A Geographic Information System Approach to Documenting Landslides in Utah

We used a Geographic Information System (GIS) to compile more than 15,000 landslides in Utah, covering over 5% of the state. The resulting product, which includes 47 1:100,000-scale maps and an accompanying geodatabase, may be used to assist local jurisdictions in creating land-use ordinances and identifying areas where landslide hazards likely exist. Identifying landslide-prone areas is increasingly important as development continues to expand into the mountainous regions of Utah.

The maps display landslide deposits and scarps, from existing mapping, throughout Utah. Landslide deposits have been divided into several categories based on depth to surface of rupture and failure type. Shallow landslides are classified as those with a depth to the surface of rupture less than 10 feet (3 m) and include mainly debris slides and debris flows. Deep-seated landslides are classified as those with a depth to the surface of rupture generally greater than 10 feet (3 m) and include slumps, earth flows, and complex landslides. Lateral spreads and landslides undifferentiated from other mass-movement deposits (such as talus and colluvium as well as glacial deposits) are also included.

The accompanying geodatabase stores and organizes specific information about each landslide, including original data source, landslide category, historical landslide events, and likely affected and underlying geologic unit(s). The geodatabase provides information on where historical landslides have occurred, what geologic units are prone to landsliding, and the extent of landsliding in specific regions.

Significant economic losses are associated with landslides, and Utah contains numerous landslides and landslide-prone geologic units. Understanding landsliding in Utah is becoming more important as development in landslide-prone geologic units increases. Using a GIS provides an effective way to compile landslide data that may be used for future studies and planning.