’

Shuswap Lake: Professor suggests major rock slide has the potential to cause wave damage.

Chehalis Lake: A view of a massive landslide at the remote lake

Large destructive waves are a problem that most would think should only concern those who live on the ocean, but an SFU professor says lake communities should be concerned as well, and Salmon Arm could fall victim.

Professor John Clague studies landslide generated tsunamis, which can occur in lakes.

“I got engaged in this when we had a very large event of this sort at a lake called Chehalis Lake,” Clague said.

Two million cubic metres of earth slid down a hillside at Chehalis Lake in 2007 creating a displacement wave that devastated the surrounding shoreline, destroying trees as far as 25 metres from the water’s edge.

“The thing that startled us is the size of the displacement wave,” Clague said.

Chehalis Lake was home to several forestry service campsites, however the campsite was vacant so no one was injured.

“I did mention Shuswap Lake (in the study), not because there’s an obviously threatening slope there, but because there are large rock faces that border the lake. If there ever were to be a landslide there then you’d have a big problem in a place like Salmon Arm,” Clague said.

Calvin van Buskirk, local engineer and geoscientist, agreed there is potential for large landslides in the Shuswap area, but added only a truly massive landslide has the potential to cause a lake tsunami.

“There are lots of large-scale landslide features around Shuswap and Adams Lakes. It’s just a question of whether they fail catastrophically,” he said.

Van Buskirk offered the example of a slide from Bastion Mountain in December 1959 as one that although large, did not cause destructive waves. The British Columbian newspaper reported the 1959 slide was large enough to cover approximately 1,000 feet of what is now Sunnybrae-Canoe Point Road with as much as six feet of rubble, temporarily isolating eight families.

The article in The British Columbian refers to a legend of a large “Tidal Wave” caused by landslides which destroyed a First Nations village on the Shuswap sometime in the 19th century.

Although Clague says there is no indication that Bastion Mountain or any other large rock faces on the Shuswap are unstable, he believes that another tsunami-like event caused by a large rockslide is inevitable in B.C.

“Given the amount of rock faces we have adjacent to populated shorelines it’s only a matter of time before something injurious or damaging happens,” he said.

With the exception of BC Hydro monitoring rock faces near their reservoirs to prevent a potentially catastrophic dam failure, he wasn’t aware of any large scale efforts to prevent large rockslides at lakes, Clague said.

Very slow movements of slopes precede their failure, making damaging landslides detectable and possibly even preventable.

There is a satellite tool for measuring slope movements called Interferometric Synthetic Aperture Radar (INSAR), he said.

INSAR is used extensively in Norway, where over 170 people have died in the last century from tsunamis in fjords, he added.

Van Buskirk isn’t aware of anyone studying or monitoring rock formations near Shuswap Lake


Just Posted

In photos: The 27th Annual Salmon Arm Roots and Blues Festival

Images from Friday evening and Saturday at the festival grounds.

Summerland cannabis shop receives approval in principle

Inspection now required before Green Gaia may sell cannabis

North Okanagan-Shuswap Liberal candidate responds to Trudeau ethics report

Prime Minister’s immediate response to commissioner’s findings appreciated

Shuswap tow truck operator sees high number of collisions this summer

Drivers encouraged to “loosen up behind the wheel, smarten up and read the road”

QUIZ: How much do you remember about Woodstock?

Weekend music festival in Bethel, New York, was held 50 years ago

Canada ‘disappointed’ terror suspect’s British citizenship revoked

Jack Letts, who was dubbed “Jihadi Jack” by the U.K. media, has been detained in a Kurdish prison for about two years

Fire departments extinguish suspicious wildfire near West Kelowna

Crews established a fire guard and knocked down the blaze before it grew to one hectare.

Chrystia Freeland condemns violence in Hong Kong, backs right to peaceful assembly

There have been months of protests in the semi-autonomous region

B.C. VIEWS: Log exports and my other errors so far in 2019

Plastic bags, legislature overspending turn out differently

15-year-old boy drowns after midnight jump into Okangan Lake

The RCMP and BC Coroners Service are investigating the drowning.

‘It’s just the freedom:’ Paralyzed Broncos player pursuing life on the water

The former Humboldt Broncos goaltender, who started in the net when he was nine, was paralyzed last year

Canadians killed in Afghanistan honoured during emotional dedication ceremony

One-hundred-fifty-eight Canadian soldiers died during the mission

It’s snow joke: Up to 30 cm of snow expected to fall in northeastern B.C.

Alaska Highway, Fort Nelson to be hit with August snowstorm, according to Environment Canada

Most Read