Stawamus Chief prone to rock slides, says SFU geologist
A Simon Fraser University geologist says he isn't surprised about the massive rock slide on the Stawamus Chief on Sunday because smaller pieces have been falling regularly for years.
"If you look at debris at bottom and the big huge rocks that climbers boulder on, it indicates a long history of pieces breaking off," says Brent Ward.
"It does happen ... it's just that it usually happens where no one goes and no one sees it," said Ward. "Here we had lots of eyewitnesses, we had video ... these sort of things happen all the time in B.C., but it's usually in remote areas."
Ward says the rock on the Chief is stable, but its jointing pattern can be a problem.
"The fracture patterns, these joints, are weak and over time, gravity is always acting on these slopes and it weakens it and it will eventually fall," said Ward.
Timing of rock slide notable
Ward says one notable aspect of this rock slide is the timing.
"Usually it's a freeze-thaw thing: Water freezes in the cracks at night, thaws in morning and then breaks off. Maybe the cold weather last week loosened it enough, and it was time for it to come off."
Ward says there is new technology that can scan a rock over a period of time and see where movement is occurring, helping officials anticipate rock slides.
"Here, I don't think it warrants the cost. It is a recreational area so people are not there all the time," said Ward. "But certainly if we had a housing development at the base of that cliff, it would likely be done."
Ward offered up some helpful tips to climbers and hikers who may be heading into the mountains this summer.
"Where it's jagged is probably where rocks have fallen down. Those areas where the rocks are smooth, those areas are not at risk of rockfall."
To listen to the full interview with Brent Ward, listen to the audio labelled SFU Geologist on Rockfall.
