A mudslide near Thistle that has continued moving the past few days is threatening two Utah Power lines running up Spanish Fork Canyon.
Utah Geological Survey officials say the Pasture slide, located one mile north of the old Thistle slide that broke loose and blocked U.S. 6 in the spring of 1983, has swept about three poles about 30 feet down a hillside. Utah Power officials checking power lines discovered the slide east of a small lake called Shurtz Lake."Right now, the slide is still moving but has slowed," said Barry Solomon, a spokesman for Utah Geological Survey.
The slide is threatening a 138,000-volt line that carries power from a substation near Spanish Fork to a substation near Soldier Summit. Dave Eskelsen, Utah Power spokesman, said crews took measures to reduce tension in the line, but the line was still in service Tuesday afternoon.
However, a 46,000-volt line has been taken out of service near the slide. Canyon residents who get service from the line are now getting service from other lines.
"Until the slide stops and stabilizes, it doesn't make sense to do much," Eskelsen said. "We're just watching it real close as things develop."
The lines service Carbon County, areas near Scofield and other parts of the canyon. Power outages were reported in the Price area, but Eskelsen said it is unlikely that the outages are related to the slide.
"There are too many substations between this problem and Price," he said.
Because the slide is slowing, geologists don't expect any long-term impact. Crews monitoring the slide say it moved 6 feet between Thursday and Monday. One power pole dropped 2 feet during that time.
The slide is approximately 1,000 feet wide by 3,000 feet long. In comparison, the Thistle slide surface area was more than twice as large and was about 100 feet deep.
"We estimate the slide's depth at 50 feet, meaning it would contain about 6 million cubic yards of earth," Solomon said.
The Pasture slide is a prehistoric slide and geologists believe it was reactivated by exceptionally saturated soil caused by melting snowpack. Underneath the soil are layers of shale and mudstone. When these layers get wet, the slide becomes unstable and shifts.
The old Thistle slide has also moved again this spring. More than 20 percent of the slide has shifted, causing fresh cracks in the most expensive slide in U.S. history. Officials don't consider the Thistle slide a new threat.
Geologists warn that wet conditions have created a high threat of mudslides across the Wasatch Front. Many high-risk areas are being monitored during the runoff. Canyons in Davis County are among the highest risk. Solomon said the cone-shaped canyons can create fluid-like landslides of debris. The flow can easily exit the canyons and sweep away trees, boulders, or anything in the slide's path.
Big and Little Cottonwood Canyons also have a high danger of debris flow. Because there are few housing developments and the canyons are large, however, slide damage would likely be minor.