The landslide occurred shortly after 6 p.m. on the evening of February 20, 2005, just below the Davis-Weber Canal, demolishing a barn and blocking State Route 60 (South Weber Drive). The purpose of my investigation was to determine the physical characteristics of the landslide and evaluate its hazard potential to aid South Weber City in assessing the risk to development at the base of the bluff from landslides and potential canal breaches.
Damaging landslide movement in 1998 occurred near the end of a period of four or more successive years of above normal precipitation, a period referred to as a precipitation period. The precipitation period began in 1995 in the northern and central Wasatch Front where mean annual precipitation for the period was about 116 percent of normal. The precipitation period began in 1993 in the southern Wasatch Front where mean annual precipitation for the period was 120 percent of normal.
The Utah Geological Survey (UGS) has been monitoring conditions at the Springhill landslide in North Salt Lake since 1998. This report summarizes and updates some of the technical information on the landslide including the current boundary based on recent UGS mapping, movement history, and ground-water levels affecting stability. The report is intended to provide the affected residents, city officials, and utility providers with information on landslide conditions through 2008 and possible trends (what might happen in the future).
The 2012 Seeley fire was a lightning-caused fire that burned 75 square miles (48,050 acres) on the Wasatch Plateau in central Utah. The fire, which started on June 26 and was contained on July 18, was approximately 15 miles northwest of Huntington and about 12 miles east of Fairview. Thunderstorm rainfall on July 7, 2012, produced fire-related debris flows and flooding, causing damage to State Route (SR) 31 and Huntington Creek in Huntington Canyon.
At approximately 5:00 a.m. on Saturday, October 8, 2011, a large landslide detached from the south side of Cedar Canyon about 8 miles east of Cedar City, Utah. The landslide quickly moved downslope, displacing part of and burying the remainder of an approximately 1200-foot-long section of Utah State Route 14 (SR-14), an important transportation link between Interstate 15 at Cedar City and U.S. Highway 89 to the east.
Significant economic losses are associated with landslides, and Utah contains numerous landslides and landslide-prone geologic units. In the early 1980s and mid-2000s, above-normal precipitation resulted in many landslides that caused millions of dollars in losses.
The Geologic Hazards Program has an ongoing long-term Global Positioning System (GPS) monitoring program to determine movement activity in several northern Utah landslides. Landslides may move so slowly that their movement is imperceptible to humans. A geologist investigating a slow-moving landslide may determine it to be dormant and stable, based on the landslide’s appearance and short-term movement monitoring.
Twelvemile Canyon, east of Mayfield, Utah, contains large, historically active damaging landslides. Widespread landsliding in 1983 resulted in road relocations, drainage of a water reservoir, and a permanent campground closure. In 1998, a landslide deposited material in a creek causing a significant increase in the creek’s sediment load.
In 2006, a locally wet spring on the heels of a statewide wet year in 2005 resulted in an active landslide season in northern Utah. Nearly all of the 2006 landslides were re-activations of pre-existing landslides, including slides that had previously moved sometime during the past decade. The following are some of the landslides UGS geologists investigated to assist local governments with their emergency response.
Record precipitation throughout much of Utah beginning in October 2004, and record snow packs, particularly in southwestern Utah, brought us an active spring landslide season in 2005. The UGS has documented over 85 landslides in 2005, and this is probably only a small percentage of the total in the state.