April 29th, 2016 ~ Vol. 85 No. 17
Big stone on top of Turtle Mountain could be getting ready to drop
Crowsnest Pass Herald Front Page
Vyk Harnett Photo
Rocky ridgeline of Frank Slide on Turtle Mountain.
Pass Herald Reporter
In a throwback to the 1903 slide that buried the town of Frank and killed between 70 and 90 people, a large boulder on top of Turtle Mountain might be getting ready to fall.

From June 20 to Dec. 5 the boulder, nestled between the southern and northern peaks of the mountain, moved a whopping 35 millimetres.

“We’re not 100 per cent positive but it’s probably getting ready to topple,” said Todd Shipman, manager of the Turtle Mountain Monitoring Project. “We’re hoping to focus on it to see if we can predict when that will happen.”

Sensors picked up the movement throughout all of last summer and into the winter. Shipman said these types of rock falls are common and present no danger to the public unless you happen to be standing in the rock’s way when it decides to drop.

“I don’t think it is a risk, although it looks big, but those things are happening all the time,” said Shipman.

“We’re going to keep an eye on it,” he added.

Except for that particular rock, things have been pretty quiet on Turtle Mountain since the Turtle Mountain Monitoring Program began over ten years ago. At the program’s open house on April 21, Shipman talked about the Turtle Mountain Monitoring System Transition Plan. This means the Alberta Geological Survey will no longer be on call 24-hours a day.

“Mainly because its costly and not appropriate for the level of hazard that we’re monitoring,” said Shipman. “Because if [the mountain] does move, we’d have weeks to plan a response.”

Previously, members of the monitoring team were constantly on standby, ready to spring into action in the event of another slide. On the advice of an expert panel of geologists and academics, and as a cost saving measure, the monitoring team will no longer be at the ready all the time.
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“If there’s movement on a Saturday and we came in early Monday morning, we would still be able to respond in a timely manner,” explained Shipman.

Danielle Wood, project manager, said the overseas labs that are constantly monitoring the mountain would have up to two days to contact the monitoring team if movement became apparent.

All their data is sent through cell links, radio links and internet links to the Frank Slide Interpretive centre and then to a central hub in the provincial building. It’s then sent to third party companies that monitor the data.

Wood said the relaxed alert level would save taxpayers up to $60,000 per year.

In the event of a slide their control centre would immediately contact the Alberta Emergency Management Agency (AEMA) who would then assume responsibility for a response.

The monitoring team has identified two faces of the mountain that could someday detach. One area of risk is on the south peak; the other is on the north peak, with both areas facing Frank and Hillcrest.

Models show that a south peak slide could threaten Highway 3, the railway, the river and the Hillcrest Ball Diamonds.

Such a slide could contain between 240,000 and 3.5 million cubic metres of rock, which is a drop in the bucket compared to the Frank Slide where an estimated 82 million tonnes of rock detached at once.

Shipman said the mountain has been moving between 1 mm and 2.3 mm per year since monitoring started in 2004. The mountain is at its most mobile during the spring/fall freeze thaw cycle. Anything less than 16 mm is considered low risk.
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He also said that a slide in the direction of Blairmore is highly unlikely.

“The way the mountain is built, and if you can imagine it as a cold piece of play dough, when you bend it, you get a lot of fractures on the stretched length of it. There are some factures on the western side of the mountain but the likelihood of a failure in that direction is low to nonexistent,” he said.

The monitoring project has been removing much of their equipment off of the mountain face since they’d probably be destroyed in the event of a slide.

The survey is increasingly relying on ground-based radar called InSar sensors, which measures movement by taking an image of the mountain face every six minutes.

They’ve enlisted Randy Rinaldi of Rinaldi Welding to do maintenance on their sensors when necessary.

“It’s been working,” said Shipman. “It worked through the whole winter and it didn’t shut down once.”
April 29th ~ Vol. 85 No. 17
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