Widespread landslides across southern Appalachia following Hurricane Helene: emergency response, initial observations, and historical context

Between the 23rd–27th of September 2024, antecedent rain followed by Hurricane Helene produced widespread flooding and landsliding across southern Appalachia, resulting in one of the most damaging weather events in the region’s history. The back-to-back storms produced observed rainfall accumulations of up to 848 mm and hurricane-force winds gusting over 200 kilometers per hour in western North Carolina, eastern Tennessee, and southwestern Virginia. The resulting regional flooding, landslides, and tree blowdown caused over 100 fatalities, damaged or destroyed critical infrastructure and thousands of structures, and severed connectivity across the region. Together with state, federal, and local partners, the U.S. Geological Survey activated their landslide emergency response team to coordinate rapid remote, aerial, and field mapping of landslides and impacts, hazard modeling and assessments, daily situational reports, and development of educational and outreach materials. These efforts provided timely information to aid emergency response, and initial observations highlight strong aspect and topographic controls as well as the importance of total rainfall accumulation on landslide initiation. Subsequent post-event investigations suggest that further research is needed to understand spatial clustering of landslide initiation, controls on landslide and debris flow runout, discrepancies between preliminary mapping and hazard models, and how to more effectively inform at-risk populations about potential landslide impacts.

Mirus and Schaefer (2025) Widespread landslides across southern Appalachia following Hurricane Helene: emergency response, initial observations, and historical context, USGS Landslide Hazards Seminar, 23April 2025.