JACKSON, Wyo. —
But other factors appear to be in play on Jackson’s East Gros Ventre Butte, a small mountain that looms over the west side of town, its base dotted with homes and businesses.
The area of the landslide has been graded for roads and businesses in recent years, including a new Walgreens. That could have weakened the hillside and set the stage for the landslide, although the precise trigger remains under investigation.
Jackson resident Rick Johnson lives less than a quarter-mile from the slide area along the same south-facing butte. He said a retaining wall on his property has been shifting in recent years, but he had not given it too much thought until the slide started just down the road.
As he watched workers at the top of the slide area taking measurements of the previous night’s movements, Johnson said he had no doubt that the natural geologic forces at work were amplified by the construction at the foot of the mountain.
“I think they are just messing with Mother Nature and they didn’t think of the long-term consequences,” he said.
Unlike an earthquake or tornado, landslides typically are isolated and don’t affect large swaths of territory. Yet they consistently rate among the costliest, most frequent and deadliest natural disasters in the U.S., said David Montgomery, a geology professor at the University of Washington in Seattle.
They occur in all 50 states, kill 25-50 people a year and cost $1 billion to $3 billion a year, he said, citing a 2004 National Research Council report.
Landslides in scenic, mountainous areas like Jackson are a lot like the wildfires that occur in the same areas. Both hazards are natural events that present more of a problem when people move in and build subdivisions or shopping areas.
“When you add it up, it’s actually a major geological hazard,” Montgomery said. “As more people move into more mountainous environments, the opportunities for interactions between human infrastructure and people, and landslides, increase.”