Map of Palos Verdes Peninsula, pointing out evacuation warning area in Rancho Palos Verdes. Los Angeles Almanac map.
Despite the region being identified as a hazardous landslide area as early as the 1920s, the Palos Verdes Peninsula, which had mostly been agricultural land, saw accelerated construction after World War II. The area consists of ancient landslide complexes, reported to be hundreds of thousands of years old, four of which lie underneath the city of Rancho Palos Verdes. Decades before that city’s incorporation, one of those complexes, the Portuguese Bend Landslide, was activated in 1956 by a Los Angeles County road construction crew. They were constructing an extension of Crenshaw Boulevard, south of Crest Road, and moved thousands of tons of dirt to the top of the slide complex. This shifted enormous weight to where the landslide complex hadn’t moved in 4,800 years. The slide that resulted caused the destruction of 130 of 170 homes in the area.
Since then, until recently, slides in the Rancho Palos Verdes area hadn’t been nearly as destructive, despite the land moving at a rate of about eight feet per year. The neighboring cities of Rolling Hills and Rolling Hills Estates also saw slides over the years, although equally less dramatic and destructive. However, after two historic sequential rain seasons since 2022, massive amounts of water flowed into the many ground fissures, injecting huge amounts of subsurface water below the slide complexes. This re-ignited devastating slide activity. Land movement accelerated to a rate of 9 to 12 inches per week. The famous Wayfarers Chapel – a national historic landmark built in 1951, designed by architect Lloyd Wright, son of Frank Lloyd Wright - was disassembled and stored elsewhere to save the structure. By September 2024, residents of 200 homes in the Portuguese Bend neighborhood of Rancho Palos Verdes were forced to evacuate, many of whom had lived there for decades. For safety reasons, gas and electricity utilities indefinitely cut service to 245 homes in the area. California Governor Gavin Newsom declared a state of emergency for the city.
Engineering efforts were underway in Rancho Palos Verdes to extract water from beneath the slide complexes in an attempt to slow the progress of land movement. These efforts, however, are very expensive, far exceeding the city's budget. In 2023, FEMA granted the city $23.3 million to help fund landslide mitigation efforts.
Also see: Land Movement Updates - City of Rancho Palos Verdes
and Palos Verdes Peninsula Landslides - Wikipedia
