Landslide Hazard Mapping on a Shoestring

Low out-of-pocket cost preparation of a landslide susceptibility map is described for the Rapid City East quadrangle, South Dakota. The map classifies all terrain from Class 1 — very low probability of landslide, to Class 6 — very high probability of landslides by an interpretation of geologic, slope, and landslide information. Each information area is prepared as a map. The geologic map was prepublished. The slope map is hand-prepared from a topographic map. The landslides are identified using borrowed air photos, marked on photo-covering acetate, and transferred to a topographic map. Maps are then combined by overlaying and the susceptibility class determined by proportion of landslide area for each slope-geologic unit.