Butte crack has Jackson on edge
60 people evacuated and stores vacated as gravity prevails at East Gros Ventre Butte
JACKSON, Wyo. – While the devastation and loss of human life from the mudslide in Washington state has been exceptional, mudslides in mountain areas are common enough.
So are avalanches, floods, and rolling rocks.
After two big winters of heavy snows in the early 1980s, water-saturated soils in Colorado began sliding. Homes were mostly spared, but narrowly, at an old mining town called Red Cliff. A hummocky hill called Meadow Mountain belched mud onto Interstate 70, closing the highway for the better part of a week.
At nearby Vail, destabilized boulders tumbled into a house in that city’s Booth Creek neighborhood. At another neighborhood, Potato Patch, one house slid into another.
Jackson Hole doesn’t have to look back several decades for muddy precedents. Three years ago, a mudslide blocked the highway that hugs the Snake River for three days. Workers commuting from the exurban areas of Alpine had to take an hour-long detour.
Now comes geological instability within the town of Jackson: a crack in the town’s butte. On one side, East Gros Ventre Butte defines the town, and a resident there in December noticed the wide crack in the soil.
On April 9 , after new evidence of movement, the town ordered evacuation of 60 residents. As well, two restaurants, a liquor store, and a Walgreens were vacated on the slim chance that the hillside would let loose. Cracks were visible in the hillside and the movement stretched power lines and buckled pavement in a parking lot.
The Jackson Hole News&Guide reports that a landslide specialist flown in from Oregon concluded there was a relatively small chance that the soil would “lurch” and fall onto the Walgreens below. “I can’t rule out that there will be a big lurch, but it’s not likely,” said George Machan, of Landslide Technology.
On April 14, the Jackson Council voted to spend $700,000 to create what the News&Guide described as a “massive weight” in the parking lot at Walgreens, to temporarily counter the force of the slow-motion earthen slide.
Of greatest concern to Jackson officials is potential rupture of a waterline that delivers one-third of the water consumed in the city of 10,000 people. If broken it would flood the town with 2 million gallons of water in 30 or 40 minutes, said Larry Pardee, public works director.
Friday morning, April 18, a house was broken in two, after the above-story was published in the e-magazine version of Mountain Town News.
For updated reports, see the Jackson Hole News&Guide report from Monday morning. The newspaper’s Angus Thuermer tells of a rumpled asphalt, a cockeyed water-pump house, and a looming cliff scared by rips in its face after a movement of 10 feet on the hillside. “Danger looms for some of the more than 200 workers engaged in the emergency project, especially those who venture into ‘the emergency area.” The Christian Science Monitor also has an Associated Press report from the scene. That dispatch has George Machan, the landslide specialist, reporting a movement of one inch a day that he expects to accelerate. The Town of Jackson website has photos and occasional status reports.
Also, see a summary of thoughts about floods, mudslides, and natural disasters in the Rocky Mountains, see this story.