Mud and debris fills a valley after a landslide occurred near Meager Creek Hot Springs north of Pemberton, B.C., on August 6, 2010.Darryl Dyck/The Canadian Press
Two hikers missing in the aftermath of a massive rock avalanche in Pemberton have been found, away from the immediate area of a landslide that is registering as one of Canada's worst.
Police confirmed Saturday that Vancouver firefighters Mark Nitychoruk and Jason Pruniak were located after police and search-and-rescue teams followed a hike plan the men had left with friends.
Police had been searching for the pair since an unattended red sedan was found near Birkenhead Lake on Friday. The men had parked there with plans to hike to a Toyota Echo 35-kilometres west of Pemberton, said RCMP Sergeant Shawn Lemay.
While they were hiking the avalanche hit, cutting off access to the second vehicle. The hikers were found near Aragorn Mountain Saturday and were airlifted to safety.
Their safety was confirmed a few hours after police lifted an an evacuation order for 1,500 residents near Pemberton
The evacuation alert, and corresponding flood warnings, had been issued on Friday after a massive avalanche dammed up creeks and shot debris across a valley near the town.
The slide was so huge it will likely go down in the history books as one of Canada's largest, according to a landslide expert.
"The field estimate for this landslide is 40 million cubic metres, which is bigger than [the Frank slide]and slight smaller than Hope," said Rick Guthrie, the Ministry of Environment geomorphologist who was tasked with assessing the danger of the slide.
"That makes it the size of Canada's big historical avalanches."
The avalanche started at the peak of jagged Mount Meager, about 70 kilometres north of Pemberton. The rock slide travelled 10 kilometres to the confluence of Meager and Capricorn creeks, and stopped Meager Creek from draining into the Lillooet River.
Instead, up to 3-million cubic metres of water pooled up behind the natural dam of debris and, by Friday night, it was threatening to breach the barrier and send an enormous flood into the Pemberton Valley.
The threat prompted emergency officials to force 1,500 people from their homes late Friday and put another 2,500 people on evacuation alert.
The evacuation alerts and orders were lifted Saturday morning local time.
On Friday, Mr. Guthrie said the growing lake looked like it was ready to bust through the dam within hours at a speed of 1000 cubic metres per second.
"That's a big flood on the Lillooet River," he said given the inflow of the creek was 32 cubic metres per second.
The following morning, emergency officials have learned the breech was a gentler one.
"Meager Creek did release water, but by way of cutting a new channel," said Leslie Lloyd of the Squamish Lillooet Regional District. "Early indications are that it is at fairly average flows."
The flow peaked around 3 p.m. Friday night, according to Mr. Guthrie, and by 5 a.m. there was only a small rise in the Lillooet River's water levels.
"We've and confirmed that the lake that was behind this dam has now drained and there is no remaining hazard from a dam failure at this time," Mr. Guthrie said Saturday morning.
The area around Mount Meager is still extremely volatile however, warned Mr. Guthrie. Tension cracks could lead to subsequent, smaller landslides. "We don't recommend that anyone curious is in that vicinity, at least on the ground," he said.
"It's a very, very unstable complex," said Pemberton Mayor Jordan Sturdy. "Always has been and will continue to be. It's not unlikely that these events could happen again in the future."
The Pemberton area has been deemed one of the most slide prone areas in Canada.
John Clague, an earth sciences professor at Simon Fraser University, said there have been six such slides at the site of Friday's incident since 1931. The most recent, before now, was in 2009.
"This landslide is big, but not unique," he said. "The area is prone to slides. It's a dormant volcano with high, fractured lava leading to rocks that are prone to slides. That, with deep slopes, is a recipe for slides."
Immediately after the slide, the RCMP evacuated eight people who were camping near the Meagre Creek hot springs by helicopter.
Five other people who work at a local pumice pit refused to leave the area adjacent to the avalanche, said RCMP Sgt. LeMay. The group remained camping on high ground near the pumice pit on Friday night.
RCMP shut down the roads into Pemberton Meadows and the Lillooet River Valley when the official evacuation order came down on Friday night.
More than 70 per cent of the people under evacuation order had left by Saturday morning, said Ms. Lloyd.
But many farmers in the fertile valley opted to stay behind, including Pemberton Mayor Jordan Sturdy.
"It's incredibly stressful," he said of the order. "It's not so much the evacuation order as the actual issues around flooding. They can be devastating and catastrophic in terms of investment. It's your livelihood. It's your life."
Mr. Sturdy said he had a good sense of the scale of the event and the risks. He said he had seen similar estimates about water levels in the past and decided to stay because he believed the flood would likely mean high water, not a raging river.
Instead of packing up and shipping out, he focused on getting his animals - sheep, chickens, pigs and ducks - to higher ground.
Ms. Lloyd, who was helping to coordinate the evacuation, would not comment on the mayor's choice, only saying that people refusing to evacuate is "par for the course".
Matt Van Loon lives on a ranch downstream from the giant dam created by the slide, and described the sight as unbelievable. "It's something that you are going to see once in your life and never again," he said.
Mr. Van Loon's mother and two siblings fled to safety Friday night, but he and his father, Marty, stayed back to tend the ranch, while keeping a close eye on the water levels in the Lillooet River which border their farm.
"We'll keep the keys in the car," said Marty Van Loon. "Supposedly it will take five or six hours for the surge of water to get down this way."
The men had already moved their cattle behind a small dyke that guards against the Lillooet River.
"If the river dams up and then lets go, then we are going underwater downstream," said the older Van Loon. "That's what worries me."
The farm has been devastated by a landslide before, dumping silt and debris that ruined the fields. Mr. Van Loon said it took five years for the farm to recover.
Cleaning up the destruction left by this landslide to local infrastructure, forest roads and popular tourist destination Meager Hot Springs will be an uphill battle for the provincial government.
Mayor Jordan Sturdy said options for clearing the mix of soil, rock and snow in the slide are limited by the lack of stability in the area of the slide. "It wouldn't take much to drop another million cubic metres of the face of the peak that slide."
"You are talking an event that is 10 kilometres long and half a kilometre wide," Mr. Guthrie said.
"That's not going to be cleaned up very easily. The entire area will be really, really saturated. You won't be able to stand on the debris. You'd sink to your neck or further."
With files from Ian Bailey