Landslides prompt state emergency declaration in Southern California

California declared a state of emergency in the coastal city of Rancho Palos Verdes on Tuesday, following severe landslides that have caused significant damage to multimillion-dollar homes.

Rancho Palos Verdes, located approximately 30 miles southwest of downtown Los Angeles, is situated on a hilly peninsula extending into the Pacific Ocean. Typically, the ground in this area shifts about one inch per year. However, recent heavy rains have accelerated this movement to up to four feet per month in some locations, according to officials.

For some homeowners in the city, where the median list price is around $2 million, these landslides have been devastating, tearing homes apart at their foundations and rendering them irreparable.

Benjamin Byers, a vice president at California-based geotechnical firm Soil Engineering Construction, explained that water from heavy rains seeped into a sandy layer beneath the surface. This created a lubricated face, allowing the material above to slide downhill due to gravity. "The super rainy winters are definitely one of the big reasons for all this," Byers told Realtor.com®. "They saturated the land, and it takes a lot of hits to get everything moving in the right way."

California receives about 75% of its total precipitation from November through March, with half arriving between December and February alone, according to the state's Environmental Protection Agency. After several years of severe droughts, California has experienced prolific rains over the past two winters. The most recent two "water years" have been among the wettest back-to-back seasons in Los Angeles since 1888–90.

Since October 2022, downtown Los Angeles has received 53.22 inches of rain—nearly matching the two-year record set in the late 1880s. This past February was one of Los Angeles' wettest months on record with over 12 inches of rain.

Byers noted that there is often a delayed effect between heavy rains and landslides: "It takes time for it to permeate all the way through."

A section of Dauntless and Exultant Drive remains closed due to ongoing landslide activity and repair work in Rancho Palos Verdes' Portuguese Bend neighborhood as of June 21, 2024. According to residents, two homes in this area have been red-tagged.

Homeowners and prospective buyers should first assess whether their property is located in an area prone to landslides by consulting maps published by both state and U.S. Geological Surveys documenting known risk areas.

Early signs of deep-seated landslides include new soil cracks, structural shifts causing doors or windows not to close properly, tilting trees, and sudden ground holes or bare spots.

Byers stated that preventive measures depend on how deep a landslide runs beneath the surface: "If it's a 50-foot-deep landslide, there's nothing you can do." However, for slides running from zero to twenty feet deep solutions are available at reasonable costs; anything beyond that may require government funding.

Simple preventive measures include planting trees whose roots help bind soil together. More advanced solutions involve retaining walls or systems controlling runoff which usually require professional assistance from geotechnical engineers.

In Rancho Palos Verdes some homes have been effectively demolished by landslides leaving owners with tough decisions about rebuilding while others still standing but under threat must decide whether they will remain.

The severity has led some questioning if abandoning affected areas entirely might be necessary though Byers believes shallow enough slides could be remediated effectively preserving property values despite lacking aesthetic upgrades like new countertops saying “But it does preserve your property values.”