2009 Conditions:
Landslide Movement
Precipitation
Ground-Water Levels

Future Movement
UGS Monitoring
Landscape Watering

2009 UGS Activities
UGS Contact
UGS Technical Reports

Prior to 2009:
Landslide Movement
Change in Movement Rate
Ground-Water Levels

Background/Location Map
Landslide Description/Map

The Utah Geological Survey (UGS) has been monitoring conditions at the Springhill landslide in North Salt Lake, Davis County since 1998.

These web pages are intended to provide relatively frequent updates on landslide conditions, including movement amounts, changes in the rate of movement, ground-water levels that affect stability, and UGS activities.

The data presented here are provisional and subject to review and revision.

Summary of Landslide Movement and Conditions in the First Half of 2009

This section summarizes landslide conditions in the first half of 2009, specifically from January 1 through June 30, 2009. Precipitation for the current water year used by the Utah Geological Survey to track landslide potential, which began on September 1, 2008, is also discussed.

Landslide Movement in 2009

The Springhill landslide moved continuously in the first half of 2009, but the rate of movement (the speed at which the landslide is moving) was not constant. In general, the rate of movement increased from January through most of April, reaching a peak rate (fastest speed) of about 2 inches per week in the uppermost part of the landslide between April 15 and April 23. Subsequently, the rate of movement has decreased. A wet June did not cause the rate of movement to increase (in June), but reduced the rate at which the speed of the landslide had been slowing since reaching its maximum rate in April.

Total measured ground deformation (the amount that the ground stretches or shortens as landslide movement occurs) in the first half of 2009 ranged from about 8 to 11 inches across the main scarp (uppermost part of the slide) and was about 9 inches across the toe (lowermost part of the slide). The results of movement monitoring using a survey-grade GPS instrument indicated between about 6 to 9 inches of movement between January 14 and June 18. The table below summarizes the total measured ground deformation and movement in the first half of 2009.

Summary of landslide movement and ground deformation measurements, January - June 2009

Map showing results of movement monitoring of the Springhill landslide on June 18, 2009, using a survey-grade Global Positioning System (GPS) instrument. Movement directions (yellow arrows), amounts in inches (yellow text), and station numbers (white text) are shown. Movement during the measurement period ranged from about 6.2 to 8.9 inches. The landslide is generally moving to the northwest. No movement was detected directly downslope (station sh12) of the landslide, but some minor movement was detected upslope (station sh09) of the slide. In addition, some movement was detected at several stations along the edges of the landslide, outside the approximate 2008 boundary (dashed line), which we infer is the result of the landslide pushing on rigid elements (such as concrete slabs, foundation walls, etc).
Figure updated on July 7, 2009. Provisional data. Subject to revision.
Click here for larger image.

Cumulative shortening across lot 157 Valley View Drive in 2009.   Total shortening (due to landslide movement) by June 18 (date of last measurement) is about 9.1 inches. 
Figure updated on July 7, 2009. Provisional data. Subject to revision.

Cumulative stretching across the main scarp zone of the Springhill landslide in 2009.  Total stretching (due to landslide movement) between February 25 and June 18 (date of last measurement) is about 10.9 inches.  The rate of movement increased between March 11 and April 23, reaching a maximum rate of movement of 2 inches per week by late April.  Subsequently, the rate of movement decreased, reaching a low of about a fifth of an inch per week by early June.  Measurement stations are across the southeastern (uppermost) boundary of the landslide. 
Figure updated onJuly 7, 2009. Provisional data. Subject to revision.

Precipitation in 2009 and the Current Landslide Water Year

Precipitation at the landslide is estimated using data from the nearby Bountiful Val Verda National Weather Service station, a short distance north of the landslide. Precipitation in the first six months of 2009 and the current water year used by the UGS to monitor landslide potential (September through August) was above normal. In the first half of 2009, precipitation was 135 percent of normal and excess precipitation (the amount above normal) totaled about 4.6 inches. In the current landslide water year, precipitation is 125 percent of normal and excess precipitation totaled about 5.1 inches. In comparison, precipitation in the first six months of 2008 was only about 74 percent of normal, and at the end of June 2008, precipitation in the landslide water year was slightly below normal.

Ground-Water Levels in 2009

Rising ground-water levels can cause the rate of movement of a landslide to increase. Ground-water levels fluctuated in response to precipitation in 2009. Melting of the snowpack that covered the landslide in late winter caused the ground-water levels to begin rising sometime in March, depending on location. The seasonal peak levels (generally, the highest levels of the calendar year) were reached by mid-April. The fastest rate of movement occurred shortly after the peak levels were reached. The ground-water levels generally fell through May, but wet weather in June caused the ground-water levels to rise again. By late June, the levels had mostly begun to fall.

