Mountains seem permanent. Trees grow, ice melts, and river courses change, but, from a human perspective at least, mountains sit still. Until they don’t.
Landslide Lake is one of the few places on Vancouver Island where the evidence of that earthquake is most obvious. Deep in the interior of Strathcona Provincial Park, 11 kilometres up the Elk River Trail from Highway 28, the lake sits beneath a wall of sheer rock: Mount Colonel Foster.
It’s probably my imagination, but every time I stand on the lakeshore and stare up at the mile-wide and kilometre-high rock face, I swear it sways. I feel like any of its six summit towers could topple at any minute. History shows they could.
The 1946 Vancouver Island earthquake
At 10:15 a.m. on Sunday, June 23, 1946, an earthquake rippled out from under Forbidden Plateau. The 7.2 magnitude quake, one of the most powerful ever recorded on land in Canada, rocked central Vancouver Island and was felt as far away as Kelowna, Prince Rupert, and Portland, Oregon.
By luck and circumstance, the human impact was mostly minor. The closest call probably came at Courtenay Elementary School, where a chimney collapsed into two classrooms; if it had been Monday morning, the falling bricks would have landed on 60 kids. Instead, only two people died: a man drowned near Deep Bay when his rowboat was swamped by an apparent tsunami and another died in Seattle from a heart attack.
“However, in the mountainous region of Strathcona Provincial Park the earthquake struck with devastating force,” writes local historian Lindsay Elms at beyondnootka.com.
Eyewitness accounts
Soon after the Vancouver Island earthquake, the Royal Astronomical Society of Canada dispatched seismologist E.A. Hodgson to investigate the damage. His report for the society’s journal detailed personal accounts and his own observations.
H.R. Treherne, who was working on a farm in the Kitty Coleman Beach area, told Hodgson: “I was working on a fence and facing the sea, when suddenly, down the hill, the earth looked like a large snake coming up the hill, yet where I was standing was perfectly still for a second or so. After the tremor reached me, the roar commenced, tops of trees fell and bedlam was let loose.”
When Hodgson arrived in Campbell River on July 6, he found that the town’s namesake river “became muddy at the time of the earthquake and was still about as muddy as the Fraser [River].”
Something big had happened upstream in Strathcona Provincial Park. There are no accounts of anyone being in the mountains at the time of the earthquake, and Hodgson did not visit Strathcona or the lake, but geologists since then have pieced together what happened.
The Mount Colonel Foster landslide
High on Mount Colonel Foster, the earthquake cracked off a 365-metre-high chunk of the North Tower. Approximately 1.5 million cubic metres of rock—the equivalent of the entire Empire State Building and then some—tumbled off the mountain. About half came to rest in the basin immediately below, while the rest trundled down a steep hillside towards what was then called Lake Colonel Foster.
The two-million-tonne cannonball created an epic splash. A wave sloshed 50 metres up the opposite shore. Another crested the lake’s rim by 20 metres and firehosed down the Elk River Valley, ripping out old-growth trees and scouring the forest floor down to bedrock. Soon after, the lake was renamed Landslide Lake.
What’s visible today
Eighty years later, the earthquake’s impact remains obvious, though the first signs are subtle. About nine kilometres up the Elk River trail, the open, old-growth forest quickly transitions into a claustrophobic stand of younger trees. Ten minutes later, the trail suddenly pops out into the open. The regenerating shrubs, rushing creek, and mountain setting disguise the exposed bedrock. But at Landslide Lake it is impossible to miss.
On the eastern shore is a gash of exposed rock cutting through the forest. And directly above, near the top of the North Tower, is an obvious scar of grey rock on an otherwise dark wall. This is the source of the landslide.
Geologists have identified other landscapes on Vancouver Island likely created by the earthquake. But Landslide Lake remains the starkest reminder of the 1946 earthquake—and the awesome power unleashed when mountains move.
Check out our article from Comox Valley Collective Vol. 21 on The Big One.
