Landslide Problems May
Continue in 1999
1998 was Worst Landslide Year
Since 1983, Survey Says

Following two years of precipitation that was well above average, the spring of 1998 produced northern Utah’s most active landslide season since the early 1980s. The Utah Geological Survey predicts that, with the relatively wet summer and fall of 1998, there will likely be continued landslide problems next spring, even with a normal winter. The UGS published a summary of the season in the latest issue of its magazine, Survey Notes.

The northern Wasatch Front was particularly hard-hit by landslides in 1998. More than $1 million worth of homes have been either condemned or destroyed in 1998 as a result of slide activity. An untold amount of damage to other real estate has occurred over the past several wet years. Many of the landslides retain the potential to produce significantly more damage in coming years. The situation is similar throughout the western United States, where coastal states and others have suffered tens to hundreds of millions of dollars in landslide damages over the past few years, particularly during 1998's El Nino wet cycle.

One of the most damaging 1998 landslides in northern Utah was in Layton, where one house was condemned and two others were damaged. One landslide in South Weber threatened to block the Davis-Weber Canal. Landslides hit other sites in South Weber, Layton, Ogden, and Salt Lake City. A home damaged by continuing landsliding in Provo was finally demolished in 1998. Over the summer, an area of slow ground movement became evident in North Salt Lake, where one house was condemned and several others severely damaged. An entire neighborhood remains at risk, making this the most damaging of the recent landslides.

Another area hard-hit by wet conditions and resulting landslides this spring was Spanish Fork Canyon, where both the Shurtz Lake and Thistle landslides reactivated. The 1997 Shurtz Lake landslide moved another 50 feet in 1998, and reactivated a large mass of prehistorical landslide debris between the 1997 landslide and the Spanish Fork River, essentially doubling the volume of material involved. Also, nearly the entire Thistle landslide, except for the old landslide "dam" across Spanish Fork Canyon, moved in late May and early June. The landslide actually increased in size at the head as an area about the size of several football fields rotated and slid downslope.

"Most of the recent movement has been on steep slopes characterized by older landslides," said the magazine’s author, Gary Christenson. "Each landslide highlights the dangers inherent in hillside development and the value in applying earth-science knowledge to avoid such disasters. It’s vital that earth scientists and engineers be involved with developers and local governments in hillside development projects."