A slow-moving landslide threatening the affluent Wyoming community of Jackson is picking up speed, and efforts to stabilize the area were called off because of safety concerns, city officials said on Friday.
The mass movement has displaced residents of several homes and two apartment buildings that sit near the base of the East Gros Ventre Butte which geologists said was slumping at a rate that this week increased to a foot a day from four inches.
"The fractured mass wants to slide down and gravity is pulling it down," Peter Ward, a retired geologic hazards expert with the U.S. Geological Survey, said on Friday at a town meeting.
"How it's going to fall apart nobody knows, but it's going to come apart," Ward said.
Evacuations from residences and several businesses below the crumbling hillside may go on for weeks as Jackson crews and utility companies work to prevent gas and power lines and a city water main from rupturing.
A project under way this week to buttress the base of the butte was halted on Thursday as rocks and gravel rained down, said Jackson Police Lieutenant Cole Nethercott.
"Right now, it's a life safety issue," he said.
The slide, about a mile from downtown Jackson, has cracked retaining walls, opened fissures in roads and bulged pavement, Ward said.
While landslides are common in the towering Teton Range near Jackson, best known as an international ski destination and for homes owned by celebrities such as actress Sandra Bullock and former U.S. Vice President Dick Cheney, they are rare in developed areas, he said.
Possible factors in the slide may be historic excavation of rocks and gravel at the toe of the butte, a major water leak in 2011, land development, recent rains and snow melt, Ward said.
(Reporting by Laura Zuckerman in Salmon, Idaho; Editing by Barbara Goldberg and Mohammad Zargham)