An earthquake last week in the B.C. Interior may have set off a large-scale landslide in the Whistler backcountry, according to local safety officials.
The slide took place last Wednesday, Dec. 16 on Fingerpost Ridge, a sub-ridge of Mount James Turner, east of Lesser Wedge Mountain. Early analysis indicates the slide was roughly three to four kilometres long and 0.75 kilometres at its widest point.
No threat to the public has been reported, although the Squamish-Lillooet Regional District (SLRD) is urging backcountry users in the area to use caution and be aware of unstable slope conditions.
Ryan Wainwright, emergency manager for the SLRD, said it's likely a 3.6-magnitude earthquake that struck near Kamloops in the early hours of Dec. 16 set off the slide.
"We don't usually dedicate a lot of resources to (geological events) that don't have an impact on people, but I do know that it's an unusual time of year to have a landslide that's triggered by anything other than an earthquake," Wainwright said.
The size of the slide came as a surprise to Whistler avalanche safety expert Wayne Flann.
"I've never seen something like this happen since I've been here, where a huge ridgeline collapses and creates a huge landslide like that," he said. "It's quite a big event."
As the slide occurred in a relatively isolated area, the SLRD has no plans at this point to carry out any stabilizing work.
"Obviously if this becomes more of a problem and it starts happening on a regular basis, we'll probably work with the province to look at it," Wainwright said. "But I think it's just a one-off — it's just what happens."
Although this slide was likely earthquake-induced, Flann warned the region could increasingly see more geological events of this scale with the impacts of climate change in full swing.
"I think we will see (more major events) because, as the glaciers retreat, more rock becomes exposed and the rock is just not holding up anymore," he said. "There are a lot of places where the ice just hasn't stopped (melting). The melt in the summertime starts in June or July and goes right through the whole summer.
"We live in mountains that are actually quite fragile."