Two separate rock slides have carved large wedges out of Joffre Peak, east of Pemberton, B.C., raising safety concerns and alarming climbers and skiers who frequent the area, a geoscientist says.
Drew Brayshaw, who’s also a hydrologist, has climbed extensively in the area, and calls Joffre Peak “one of the crown jewels of mountaineering in southwest B.C.”
Part of the north face of the peak sloughed off early Monday with enough force to send debris more than four kilometres down Cerise Creek, east of Joffre Lakes Provincial Park, about 200 kilometres north of Vancouver.
Earthquake seismologist John Cassidy said in a social media post that the first slide was powerful enough to register on seismometers, but Thursday’s slide was even more powerful and was picked up by earthquake-monitoring equipment more than 300 kilometres away.
The second slide carried away a huge part of the north face of Joffre Peak, said Mr. Brayshaw, who specializes in landslides and debris run-outs, and has been following online reports of the slides.
“As soon as I saw the scar of that second landslide, which was right next to the first, it is obvious that the failure plane is continuing through the mountain, it is almost vertical,” he said in an interview.
“That strongly suggests that the next buttress over on the face of the mountain … I would say is more likely than not, going to fall off. The question is just when.”
Mr. Brayshaw cautioned that a more precise indication of risk would have to come from geotechnical engineers specializing in rock mechanics, and he said any danger from the tonnes of rock and debris in Cerise Creek would also have to be clarified by experts on the ground.
The ministries of highways, environment and forests, as well as Emergency Management BC had not commented Friday, while the Squamish-Lillooet Regional District said it was up to the provincial government to order a geotechnical assessment of the area.
The slides occurred on parts of Joffre Peak facing away from Joffre Lake Provincial Park and its world-famous, turquoise-coloured lakes.
Mr. Brayshaw said the debris run-out wouldn’t affect the park, but he said the loss of the north face was devastating for back-country enthusiasts.
He said at least three of what he would consider the top-20 ice-gully or alpine-rock climbs in southwestern B.C. had been lost to the slide, along with two of three couloirs, or narrow gullies, sought after by British Columbia’s growing community of extreme skiers.
“In terms of alpine climbing, that is comparable to if the grand wall of the Squamish Chief fell off and was gone. It’s that much of a loss,” he said.