In Southern California, the growing risk of landslides has put many communities on edge, demonstrated by radar data from NASA focused on the Palos Verdes Peninsula in Los Angeles County.
The peninsula, which sits south of Los Angeles and juts out into the Pacific Ocean, contains an ancient landslide complex that has been active for the past six decades. However, exacerbated by intensifying bursts of rainfall due to climate change, the gradual movement of the landslides has drastically accelerated in recent years.
Surveying the Palos Verdes Landslides
The Advanced Rapid Imaging and Analysis (ARIA) team, featuring collaboration between NASA's Jet Propulsion Laboratory and Caltech, has been eyeing the progress of the Palos Verdes landslides, recently reporting heightened activity that occurred during the fall of 2024.
Radar imagery from ARIA revealed that during a four-week period (September 18, 2024 to October 17, 2024), land in the residential area of the peninsula slid toward the ocean by as much as 4 inches (10 centimeters) per week. The data was captured from four flights of NASA’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), a radar instrument mounted to an aircraft that flies over areas to measure Earth deformation.
The acceleration of landslides in the peninsula can be attributed to record-breaking rainfall in California in 2023 and heavy precipitation in early 2024, according to NASA.
Intense Weather Whiplash
California is especially vulnerable to rapid shifts in weather trends that climate scientists are starting to call weather whiplash.
A prime example of weather whiplash is the startling turn from dry to wet conditions that California experienced a few years back; from 2020 to 2022, the state went through a drought that marked its driest three-year period on record. Then, from late December 2022 to March 2023, severe rainfall raged across the state, leading to over $4 billion in property damage and at least 22 deaths.
Cycles of precipitation are routine in California due to the process of El Niño and La Niña, fueled by continuously changing climate patterns in the Pacific Ocean. However, the impact of extreme climatic swings has escalated with the warming of the atmosphere, causing it to hold more moisture and, in turn, amplifying precipitation.
Read More: Worsening Climate "Whiplash" Helps Explain Why California's Wildfires Were so Ferocious
The Plight of Portuguese Bend
The Palos Verdes landslides have threatened multiple communities on the peninsula, but they’re perhaps most disastrous to the city of Rancho Palos Verdes on the coast. The Ancient Altamira Landslide Complex that the city sits on takes up over two of its roughly 14 square miles. A major portion of this complex is the Portuguese Bend landslide, which has greatly disturbed the neighborhood of the same name.
The Portuguese Bend neighborhood has seen a substantial increase in landslide activity starting in 2023, as surface water from heavy rainfall percolated into the ground, adding weight to the unstable soil. The active landslide complex, according to the city of Rancho Palos Verdes, has expanded from 380 acres to 700 acres.
Fighting Back Against Landslides
The city notes that the landslide has decelerated since October 2024 due to drier weather conditions and the dewatering wells. Increased landslides are likely to return with wet weather, but the city hopes to curb them through the Portuguese Bend Landslide Remediation Project, a long-term effort planned since 2017; the project aims to remove water trapped underground and prevent rainwater from entering the ground, with objectives like infilling fissures in the earth and planting more native vegetation.
Part of the domino effect of climate change, landslides are expected to become increasingly prevalent in the coming years, not just in California, but elsewhere across the U.S. and the globe. In the U.S., the areas most likely to be affected by landslides are mountainous, like the Pacific Coast Ranges, the Rockies, and Appalachia.
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
NASA. NASA Radar Imagery Reveals Details About Los Angeles-Area Landslides
State of California. Drought
Ranchos Palos Verdes. What is the history of land movement on the Palos Verdes Peninsula?
Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine.
