On March 22, 2014, four miles east of Oso, Wash., a portion of an unstable hill collapsed, sending mud and debris across the North Fork of the Stillaguamish River, covering an area of approximately one square mile and devastating a rural neighborhood, killing 43 people. It also dammed the river, causing extensive flooding upstream and blocking State Route 530. Excluding landslides caused by volcanic eruptions, earthquakes or dam collapses, the Oso slide was the deadliest single landslide event in U.S. history.
LiDAR data—if collected, analyzed and disseminated to local residents and policy makers—can be invaluable in mapping landslide hazards. In turn, such mapping can greatly help mitigate the consequences of landslides. After the Oso disaster, interest in landslide hazards grew significantly in Washington as well as Oregon, California and other mountainous states.