A fourth landslide has hit Whitehorse.

On Tuesday, another large slide struck not far from the avalanche that closed Robert Service Way on Apr. 30.

Jeff Bond of the Yukon Geological Survey was at the scene just after the slide occurred.

He told the Star this morning he had been contacted by workers at the site who noticed more movement on the clay cliffs.

“They said a tension crack was opening up slowly.”

Bond was planning on installing a sensor in the location after the call. He and a colleague were working their way up the cliffs Tuesday when a section gave way.

“We missed it by five minutes,” he said.

The slide is in close proximity to a large slough that occurred last year, Bond said. It’s about the same size as last weekend’s two events (see p. 3), which were somewhat larger than the Robert Service collapse.

“It’s about 40 metres by 100 metres,” Bond said.

The latest slide is about 200 metres to the south of the slide that closed the road, Bond said. Like the one that occurred last year just slightly further to the south, this one didn’t threaten to come over the road.

Bond explained it’s in a section a little further away from the road, and not as dangerous.

As he did on Monday, Bond said the cause of the problems is an overabundance of ground water, likely from the high snowpacks over the last two winters.

Tuesday’s slide, though, didn’t contain nearly as much water as the others.

It’s in a heavily-wooded area, which would help absorb the groundwater. Some of the trees that were knocked down in the landslide are quite large, Bond added.

He doesn’t expect the escarpment to dry out until later this month – if the current dry weather holds.

Bond said he doesn’t think the current slide will affect the clean-up efforts, although that’s more a question for City of Whitehorse officials.

The slides, he said, are unusual in recent history, but are definitely not unusual in a bigger-picture historical context.

There’s ample evidence this happened before over the centuries, Bond said.

“The use of LIDAR technology, for one, shows us many past slides.”

The city has set up a network of sensors all over the escarpment, and is trying to get a sense of the daily movement, Bond said.

“There’s a team of people working on it.”

Mayor Laura Cabott told the Star late this morning the slide had been expected for weeks.

People monitoring the escarpment had been keeping an eye on a tension crack for some time, she said. It had reached four metres wide Tuesday morning before giving way.

This avalanche will not affect nor impede the work going on to try to reopen Robert Service Way in the next week or two, she added.