New drone video shows Rattlesnake Ridge crack

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The Washington State Department of Natural Resources posted a new drone video from Yakima's Rattlesnake Ridge landslide this week.

The video was taken Monday by geologists. The crack emerged back in October, and the hillside has been slipping at a rate of 1.5 feet per week since late December.

Experts say a landslide event could happen sometime between late January and early March.

Yakima County, the city of Union Gap, and the city of Yakima have all declared it a disaster area in response to the slide.
 

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"The honest answer is no one knows for certain. There are a number of possibilities. The most likely scenario is that the landslide will continue to slowly move to the south, where the landslide mass will fall into the quarry pit and accumulate. Monitoring data suggests most of the mass will remain in the pit and on the hillside," the Washington state Department of Natural Resources said on its website.

Some rocks are expected to fall and reach nearby Thorp Road, but not Interstate 82 or the Yakima River.

They say "less likely scenarios" are that the landslide moves beyond the quarry and damage houses or run out beyond I-82. "A landslide that moves west and blocks I-82 and the Yakima River is extremely unlikely."

Geologists have been watching the situation since early October when state geologist Dave Norman says a rock quarry company, Columbia Asphalt and Gravel, contacted the DNR to say they’d found a crack in the wall of the quarry, correlating to a growing crack that was threatening to bring down part of a hillside above I-82.

Homes in the area have been evacuated and the quarry company is paying to put them up in hotels. Old steel shipping containers full of heavy concrete barricades are protecting the interstate from falling rock, but may not prevent a full-blown slide from reaching the highway. 

The slide is being monitored by laser to measure movement and by seismometers which are recording cracks and other sounds.