We Did The Math: When The Rattlesnake Ridge Slide Will Occur
Well, you should really get used to the nickname "Crackima," because the state's most famous crack is here to stay.
At least, according to geologists with state agencies and consulting firms studying the ridge slide.
As you know, we are talking about approximately 20 acres of basalt, aimed at a little neighborhood along I-82 3 miles south of Yakima near Union Gap.
According to the fact sheet on the slide, the mass of earth is still moving at a rate of about 1.5 to 1.7 feet per week in a southward direction. Geologists say the type of movement expected is a translational landslide composed of blocks of basalt sliding on a weaker sedimentary layer.
Despite earlier worst case scenarios that filled the minds of many area onlookers and commuters, the geologists and engineers monitoring the landslide suggest that the most probable scenario is that the landslide will move south and accumulate into the quarry.
Which would make sense, since it is fairly obvious the quarry caused the slide in the first place when the previous company exposed the toe and cleared the surround foundation. But that's not the big question on every commuter's mind when they are on that scary s-curve at 4:00 am in the morning.
The big press conference this week was supposed to ease minds, but we still want to know WHEN WILL IT FALL?!
Under the current projections, rockfall is expected to continue at its current speed, so given the height of the ridge and time we can figure that part out. Given the weeks in the year, we take 52 weeks times 1.7 we can determine a rough guesstimate that the slide will move around 88.4 feet per year. Given the height of the drop on the topographic maps, we can roughly estimate that the slide will take 5-8 years to slowly fall.
That excludes a change in momentum or something as ominous as a huge dumping of snow or a bored redneck and his 4X4 with a mobile camera and a dream charging up the face of the ridge that destabilizes it. Or a random Washington, Ring-of-Fire tremor.
So, don't worry when driving by our big crack in the gap. It won't fall for another five years or so. Like a lot of things here in the Yakima Valley, it's gonna get there eventually, like a dusty pick-up truck going 55 and weaving because of the bad shocks on Highway 97.
Just keep in mind, no one knows for certain exactly when the slide will occur. This is a guess, the whole thing could come down tomorrow for all we know for certain.