Ground-water-level changes in observation well P-1 in 2009. In late winter, the ground-water level declined during a period where snow covered the landslide. Snowmelt caused the ground-water level to rise to a seasonal peak level, during which time the rate of movement of the landslide accelerated, reaching a maximum rate of movement of about 2 inches per week within a week of the peak ground-water level. A sudden, but short-duration decline in the ground-water level of about 20 inches followed, possibly due to increased fracturing of the landslide mass as the rate of movement increased. For most of the remaining period, the ground-water level increased, possibly due to local lawn watering in the Springhill Circle area. A wet June appears to have increased the rate that the ground-water-level rose and the highest level in the first half of 2009 was reached around June 15.
Figure updated on July 7, 2009. Provisional data. Subject to revision.

Ground-water-level changes in observation well P-4 in 2009. In late winter, the ground-water level declined during a period where snow covered the landslide. Snowmelt caused the ground-water level to rise to a seasonal peak level, during which time the rate of movement of the landslide accelerated, reaching a maximum rate of movement of about 2 inches per week within a week of the peak ground-water level. The seasonal peak ground-water level in 2009 was less than 6 inches below the previous highest ground-water level recorded in April 2006. Subsequently, the ground-water level gradually declined, falling about 1 foot by June 1, before wet weather in June caused a minor rise in the level. Despite a decline in the level in late June, the ground-water level on June 29 was only a foot below the seasonal peak ground-water level in April 2009.
Figure updated on July 7, 2009. Provisional data. Subject to revision.

Ground-water-level changes in observation well P-5 in 2009. In late winter, the ground-water level declined during a period where snow covered the landslide. Snowmelt caused the ground-water level to rise to a seasonal peak level, during which time the rate of movement of the landslide accelerated, reaching a maximum rate of movement of about 2 inches per week within a week of the peak ground-water level. Subsequently, the ground-water level gradually declined, falling about 11 inches by June 1, before wet weather in June caused the level to rise over 4 inches. Despite a decline in the level in late June, the ground-water level on June 29 was only a foot below the highest level recorded in April 2009.
Figure updated on July 7, 2009. Provisional data. Subject to revision.

Future Landslide Movement

Based on above-normal precipitation, relatively high ground-water levels, and continuing movement in the early summer, the UGS anticipates that the landslide will continue to move in the remainder of 2009, and total movement will likely exceed a foot. In the future, the total annual movement amount may gradually increase, likely exceeding a foot or more each year. However, during extremely dry years, such as 2007, movement may slow or even suspend, and a prolonged dry period, such as a multi-year drought, may cause the landslide to become dormant (no movement for over a year). However, because of the uncertainty in predicting the weather in future years, residents should prepare for future movement of the landslide in upcoming years, particularly given that damaging movement occurred in 2008, a year with near normal precipitation.

UGS Monitoring of the Landslide

In the hot dry summer period, the UGS will monitor landslide conditions less frequently, due to the anticipated very slow movement during this period. The UGS will likely begin more frequent monitoring in the fall, particularly if wet weather returns.

Summertime Landscape Watering

Residents should be aware that excessive summertime landscape watering may cause ground-water levels to rise, which may cause an increase in the rate of movement. The observed rise in ground-water level in late April and May in observation well P-1 in Springhill Circle may have been caused, at least in part, by local lawn watering. The temporary rise in ground-water level caused by landscape watering interrupts the natural decline that generally occurs in the summer and early fall, leaving the level higher at the end of the year than it would have been without landscape watering. This results in a higher ground-water level in the following year, and thus, less snowpack is needed to cause a similar rise in ground-water levels as in the previous year, increasing the likelihood of future damaging movement.

For Additional Information

Contact either Francis Ashland, 801-537-3380, email: francisashland@utah.gov or Ashley Elliott, 801-537-3379, email: ashleyelliott@utah.gov.

UGS Technical Reports

Ashland, F.X., and Elliott, A.H., 2009, Update on conditions through 2008 at the Springhill landslide, North Salt Lake, Utah: Utah Geological Survey Technical Report 09-01, 19 p.

Ashland, F.X., 2003, Characteristics, causes, and implications of the 1998 Wasatch Front landslides: Utah Geological Survey Special Study 105, 49 p. see pages 20-24 for information on the Springhill landslide.

Giraud, R.E., 1999, Reconnaissance of building distress and ground movement in the Springhill Circle area, North Salt Lake, Davis County, Utah, in McDonald, G.N., compiler, Technical reports for 1998, Applied Geology Program: Utah Geological Survey Report of Investigation 242, p. 60-75.