I have posted several items relating to the on-going landslide on Paseo del Mar in San Pedro, including Dangerous Sink Hole Appears in San Pedro .
A creeping landslide has torn huge gaps in a road and dropped concrete into the sea below as it slowly destroys an oceanside bluff.
Paseo del Mar in the San Pedro area of Palos Verdes Peninsula began to buckle during the summer, and damage has dramatically worsened recently.
The scenic route is now bisected by fissures 20 feet to 30 feet deep in places.
An underground pipe that carried away storm runoff has been left jutting out into the air while segments of the concrete pipe are washed by surf below.
No nearby homes were threatened, but city officials worried that the rainy season could increase movement of the landslide.
Crews have been rerouting storm drains and power lines while erecting an 8-foot-tall fence to keep people away from the unstable area that includes beach access paths and a section of the White Point Nature Preserve. The new fence replaces a temporary fence.
"The affected area of the landslide represents an immediate and life-threatening hazard," according to a city fact sheet.
The peninsula's scenic qualities have prompted decades of homebuilding that some experts blame for further destabilizing the historically unstable ocean bluffs.
The cliffs are made chiefly of sediment and rock formations that slope seawards. The ocean also erodes the base of the cliffs, and there have been several slow-moving landslides since the 1950s that threatened several hundred homes.
Work crews are keeping a watchful eye and taking daily measurements as the land creeps seaward. In the last week, the movement has accelerated to about half an inch per day.
Aerial view of landslide area before slippage began.
Contractors are working seven days a week, 10 hours a day, manning loaders and excavators that are carving new trenches to reroute two major storm drain pipes away from the moving earth. The project could take four more weeks, but the hope is to finish before any heavy rains, which could send storm water rushing into the area, rupture the pipe and further loosen the unstable slope.
City engineers, who have classified the slide as a coastal bluff failure, say it is far enough from a nearby neighborhood that no buildings are at risk of falling into the ocean."If this fails," said Hector Bordas, area engineer for the Los Angeles County Department of Public Works, "it means our pipe and storm drain system will also fail."
A bluff-top breaking off into the ocean wouldn't be unheard of on the south-facing side of the Palos Verdes Peninsula, where weak, slippery rock formations that dip toward the sea make the earth prone to landslides.
In 1929, a residential area two miles down the coast on Paseo Del Mar started sinking into the ocean, leaving behind a post-apocalyptic-looking bowl littered with chucks of concrete and asphalt that became known as the Sunken City. A chunk of the fenced-off parcel collapsed into the ocean in July 2010.
Starting in the 1950s, the Portuguese Bend landslide — one of the most famous in California — rearranged some 260 acres in Rancho Palos Verdes. And when the Ocean Trails Golf Course was under construction in 1999, a 16-acre section — including the 18th hole — slid dramatically into the ocean. In December 2009, a chunk of earth fell from a cliff in San Pedro less than a mile up the coast from today's landslide.
Still, talk of another slide is enough of a curiosity that it draws a steady stream of visitors.