B.C. Parks has closed several climbing areas on the popular rock wall known as the Chief following a significant rockfall early Tuesday morning.
The areas along the Grand Wall and Western Dihedrals are closed until further notice, according to the provincial agency.
Squamish RCMP said there were no injuries.
Paul Adam, the manager at the Centre for Natural Hazards Research at SFU said that this is one of the biggest rockfalls on The Chief in the last 60 years. Adam says he suspects it is due to thermal expansion, resulting from the recent hot weather.
According to Adam, rocks expand when they heat up during the day and subsequently contract in the cooler nighttime temperatures. This causes cracks and spaces to form and can cause chunks of rock to break off.
A 2016 study looked at a similar case of rockfalls as a result of heat at Yosemite National Park in California. The study shows these types of rockfalls typically happen during the hottest times of the day.
Adam stated that while it is more likely for expanded rocks to break off during the day, it is still possible for this to occur at night.
Perry Beckham, a climber who has lived in Squamish since the late 70s, said this is the biggest rockfall he has seen during his time in Squamish. Beckham said he spoke to an eyewitness on Tuesday morning, who told him that the rockfall happened just after midnight.
Beckham said the area where the rocks fell is a very popular climbing spot.
"It's hard to imagine there wouldn't have been fatalities if it had happened during the day."
Adam said while it is hard to predict exactly where and when rockfalls are going to occur, he wouldn't be surprised if a similar incident occurs in the heat wave that is expected over the next few days. He recommends that climbers find an area that is constantly shaded throughout the day.
"The less direct sunlight the better… I wouldn't be out on the Grand Wall right now."
The main hiking trails, including the Backside Trail, have not been impacted.
Area prone to rockfalls
This comes just a month after a similar rockfall in the same area on the Chief, which had already resulted in the closure of some of the Grand Wall.
"This one eclipses the earlier rockfall that was a concern, it's on a much different scale," said Beckham.
Squamish resident and climber Logan Farrow said he watched smaller pieces in the same area slowly come down in the days before. Farrow said after this rockfall and the incident that occurred last month, climbing the Grand Wall is currently a "no go" for him.