NASA mapping shows Palos Verdes landslide movement at 4 inches per week
Researchers from NASA's Jet Propulsion Laboratory used airborne radar to measure activity of the slow-moving Palos Verdes Peninsula landslide, which showed movement by as much as 4 inches per week.
Data gathered from four weeks in the fall of 2024 showed the speed of the movement to be "more than enough to put human life and infrastructure at risk," Alexander Handwerger, JPL landslide scientist said.
The information was provided to California officials to support the state's response to the landslides. In September 2024, Gov. Gavin Newsom declared a state of emergency in Rancho Palos Verdes, as utilities were cut off, and homes evacuated due to drastic movement.
The affected area on the Palos Verdes Peninsula is part of a decades-long, slow-moving landslide, and the deluge of rainfall from storms in 2023 and 2024 significantly accelerated land movement.
Earlier this week, the City of Rancho Palos Verdes said the average movement for the entire landslide complex has decelerated by about 3% since December 2024.
The city reported that "in general, it appears that the movement rates are reaching a steady state of significantly reduced movement ...," due to the dewatering wells, and dry conditions. A total of eleven dewatering wells have been installed since Sept. 2024, serving as underground drains to extract water that contributes to land movement. This week, the council approved eight to ten new deep dewatering wells.
Through the Federal Emergency Management Agency's $42 million Voluntary Property Buyout Program, the city anticipates being able to offer buyouts for 23 damaged properties within the landslide areas. Of these buyouts, 15 are expected for red-tagged properties, and eight for yellow-tagged properties.
The city council also extended by 60 days the local emergency declarations in the landslide area, prohibiting bicycles, motorcycles, and other similar wheeled vehicles along the approximate 2-mile stretch of Palos Verdes Drive South, from the site where Wayfarers Chapel was to Schooner Drive.