If questions persist about site stability, a review by a licensed geologist or geological engineer is a reasonable next step. Your city or county planning and building department is a good place to start research on any parcel. Erosion and landslides are two different processes. Erosion is a function of several variables, including slope length and steepness, rainfall volumes and intensities, the inherent erodability of the soil, and the type of vegetative cover. A home site on silty soils at the bottom of a long, steep hill with no vegetative cover is clearly more erodable than a site with other characteristics.
Landslides are a function of the site geology and are oftentimes more difficult to predict.
Some features to look for include hummocky or uneven topography, spring lines and seeps, trees that are bent or twisted, or fence lines that are no longer straight or upright. If you find a site that you have questions about, look at the available literature on the geology of the site to see if it is in an area that is considered slide-prone. If questions persist about site stability, a review by a licensed geologist or geological engineer is a reasonable next step. Your city or county planning and building department is a good place to start research on any parcel. Some jurisdictions may also have developed hazard maps that will at least give you preliminary information concerning the potential risks associated with the property in question.