California coastal community shifts 4 inches closer to the ocean each week: NASA

A coastal community in Southern California is shifting downslope -- and closer to the Pacific Ocean -- at a rapid rate, according to NASA.

The Palos Verdes Peninsula is well-known for its landslides, which have been occurring for decades. But radar imagery recently revealed that the Los Angeles County community is experiencing a slow-moving landslide -- averaging about 4 inches per week between Sept. 18 and Oct. 17, 2024, NASA's Jet Propulsion Laboratory found.

The landslide both expanded and accelerated last summer, drawing attention to a populated region that historically had not been moving, Alexander Handwerger, a landslide scientist at NASA's Jet Propulsion Laboratory, California Institute of Technology, told ABC News.

It can be credited to record-breaking rainfall in Southern California in 2023 and heavy precipitation in early 2024, according to NASA.

But the landslide has recently slowed, Handwerger said, explaining that it was moving faster before recent imagery was collected and has since slightly slowed.

Little to no infrastructure was built on the portion that was previously known to be moving, Handwerger said. But the landslide is impacting hundreds of existing buildings.

"The speed is more than enough to put human life and infrastructure at risk," Handwerger said.

Some of the peninsula is part of an ancient complex of landslides that has been moving for at least the past six decades, according to NASA. The peninsula juts into the Pacific Ocean just south of the city of Los Angeles.

Researchers compared airborne radar images taken at four different points of time to measure the motion of the landslides in three dimensions, Handwerger said.

"That gave us more of a time series of motion," Handwerger said.

The region has been a big focus for scientific research due to the prominent landslide threat. NASA’s upcoming Landslide Climate Change Experiment will use airborne radar to study how extreme wet or dry precipitation patterns influence landslides.

In addition to airborne radar, scientists have been using satellite data to monitor the motion of the landslide.

Such analyses are provided to state officials to support response efforts to the landslides.

The threat of landslides is so persistent that the City of Rancho Palos Verdes manages a website that releases monitoring data for potential activity in the region.

And last October, the Federal Emergency Management Agency and the California Governor's Office of Emergency Services unveiled a $42 million buyout program for Rancho Palos Verdes homeowners impacted by landslides.