12 April 2016
The Renfrew County Landslide
At about 2 am on 29th March 2016 the Renfrew County landslide occurred near to Horton Township, west of Ottawa in Canada. This landslide, which is reported to have had a surface area of 10 hectares, slipped into and blocked the Bonnechere River. Various local news agencies have images, of which the best overview is on the Ottawa Citizen:
The level of the impounded water rose by 7 m, damaging a cottage, a hunting camp and a hydroelectic plant, amongst other impacts. After about seven hours the dam breached, releasing a flow at a rate of about 250 cumecs (cubic metres per second).
“There are definitely ancient, large landslides that are mapped in that area,” said Greg Brooks, a landslide expert with Natural Resources Canada. “This is another one…You can’t stop them. When they’re going to happen, they’re going to happen.” He said the land includes a lot of leda clay — the former bottom of the ancient Champlain Sea, which is prone to collapsing suddenly, especially when it is sodden. Early spring, while the ground is thawing, is prime time for these landslides. The size, though dramatic, isn’t a surprise, Brooks said. “Sensitive clay landslides can easily be that size, or larger.”
This appears to be the site of the landslide:
That bulge into the river might be the sign of some previous instability perhaps?
The best information and data about the landslide sits on the Twitter account of James Power, a Paramedic Drone Consultant (who knew there was such a job?) with Renfrew County Paramedics. His twitter handle is @IASF07. He, and his colleague Steve Osipenko (@osipenko_steve) have tweeted some great images and videos of the landslide, taken by his drone, including this photograph: