Landslides: Extent and economic significance in the United States

Landslides occur in every state of the nation and its island territories (Guam, Puerto Rico, Virgin Islands, and Samoa). They have damaged or destroyed roads, railroads, pipelines, electrical and telephone transmission lines, mining facilities, petroleum wells and production facilities, houses, commercial buildings, canals, sewers, bridges, dams, reservoirs, port facilities, airports, forests, fisheries, parks, recreation areas, and farms. Much landslide damage goes undocumented because it is considered instead with its triggering event, and thus is included in reports of floods, earthquakes, volcanic eruptions, hurricanes, or coastal storms, even though damage from the landsliding may exceed all other costs. Also, overall landslide damage tends to be underestimated because so many different terms are used for the losses, such as flash flood, avalanche, clay failure, tidal wave, cliff collapse, coastal erosion, land sinking, cave-in, mudslide, road slip, hillside slip, land slip, and debris slip. Despite uncertainty in determining damage costs, landsliding in the United States is estimated to cause an annual loss of about $1.5 billion and at least 25 fatalities. California, West Virginia, Utah, Kentucky, Tennessee, Puerto Rico, Ohio, and Washington have the most severe landslide problem, based on landslide damage to roads, houses, and other buildings in the decade from 1975 to 1983. About 20,000,000 landslides have occurred in these and other states and outlying areas. Nearly all of these landslides were triggered by precipitation, earthquakes, volcanism, erosion, and the activities of humans.