600-foot section of road quietly slips into ocean

A 600-foot section of a bluff-top roadway in San Pedro collapsed into the Pacific Ocean following heavy weekend rains, instantly carving a sheer, gaping canyon into the shoreline.

The earth and asphalt moved as a giant block, slipping away gently and swiftly about 3 p.m. Sunday, L.A. City Engineer Gary Moore said.

“This entire coast along here is a cliff,” Moore told reporters Monday, standing about 25 feet from the edge of the newly formed drop-off. “So nature has created a new cliff.”

The 100-foot-high coastal bluff on Paseo Del Mar between Western and Weymouth avenues has been moving slowly seaward for several months, but Sunday marked the first time that a sizable mass of earth slid away at one time.

None of the 15 or so contractors working at the site at the time was injured. Authorities say no structures or homes in a nearby neighborhood are at risk.

One worker who was on scene Sunday reported the slide was nearly silent, with the earth slipping away in a matter of seconds, L.A. County Department of Public Works area engineer Hector Bordas said. Before the worker could even grab his camera, it was over.

The slide transformed what was once a flat roadway into a chasm up to 75 feet deep, its bottom littered with chunks of asphalt and concrete, fallen utility poles, railings, electrical wiring and concrete pipes.

“Someone called it a mini-Grand Canyon,” said Richard Lee, a spokesman for the public works department. “I wouldn’t go that far, but it doesn’t look good.”

In a statement, Los Angeles Mayor Antonio Villaraigosa called it a “significant landslide” and urged residents and visitors to keep away from the stretch of roadway, which has been closed since September.

“The landslide area remains unstable and presents a life-threatening hazard,” he said.

Citing safety concerns, the city last week built a chain-link fence around the site and boosted police patrols to keep out trespassers, vandals and spectators.

Still, the barricades and warning signs didn’t seem to deter dozens of gawkers who gathered Monday to get a glimpse of the destruction by craning their necks along the 8-foot-high fence and peering down from a hillside high above.

U.S. Rep. Janice Hahn (D-San Pedro), a former L.A. councilwoman who lives a few blocks from the site of the slide, said she would ask the governor to consider a disaster declaration and would see if federal emergency funds could be secured.

“It’s gone, it’s gone. It’s fallen into the ocean and it’s devastating to me,” Hahn told KTLA news. “I’m very concerned about the homes that are just a few feet away and hoping that we’re going to figure out a way to stabilize this and not have it go any further.”

City engineers don’t know exactly what is causing the instability, though “rain doesn’t help,” Moore said. Whether the bluff will hold its new boundaries or continue to crumble away remains to be seen, he said.

To determine the extent of the slide and, eventually, what might have caused it, the city has hired a geotechnical consultant. In the coming weeks the firm, Shannon & Wilson, Inc. will drill 80 to 100 feet below the ground, taking soil samples and analyzing them in a lab to find the bluff’s failure points. The work will cost at least $100,000.

The city began monitoring the unstable bluff last spring when cracks opened up on the coastal roadway. The land started sinking, buckling and moving slowly toward the ocean several months ago and had accelerated in recent weeks, exposing huge crevices in the road and adjacent White Point Nature Preserve.

There’s no predicting when it might slide again, officials said.

As a precaution, the city plans to keep a close eye on the slide during the Thanksgiving holiday, when more rains are forecast.

Such a dramatic landslide isn’t without precedent on the Palos Verdes Peninsula. The coastline has long been prone to geological failure because of slippery rock formations that dip toward the sea and ocean waves that wear away at the base of coastal bluffs.

The so-called “Sunken City,” a residential area that started collapsing in 1929, is just a few miles away.

Portuguese Bend, just up the coast in Rancho Palos Verdes, has been geologically unstable since the 1950s, when construction triggered a landslide that destroyed more than 100 homes. A 1999 landslide in the area sent the 18th hole of a golf course crashing into the ocean.

tony.barboza@latimes.com