Reducing Landslide Risk Using Airborne Lidar Scanning Data

Abstract

Geologic change tends to happen episodically, yet some natural slopes are more continuously active than many realize. Airborne lidar scan (ALS) data have made this evident around the tragic 2014 State Route (SR) 530 (Oso) landslide site in Washington State. ALS surveys since 2003 provide the opportunity to analyze landforms near the landslide site and their change through time. Changes can be dramatic, such as in 2014, but small changes may be more important for understanding risk. Intervals before and after the 2014 landslide, and comparison between similar slopes in the region, reveal important spatial and temporal variations. ALS data collection, change detection, and recognition of temporal and spatial variations can support regional landslide risk assessments, aid in risk communication, and promote better decision making to reduce risk from landslides. Had this practice been understood, implemented, and appropriately communicated prior to March 2014, the outcome of the Oso landslide could have been less tragic. This lesson is important for all levels of government, infrastructure owners, businesses, and the public.