Wash. landslide a grim reminder for Logan
A landslide in Snohomish County, Wash., killed 39 people on March 22. The slide also destroyed 50 homes in the town of Oso. The slide that occurred in Washington was a reminder to other cities across the nation, including Logan, which experienced one in 2009.
The Logan landslide occurred on July 11, 2009, killing three people along Canyon Road. The landslide was attributed to heavy rains that took place earlier in the week, making the ground soft and causing it to slide. Steve Bowman, a landslide expert at the Utah Geological Survey, said these types of landslides are common especially where bench areas and rivers meet.
“Landslides typically occur in areas that have steeper terrain and shallower slopes,” Bowman said. “They can also occur in areas that accumulate a lot of groundwater.”
Logan is not the only area in Utah where a landslide has occurred. On October 8, 2011, a similar slide occurred on State Route 14, eight miles east of Cedar City. The slide closed down the road for seven months. Vic Saunders, spokesperson for the Utah Department of Transportation, said canyon roads can be treacherous year-round, and landslides can occur at anytime.
“We have crews constantly monitoring canyon roads for any sign of geologic activity,” Saunders said. “If land starts to show signs of moving, we will close it down immediately.”
Because Logan sits along a bench area that is heavily sloped, the risk for a landslide is very high for the city. There are many homes that sit along the bench itself, putting them at risk. Mark Nielsen, public works director for Logan, said it can take a long time for a slide to be cleaned up.
“The homes that were in the 2009 slide area have been removed,” Nielsen said. “Usually it can take months or years to clean up a slide.”
For people who live along bench areas and near rivers, there are warning signs that a landslide may be imminent, Bowman said. The biggest sign is very loose soil after a rain storm. Bowman said when the ground becomes saturated after continuous rain, the soil becomes loose and the risk for a landslide increases exponentially.
“High groundwater is a main precursor to a landslide,” Bowman said. “This makes the soil loose and allows land to move freely.”
With part of U.S. Highway 89 running parallel to the Logan River, there is increased risk for flooding that can trigger a landslide. Saunders said since there is constant geological activity, UDOT has plans in place in response to a slide on any of the canyon roads.
“Once we know of a landslide, we will send crews in to evaluate the slide and begin the cleanup process,” Saunders said. “The process depends on the size of the slide and the stability of the land.”
Due to Utah’s unique geographic nature, Bowman said even though landslides usually occur along the sides of mountains, they can strike anywhere that sits on a slope and has loose soil. He said no matter where someone lives in the state of Utah, it is important to know the local risks and make a plan in case one does occur.
“Checking out the history of previous landslides in an area is a great way to be prepared,” Bowman said.
– connor.comeau@aggiemail.usu.edu
Twitter: @Connor_Comeau