NASA radar imagery highlights expanding landslide activity in Los Angeles

Scientists at NASA's Jet Propulsion Laboratory (JPL) in Southern California utilized airborne radar data to examine the gradual movement of the Palos Verdes Peninsula landslides. Their study found that between September 18 and October 17, 2024, portions of the land in the residential area moved toward the ocean at rates of up to 4 inches (10 centimeters) per week.

Situated south of Los Angeles, the Palos Verdes Peninsula has been affected by slow-moving landslides for over six decades, impacting numerous residential and commercial properties. These movements accelerated and extended in scope following extreme rainfall events in Southern California during 2023 and early 2024.

To assess the situation, the Advanced Rapid Imaging and Analysis (ARIA) team processed data from four flights conducted using NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR). The radar instrument, mounted on a Gulfstream III jet based at NASA's Armstrong Flight Research Center in Edwards, California, provided critical insights into both the velocity and direction of land displacement.

Color-coded imagery from the flights illustrated the shifting terrain, with darker red hues signifying the fastest-moving sections of the landslide. Overlaid arrows depicted the horizontal movement, while white boundary lines marked the limits of the landslide as delineated by the California Geological Survey in 2007.

"The expansion of the affected area and the increased speed of movement pose significant risks to both human life and local infrastructure," said Alexander Handwerger, a landslide specialist at JPL who conducted the analysis.

In addition to UAVSAR data, the ARIA team incorporated satellite imagery from the European Space Agency's Copernicus Sentinel-1A/B satellites. This comprehensive analysis has been shared with California authorities to aid in their response and is publicly accessible via NASA's Disaster Mapping Portal.

Handwerger also leads NASA's upcoming Landslide Climate Change Experiment, an initiative designed to examine how extreme weather patterns influence landslide activity. The study will use airborne radar to investigate coastal slopes across California, furthering understanding of the impact of climate fluctuations on geologic instability.