Geological Evaluation of West Virginia Landslides

Abstract

The major urban areas of West Virginia have been mapped for landslides at a scale of 1:24,000 under an Appalachian Regional Commission (ARC) grant. The mapping covered 36 quadrangles where recent landslides, old landslides, rockfalls, and slide-prone areas were identified. With a landslide density of 18 per square mile covering on average 11 acres each, consideration of several geological factors that are understandable to decisionmakers and the general public was warranted. From this database, a random selection of 2,416 landslides were analyzed using 12 geological map factors to ascertain the conditions associated with past failures and attempt to assess future risk. Three natural factors associated with the sampled landslides appear to be critical for the evaluation of future risks: rock formation, soil series, and slope percent. These factors, when normalized for their actual areal distribution, provide an inexpensive, preliminary assessment of the hazard prior to any financial investment or development decision. For example, if an area has one high-risk factor, building regulations may be required to meet certain additional requirements. As the number of high-risk factors increase, perhaps with consideration given to moderate or low-risk factors, these requirements would change accordingly. Examples of landslides and this normalization procedure for several areas in West Virginia are discussed. Landslide reduction techniques will also be presented.