The emergency situation in Rancho Palos Verdes is a realistic reminder that land movement is a natural occurrence, which when accelerated, according to geological science experts, can lead to damage and danger.
Scientists described Southern California as a “geologically dynamic place.”
“It’s really a tragic situation. These are residences and people’s lives that are being disrupted by what is a geologic process,” said Jonathan Godt, the coordinator for the USGS landslide hazards program. “That’s of little comfort to people who are losing homes and other things, but it is a natural process.”
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The USGS is not involved in the Rancho Palos Verdes land movement emergency, but Godt and other experts have been watching it closely.
“Everything is moving in sort of imperceptible amounts – gravity is always at work,” he said. “And when you get a series of wet winters or earthquakes shaking or other factors, it becomes noticeable and damaging.”
A map from the California Geological Survey measures deep-seated landslide susceptibility. Many of the more susceptible areas of Southern California are areas we’ve seen land movement after several days of rain this winter and the year before.
One of the communities with a similar landscape to Rancho Palos Verdes is the city of San Clemente, which is about 66 miles from the Portuguese Bend community that is now under an emergency declaration.
Homeowners have told NBC4 they have not experienced significant movement since the winter, but that land movement is something that is top of mind for them, especially looking at the situation in Rancho Palos Verdes.
“If you come right to here, there’s about a 50-foot drop,” said David Boyle, a condo owner who described the bluff just below his home. “This vegetation went all the way across.”
Boyle shared some before and after pictures which showed a big chunk of the hillside has eroded in the nine years he’s lived on West Marquita.
“Every time it rains, I wonder,” he said.
The old city hall property on Avenida Presidio has also experienced land instability, according to the city.
“You have a spectacular backdrop where you really get to see what San Clemente is all about,” Chris Duncan, city councilmember and former mayor, said as he described the view from the property. But he also explained why the city hasn’t been able to find a new owner for it.
The city put the property up for sale in 2021, during which time a geological survey found instability in the ground.
“You’ve got significant amount of dirt moved down to the parking lot area, which is indicative of the larger problem,” said Duncan. “This whole area is geologically unstable.”
