GEOLOGIC HAZARDS

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Recognizing and Reducing Landslide Damage on Your Property

Landslides are common in Utah. Landslide hazards are greatest near or on steep slopes or along streams. And REMEMBER – Homeowner’s insurance typically does not cover landslide damage! If you suspect imminent landslide danger, contact your local fire, police, or public works department, inform neighbors, and evacuate.

Common Landslides in Utah

Diagram of material coming from a mountain and depositing at the bottom in a fan shape.

Debris flows consist of sediment-water mixtures that flow down a streambed or hillslope, commonly depositing sediment at canyon mouths.

Diagram of a piece of a cliff that has fallen down the slope and settled.

Slides are downslope movements of soil or rock on slopes.

Diagram of a rock chunk that has fallen off a steep cliff.

Rock falls consist of rock(s) falling from a cliff or cut slope.

  • Heavy rainfall.
  • Rapid snowmelt.
  • A wet winter and spring, particularly if previous years were also wet.
  • Grading that removes material from the base, loads material at the top, or otherwise alters a slope.
  • Earthquakes.
  • Erosion or previous landsliding removing material from the base of a slope.
  • Addition of water to a slope from agricultural or landscape irrigation, roof downspouts, poor drainage, septic-tank effluent, canal leakage, or broken water or sewer lines.
  • Existing landslides.
  • Steep natural slopes, particularly in weak geologic materials.
  • Steep construction-related cut or fill slopes.
  • Areas in or at the mouths of drainages (such as canyons).
  • Slopes below leaking canals or ponds.
  • Developed hillsides where septic-tank soil-absorption systems are used and landscapes are irrigated.
  • Below cliffs or hills with outcrops of fractured rock.

Springs, seeps, or saturated ground in previously dry areas.

Crack in the ground that is a few inches wide.

Ground crack.

Cracks in snow, ice, soil, or rock.

Soil pulling away from foundations.

Offset fence lines.

Cracking and tilted sidewalk in front of a house.

Damaged sidewalk.

Unusual bulges or elevation changes in the ground, pavements, or sidewalks.

Cracks and splitting in the cement foundation of a house with wooden supports.

Foundation damage.

Excessive tilting or cracking of concrete floors and foundations.

Broken water lines and other underground utilities.

Rapid increase or decrease in stream water levels, possibly accompanied by increased turbidity (soil content).

Decks and patios tilting and/or moving relative to the main house.

Tilting telephone poles, trees, retaining walls, or fences.

Bent doorframe with a door that doesn't fit.

Door frame out of plumb.

Sticking doors and windows, and visible open spaces indicating walls and frames out of plumb.

Appearance of bare spots on slopes.

Intermittent creaking, snapping, or popping noises from a house.

Sunken or downdropped roads.

  • Minimize landscape irrigation – overwatering on bluff-tops is a common cause of landslides.
  • Drain water from surface runoff, downspouts, and driveways well away from unstable slopes and landslides.
  • Make sure water and sewer lines do not leak.
  • Avoid removing material from the base of slopes or adding weight at the top.
  • Contact a geotechnical consultant for professional advice.

Additional Information

For further information on landslides in your area:

  • In Salt Lake County, contact the County Geologist at 468-2061.
  • Contact the Utah Geological Survey at 801-537-3300.
  • Contact Emergency Services and Homeland Security (previously Comprehensive Emergency Management) at 801-538-3400.
  • For a detailed site analysis, contact a private consulting company specializing in earth movement. Such companies are listed in the Yellow Pages and specialize in geotechnical engineering and engineering geology. Your state or county geologist could advise you of the type of professional to contact.

References

Crudden, D.M., and Varnes, D.J., 1996, Landslide types and processes, in Turner, A.K., and Schuster,R.L., Landslides, investigation and mitigation: Washington, D.C., National Research Council, Transportation Research Board, Special Report 247, p. 36-75.

Harty, K.H., 1991, Landslide map of Utah: Utah Geological and Mineral Survey Map 133, 1:500,000, 28 p.

National Landslide Information Center, U.S. Geological Survey, Denver, Colorado

Shelton, D.C., and Prouty, Dick, 1979, Nature’s building codes, geology and construction in Colorado: Colorado Geological Survey Special Publication 12, 72 p.

Zaruba, Q., and Mencl, V., 1969, Landslides and their control: Amsterdam, Elsevier, 205 p.