Open–File Report 2009–1155
Generally, every several years, heavy amounts of rainfall trigger a large number of debris flows within the central and southern Appalachian Mountains of the Eastern United States. These types of landslides damage buildings, disrupt infrastructure, and occasionally injure and kill people. One of the first large debris flows was described in Pennsylvania in August 1779. The most destructive event occurred during August 19–20, 1969, in Nelson County, Va. During a period of 8 hours, 710 to 800 milimeters of rain triggered more than 3,000 landslides, killing more than 150 people. As the population increases in this region, future storms will likely increase the risks of property damage and loss of life. We provide a general overview of debris flows in the Appalachians, using a compilation of 19 storm events for which rainfall, duration of the storm, and descriptions of the resulting landslides have been substantially documented.
Posted August 2009
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Wieczorek, G.F., Eaton, L.S., Morgan, B.A., Wooten, R.M., and Morrissey, M., 2009, An examination of selected historical rainfall-induced debris-flow events within the central and southern Appalachian Mountains of the Eastern United States: U.S. Geological Survey Open-File Report 2009–1155, 25 p., available only online at http://pubs.usgs.gov/of/2009/1155.