Increased Monitoring Urged

Even as officials promised to allow residents to return to La Conchita, experts described the seaside town Wednesday as one of the most landslide-prone places in California -- so dangerous that Ventura County officials should do much more to monitor slides and warn residents of hillside movement.

“It’s one of the landslide capitals in California,” said Ed Keller, a geology professor at UC Santa Barbara. “You drive along that coast and it’s just one landslide after another.”

A string of geologists who have studied the area -- among the most scrutinized hillsides in California -- have concluded that La Conchita “is not a safe place to live,” said Howard Wilshire, a former research geologist who prepared a 1996 report on the area for the U.S. Geological Survey.

More than a dozen slides have occurred on the slopes above La Conchita since it was settled in 1850, geologists say -- two in the last decade.

The Rincon coast, which twists for 15 miles from Ventura to Carpinteria, rises at a geologically torrid pace of 5 yards every thousand years, while faults allow for rapid erosion by rainfall. The result is a series of ravines with steep sides that easily collapse when saturated by rains, according to geological reports.

“It was predictable,” said Keller. “Not the day or the hour, but the whole [Rincon] area is one of the most rapidly uplifting areas in the world.”

When drenched by heavy rains, the soil can become a muddy slough -- as on Monday, when a saucer-shaped chunk of hillside skidded down and rippled like a wave into the streets of La Conchita.

The county should not let people get in front of that kind of inevitable geological event, Keller said.

“La Conchita should be a park or something, because these slides are just going to continue,” he said.

At the very least, the county should enact new safety measures, including more extensive monitoring to warn of the slightest shiver, and an evacuation plan similar to those used for wildfires, Keller and other experts said.

“Just like with red-flag days, people should be prohibited from staying once it becomes clear the hillside is saturated,” Keller said.

Modern land-use planners would never have allowed homes to be built there, Wilshire said.

“Had consideration been given to geologic hazards, La Conchita would never have been developed,” Wilshire said. “If homeowners demand their property right to live there, then it’s their risk and it’s foolhardy.”

La Conchita was subdivided in 1924, decades before government began to shape the development of communities.

County officials said they cannot legally force residents off their property, but they can direct people to evacuate, as they did Monday night after the slide. Even so, 18 chose to stay.

After a 1995 slide destroyed nine houses, Ventura County installed monitors to detect whether the earth was continuing to slip. But officials said Monday’s slide occurred outside the monitored zone. Even after the slide, officials said, the monitors showed no movement, despite their proximity to the disaster.

Videotape showing the earth rolling down in waves indicates Monday’s collapse was probably a “flow” slide, in which super-saturated earth bursts down a mountain with tremendous force and speed, Keller said.

“It behaved as if it were a liquid,” Keller said.

Wilshire said he’s convinced Monday’s landslide occurred because of record-setting rains, not because of irrigation on hundreds of acres of orchards on the bluff above the community, as residents claimed in lawsuits against a rancher after the 1995 slide.

“Geologic records show many landslides long before they had irrigation up there on the bluff in the ‘70s,” he said.

Jeffrey Hemphill, a UC Santa Barbara doctoral student in geography, has studied La Conchita landslides dating back through written records to 1865 and photographic images to the beginning of home construction at the cliff’s base in the 1920s.

Years of satellite images show an indentation in the slope above La Conchita where repeated slides open a rift that is deeply scored by runoff. Over time, multiple slides widen the drainage into what looks like the birth of a canyon. But the slides did not reach the streets of La Conchita until the massive 1995 event.

In 1865, a surveyor assessing the potential for a wagon trail linking Ventura and Santa Barbara wrote about “masses of earth” falling from the cliffs. The surveyor concluded that “the road for the transportation of goods was nearly worthless.”

The landslides kept coming after Southern Pacific laid track in 1887, forcing the railroad to send workers to clear the tracks. After a particularly bad slide in 1909 killed four people and buried rail cars, the railroad bulldozed flat the mudflow debris at the base of the hill and cleared space as a catch basin for future slides, Hemphill’s research shows. That opened the way for development, which arrived in 1924 with the La Conchita del Mar subdivision.

Initially an agricultural town and weekend retreat, it grew into a funky community populated by permanent residents.

“The whole area was kind of built to slide,” Hemphill said. “Throughout the hillside there are sand [layers], and when you get real intense rainfall, all that water goes into the soil really fast. It goes through particles of soil and hits the sand, and then it just boogies.”