T150 Landslide Inventories, Hazard Assessments, and Risk Reduction

Monday, 23 September 2019
1:30 PM - 5:30 PM
Room 224A, North Building

A NEW LOOK AT AN OLD STORM: THE 50TH ANNIVERSARY OF THE LANDSLIDE DISASTER IN NELSON COUNTY, VIRGINIA ASSOCIATED WITH HURRICANE CAMILLE

Paper number: T150-7
Program: Technical Sessions
Time: 3:10 PM – 3:25 PM

Authors

  • Anne Witt Presenting Author
    Division of Geology and Mineral Resources, Charlottesville, VA

Abstract

August 19-20, 2019 will mark the 50th anniversary of one of the most tragic landslide disasters in the United States. On that summer night in 1969, portions of rural Nelson County in Central Virginia received over 30-inches of rainfall in 8-hours, triggering thousands of debris flows. Over 120 residents were killed (nearly 1% of the county population at the time), mostly by landslide impact. The Virginia Department of Mines, Minerals and Energy (DMME) is completing a new landslide hazard assessment of the area using funds provided by FEMA through the Pre-Disaster Mitigation Program. This project will be the first of its kind in Virginia to employ newly released, high-resolution 1-meter LIDAR to identify landslides and determine landslide susceptibility. One of the deliverables for the project is an updated landslide inventory for this hard-hit area of Nelson County. Earlier inventories by the U.S. Geological Survey (1999) identified up to 2000 landslides by interpreting post-storm aerial photography. However, DMME has inventoried nearly 6000 landslides from the 1969 event using LIDAR, adding important detail to this already impressive dataset. Approximately 90% of these landslides initiated on slopes between 30-50 degrees, which is unusually steep for landslide initiation in the Blue Ridge of Virginia and North Carolina. Surprisingly, the 1969 landslide locations do not correlate well with rainfall patterns from Hurricane Camille and indicate that the underlying geology may be a more significant factor in landslide initiation in this area than previously thought.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-339715

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