Quantcast
Get breaking news alerts via email

Click here to manage your alerts
A house breaks apart as a slow-moving landslide in Jackson, Wyo. advances downhill on Friday, April 18. 2014. The slide has cut off access to a 60-person neighborhood and has threatened town utilities, including a water line. (AP Photo/Jackson Hole News and Guide, Angus M. Thuermer Jr)
Creeping landslide devouring part of Wyoming town
First Published Apr 19 2014 12:40 pm • Last Updated Apr 19 2014 12:40 pm

Jackson, Wyo. • A slow-motion disaster continued unfolding in the Wyoming resort town of Jackson on Saturday, as a creeping landslide that split a hillside home threatened to swallow up more houses and businesses.

The ground beneath the 100-foot hillside had been slowly giving way for almost two weeks before the downward movement accelerated in recent days.

Join the Discussion
Post a Comment

With rocks and dirt tumbling down, officials suspended efforts to shore up the slope and said they were uncertain what else could be done.

"When is it going to go? How long is it going to last? These are the questions we just can’t answer and they’re what everyone wants to know," town spokeswoman Charlotte Reynolds said.

Authorities said there could be a variety of causes for the slide, including prior construction at the site, warmer weather and a wet winter that put more water into the ground where it acts as a lubricant for unstable rocks and soil.

Experts say the hillside is unlikely to suddenly collapse like the March 22 landslide in Oso, Wash., that killed 39 people. More likely, large blocks of earth would tumble down piece by piece.

But the threat is real and authorities are enforcing an evacuation order in hopes of avoiding injuries. Town officials first noticed significant hill movement April 4. They evacuated 42 homes and apartment units April 9.

By Saturday morning, the shifting earth had bulged a road and a parking lot at the foot of the hill by as much as 10 feet. The groundswell pushed a small town water pump building 15 feet toward West Broadway, the town’s main drag.

The ground had been moving at a rate of an inch a day but is expected to move increasingly faster as time goes on, said George Machan, a landslide specialist consulting for the town.

Rockslides are common throughout the Rocky Mountains in the spring, as melting snow and warmer weather unleashes the region’s dynamic geology. In the early 1900s, a massive slide caused by heavy rains north of Jackson formed a natural dam across a small river. The dam gave way two years later, unleashing a flood that killed six people.


story continues below
story continues below

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."

In other areas, such as around Puget Sound in Washington state, entire neighborhoods have been built upon old landslides that are no longer moving — and may or may not move again.

Still other landslides, he said, occur so slowly that highways are built over them. The highways get rebuilt, again and again, to compensate for the movement.

Next Page >


Copyright 2014 The Salt Lake Tribune. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Top Reader Comments Read All Comments Post a Comment
Click here to read all comments   Click here to post a comment


About Reader Comments


Reader comments on sltrib.com are the opinions of the writer, not The Salt Lake Tribune. We will delete comments containing obscenities, personal attacks and inappropriate or offensive remarks. Flagrant or repeat violators will be banned. If you see an objectionable comment, please alert us by clicking the arrow on the upper right side of the comment and selecting "Flag comment as inappropriate". If you've recently registered with Disqus or aren't seeing your comments immediately, you may need to verify your email address. To do so, visit disqus.com/account.
See more about comments here.
Staying Connected
Videos
Jobs
Contests and Promotions
  • Search Obituaries
  • Place an Obituary

  • Search Cars
  • Search Homes
  • Search Jobs
  • Search Marketplace
  • Search Legal Notices

  • Other Services
  • Advertise With Us
  • Subscribe to the Newspaper
  • Access your e-Edition
  • Frequently Asked Questions
  • Contact a newsroom staff member
  • Access the Trib Archives
  • Privacy Policy
  • Missing your paper? Need to place your paper on vacation hold? For this and any other subscription related needs, click here or call 801.204.6100.