Rock slides that shook Squamish linked to climate change, expert says

The community of Squamish, B.C., was shaken by two rock slides in the span of 24 hours on Monday, with a massive slab of granite shearing off a section of the Stawamus Chief and smashing to the ground early in the morning.

The Chief is a massive granite dome south of the town, popular with tourists and climbers.

The first rockfall, which occurred at 1:34 a.m. PT and was captured on webcam, left an iron-tinged scar on the rock face after a flourish of sparks and dust plumes. A smaller slide hit at around 4:45 p.m. PT near Angel's Crest Trail, as people lined up to vote in the federal election.

Alexis Birkill, who runs chiefcam.com, recorded the rocks as they crashed down from Upper Zodiac Wall.

No injuries were reported, but B.C. Parks and Squamish RCMP are urging people to stay clear of the area where the Western Dihedrals meet the Grand Wall.

The climbing walls are closed while geotechnical engineers work to ensure safety. Closures are expected to last through winter, with fears that rain, then freezing temperatures, may trigger more debris falls from the ancient rock face.

Some experts say climate change may be accelerating the number of slides that are often triggered by heat waves followed by rain. Extreme temperatures this summer may have caused the rock to expand and then contract again in the cold, creating stress fractures. Once weakened, heavy rain helped loosen the rock.

Gio Roberti, an avid climber and climate change risk expert at Minerva Intelligence Inc., an engineering company, said the larger rock slide triggered two days after Friday's 100 millimetre rainfall.

"It took some time for the water to percolate through all of these cracks and to push the pillar off the wall," said Roberti.

The rumbling rock cascade registered on a local seismograph. The last slide this big on the North or Zodiac wall was reported in 2015. Five rockfalls have been reported this year, with three others occurring on the Grand Wall in late June and July.

Rumble like thunder

Anne Bright was awakened by the rumble of what she thought was thunder or an earthquake shaking her home around 1:34 a.m. PT Monday morning.

Bright said it persisted for 16 minutes. 

"Both of my cats' tails were really puffed and they were freaked out so I knew something was going on," she said.

Bright said when she looks up at The Chief on a full moon night, she usually sees the headlamps of campers at the top of the rock dome. Thankfully, rain had kept campers away.

Climber Micah Handell believes he was the last to climb a massive angular slab of granite before it sheared off early Monday morning. He took pictures of himself atop a section of rock on the Borealis route back on Aug. 24, 2021.

But he said that he was quick to dismount after seeing the deep, menacing fissure between the rock and the face of the monolithic Chief.

"I thought, man I'm happy I got to climb this route before this thing falls off," said Handell.

Roberti warned against any further climbing on the rock face of The Chief.

He said he is not surprised people want to be the last to stand on a slab that's threatening to fall.

"Ya, people do all sorts of weird things," said Roberti.

Starting this month, a research group out of Simon Fraser University will be using light detection and ranging (LiDAR) and laser beams to study the rock structure and evaluate how safe and stable its various sections are.

They hope to place seismographs to pinpoint higher risk areas.

Paul Adam, manager for citizen's science initiatives at Simon Fraser University's Centre for Natural Hazards Research, says "flakes" of rock falling off the Stawamus Chief are not new, and believes that blaming it on climate change is a "stretch."

But he agreed, climbing the monolith is out for now.

"At this point in time I'd probably give it a little bit of time to settle."