Geologist: Laguna Landslide Predictable
LOS ANGELES — The Laguna Beach landslide that destroyed at least 11 homes and displaced hundreds of residents last month was a predictable result of geologic conditions in the area, according to a report to be released Wednesday.
Mark Johnsson, staff geologist for the California Coastal Commission, was expected to present the findings at the commission’s meeting in San Diego. He said in an interview Tuesday that the landslide occurred because heavy rain from months earlier accumulated in the ground and reduced friction between the rock the homes were built upon and the underlying plain.
“Whenever you have steep slopes, landslides happen,” Johnsson said. “This particular place had some clues that it was a particularly unstable area.”
Other parts of Southern California have similar conditions, including parts of the Pacific Palisades, he said.
Johnsson said builders should have studied the conditions before building homes in the area, but that many were erected before modern building standards. He said many precautions would likely be needed before new development could occur, including redistributing land and building retaining walls, but that no study has been completed.
Bob Burnham, Laguna Beach’s community recovery coordinator for the landslide, said most of the homes were built in the early 1960s, though one was built in 1997.
“My understanding is that there are a lot of areas in Southern California that have conditions similar to the ones here,” he said.
The June 1 landslide destroyed at least 11 homes, with several others severely damaged or on unstable ground, Burnham said.
Burnham said some of the displaced families have rented homes near the area or elsewhere in Orange County, and that the city is trying to provide free temporary housing for three families.
The Coastal Commission will work closely with Laguna Beach to avoid any disagreements about the cleanup, Johnsson said.
Laguna Beach has authority to issue permits for building and cleaning up the region, but the commission can override cleanup permits for the region within 100 feet of a stream running through Bluebird Canyon, the site of the slide.
The stream was clogged by the landslide, and flooding could result if the city doesn’t clear a route for water to drain from the canyon, Johnsson said. The city will also need to preserve riparian habitat along the stream, he said.
Burnham said the city will clean up the area by blocking off debris, removing it, and adding a storm drain to remove water.
He said the city would need to spend about $4 million on emergency protective measures, including clearing the drainage and stabilizing a cliff. Long-term costs were unknown, Burnham said.
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