Old Fort, B.C., residents in holding pattern as landslide inches toward homes

An evacuation alert has also been issued for the outskirts of nearby Fort St. John, meaning anyone in that area should be prepared to leave at a moment’s notice.

Although the only road in and out of Old Fort has buckled, Pardy has been returning to check on his home and others using an ATV.

He said in a recent phone interview that he looked in on his house Thursday, adding it could be for the last time.

The Peace River Regional District posted a notice that day saying anyone found disobeying an evacuation order could face fines up to $10,000 or jail time.

The slide is surreal because you can’t see it moving even when you know it is, he said.

“It’s like when you look at the hands of a clock and you don’t see them moving, but you turn around and come back after five minutes and it’s moved five points over,” Pardy said.

Some residents in the area recall the 1973 Attachie slide about 40 kilometres away, he said. In that case, the earth slipped at a rapid speed, damming the Peace River.

Marten Geertsema, a research geomorphologist studying the Old Fort slide for the Forests and Lands Ministry, said it doesn’t appear to have too much in common with the Attachie slide.

He said scientists with the ministry and Westrek Geotechnical Services are monitoring the slide using laser light technology and helicopter surveys to figure out exactly what triggered it.

There are two slides underway, he said.

Debris from the main slide has blocked a channel in the Peace River near Old Fort and started to encroach on a nearby island. A large compression crack west of there has dropped five to six metres into the earth which could further destabilize or the westerly slide, Geertsema said.

The westerly slide is carrying a house and a lagoon that remains full of water with it, he said.

“It’s like having a pile of mashed potatoes on your plate and pushing it with a fork. You can have all sorts of little things on top of the mashed potatoes and they don’t deform but they’re still moving,” he said.

Even if the slide doesn’t suddenly slip, he said a slow moving slide can still sweep away a village.

“It can either hit a house and bulldoze them, or sometimes when the failure plane or rupture surface is really deep it can carry them away,” he said.

Peter Bobrowsky, a senior research scientist in landslides based at the Pacific Geosciences Centre in Sidney, B.C., said landslides are especially common in the Peace Region because of the history of glaciers forming and melting over tens of thousands of years.

That process creates three main layers of sediment that interact in a way that makes them vulnerable to sliding.

The least porous layer is where trouble occurs because it can get heavy with water when it rains, he said.

There have been hundreds of thousands of landslides in the Peace Region in the past 10,000 years, ranging from the size of a wheelbarrow to tens of millions of cubic metres, he said.

Hopefully, the landslide will stop before any real damage occurs to the homes, he said. But the can also start again and it’s hard to predict how long the break will be.

“It can be minutes, hours, days, years, decades,” he said.

“One of the advantages of a catastrophic failure is it happens, then they monitor it for a while to make sure there isn’t going to be anything else, and then they get to work cleaning it up, buttressing the slope,” he said.

— Story by Amy Smart in Vancouver

The Canadian Press

by Canadian Press

Old Fort, B.C., residents in holding pattern as landslide inches toward homes

What's Trending