A slow-moving landslide on Yakima's Rattlesnake Ridge continues to move, 16 months since large cracks in the hillside were first discovered.
The earth is moving at a rate of 0.7 feet per week, according to the Washington Department of Natural Resources. That's significantly slower than the rate of 1.5 feet per week the slide was moving as of May 2018.
Large cracks above a quarry were first discovered in early October 2017, suggesting the potential for a landslide. Since then, mining operations have stopped and monitoring instruments were installed.
The Yakima Herald reports that recent heavy snows should not threaten the stability or speed of the 8-million-ton landslide, according to Stephen Slaughter, DNR landslide hazards program coordinator.
DNR classifies the movement as a translational landslide, composed of blocks of basalt sliding on a weaker sedimentary layer. Geologists and engineers believe the landslide will continue to move south, with material accumulating in the nearby quarry.
While monitoring continues, DNR said very low-probability scenarios where the landslide could mobilize quickly and reach I-82, impacting homes south of the quarry or potentially reaching the Yakima River.
DNR acknowledged no one knows for certain what could happen with the landslide, but plans are in place in the unlikely scenario the slide threatens humans or homes.
