Scientists are using a microwave imaging sensor to monitor Turtle Mountain. ((CBC))

The Alberta government has installed a new piece of equipment to monitor geological movements on a dangerous mountain, part of which collapsed in 1903, killing 70 people in the town of Frank.

It was just after 4 a.m. on April 29, 1903, when an estimated 30 million cubic metres of rock slid down the east face of Turtle Mountain and into Frank, about 250 kilometres south of Calgary. The infamous event became known as the Frank Slide.

Today, as part of a multimillion-dollar monitoring program by the Alberta Geological Survey, scientists have installed a new $250,000 microwave imaging sensor to give warning should another catastrophic landslide seem likely to occur on Turtle Mountain.

A matter of time

Some experts believe it's just a matter of time before another major landslide occurs. Geological surveys in 1933 and 2000 suggest another five million cubic metres could tumble down the side of the south peak of Turtle Mountain, destroying everything in its wake. The province invested $1.1 million in equipment to monitor rock masses on the mountainside in 2003.

Engineer Corey Froese, the project lead on the Alberta Geological Survey's Turtle Mountain Monitoring project, said everyone in the world of geological engineering knows about the massive slide almost 107 years ago.

"Frank Slide is one of the most famous rock slides in the world," said Froese. "If you're a landslide specialist or an engineering geologist anywhere in the world, you know about this. The fact that your office is on the top of a mountain, it's pretty amazing. It's a pretty nice day job."

In the past six years, Froese and his colleagues have installed 80 sensors of various types above Frank, on and around Turtle Mountain.

2 large cracks

Each has a wireless antenna and its own power supply, but no protection from lightning strikes, snow and ice.

"It's an issue ... providing a reliable data stream to the base of the mountain," where the monitoring team has an operation base.

The new microwave imaging sensor is three kilometres from Turtle Mountain's peak and sits atop an old pumping station. Extremely sensitive, the new sensor is continuously bouncing signals off the mountain and two large cracks that have been discovered on the South Peak.

It complements the arsenal of existing equipment that is on the moutain to measure incremental movements in the rock mass.

Even from a distance, the scientists are able to monitor extremely minute changes in the time it takes for the microwave signals to echo off the rock face. Any change in the length of the signal indicates a movement on the mountain.

"If the time it takes for the signal to return changes, it means the mountain is moving," said University of Alberta geotechnical engineering professor Derek Martin, another member of the team who measures readings from the new sensor to those the team previously installed on the mountaintop.

If the devices reveal a significant shift in rock mass, a Code Yellow or Code Orange would be called and the public would be notified that a landslide is increasingly likely. In such a circumstance, an evacuation of the area would be called.


  • An earlier version of this story misidentified Derek Martin of the engineering faculty at the University of Alberta as Doug Martin.
    Jan 11, 2010 11:40 AM MT