The systematic evaluation of landslide incidence and susceptibility in the United States

Abstract

A landslide overview map of the United States published in 1976, at a scale of 1∶7,500,000, shows areas of landslides and areas susceptible to future landsliding. The map was prepared by classifying geologic units shown on the geologic map of the United States according to high, medium, or low incidence of landslides and susceptibility to landsliding. The compilation showed that landsliding was most prevalent in fine-grained clastic rocks, particularly where they are interbedded with more resistant rocks; in highly sheared rocks, particularly melanges; and in loose slope accumulations of fine-grained surface debris. The influence of climate, structure, and lithology on landsliding in various parts of the country could not be shown on the map. These factors are compared for the Colorado Plateau in the western United States and the Appalachian Highlands in the eastern United States.