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Landslide risk spurs action in Pemberton

Mount Meager slides identified as potential natural hazard



Local officials in the Pemberton area are looking at putting in early warning devices to alert locals in case of a massive landslide from Mount Meager.

The move is being considered following the release of a study by government and private geoscientists and engineers suggesting that there is a risk that a catastrophic landslide could come off the mountain without any warning and sweep down into the Lillooet valley.

“We will meet with the authors and consider what the options are and it may be that there is a possibility of looking at early warning type of technology,” said Pemberton Mayor Jordan Sturdy.

There have been several large events in the last century, with one landslide in 1975 killing two people. In the last 6,000 years there have been three landslides which have resulted in debris flows that have reached all the way to the Pemberton Valley.

“It is a very unstable mountain,” said Professor John Clague of the Centre for Natural Hazard Research at Simon Fraser University, a co-author of the report.

“In fact it is considered one of the most unstable mountains in the country because it is a dormant volcano. The volcanoes are typically unstable and susceptible to landslides.”

Clague said he and his colleagues felt compelled to publish and release their findings when their research showed that the landside events on Mount Meager were not one-off events.

“We were wanting to document the history of the valley in that area and what we found there was quite startling,” said Clague.

“We found evidence of what we call debris flows, volcanic debris flows, that had travelled all the way from Mount Meager more than 30 kilometres… down the valley to a populated area.

“So we began to think in terms of the very serious risk to the community.”

Like many natural hazards now being investigated in Western Canada there is no real way of knowing when disaster might strike. The landslide could happen next week or in 1,500 years.

Sturdy pointed out that there are populations living with natural hazards all over the Lower Mainland so that this one must be considered as part of the big picture.

“There is a risk with developing a building in Richmond, with its tidal surge and liquefaction so there are risks all over the place, so you have to keep it in perspective,” he said.

“Any future residential development in this community will be for the most part off the valley floor and up on the hillside — that is what is in our official community plan and in the regional growth strategy.”

The Squamish Lillooet Regional district took out ads in the local papers to inform people of the now assessed risk and has put copies of the study on their website, www.slrd.bc.ca, and in the pubic library.

“It (Mount Meager) has been assessed now so the (SLRD) Board will have to think carefully about what action we will take,” said SLRD administrator Paul Edgington.

“But the first and most important step was to just let the public know that it is there so they can make their own personal assessment without intending to panic people.”

There are no risk assessment protocols for British Columbia or Canada so scientists based their risk assessments on those of other nations including the U.K. and Australia.

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