SAN CLEMENTE, CALIFORNIA -- A landslide in Southern California has closed a historic cultural centre, shut down rail service in the area and forced the evacuation of nearby residences, officials said.

The slope below the ocean-view terrace at Casa Romantica and Cultural Center and Gardens in San Clemente dropped about 20 feet (about 6 metres) on Thursday after several days of minor earth movement, city officials said in a news release. Casa Romantica announced that it was temporarily closed and all events were cancelled.

Four residential units in an adjacent building were initially red-tagged as unsafe and then overnight all 24 units were evacuated because the hillside continued to move, said Mayor Chris Duncan. Six of the units are residential and the rest are vacation rentals, he said.

Falling debris halted rail service on shoreline tracks at the base of the cliff that are used by Metrolink and Amtrak's Pacific Surfliner, officials said.

Train service was only recently restored after months of stabilizing repairs along a stretch of track in south San Clemente. The tracks were shifting due to storm surge and sand erosion on the ocean side and a gradually sliding hillside on the other, according to the Orange County Transportation Authority.

Set on 2 1/2 acres (1 hectare) atop a bluff overlooking the Pacific Ocean, Casa Romantica was originally the expansive home of the city's founder. Built in the Spanish Colonial Revival style in the late 1920s, it eventually became a cultural centre in the 1980s.

Duncan said the cause of the slide has yet to be determined, but another local official noted it follows a winter of extreme rainfall.

"We've had so much rain, unprecedented amounts of rain in the last several months, that these hillsides are very unstable," Katrina Foley, a member of the Orange County Board of Supervisors, told KABC-TV.

Cracking appeared in the terrace at Casa Romantica on April 16, and the City Council approved spending US$75,000 for experts to define the geologic conditions and determine if an ancient landslide is there, the Orange County Register reported. Crews were drilling to install equipment to measure movement Thursday when the earth began moving, Councilmember Kevin Knoblock told the newspaper.

About a half-mile up the coast, residents of three clifftop apartment buildings and one nearby building in San Clemente fled their homes in mid-March when the land began to shift and slide away from their backyards. Use of three of the buildings, with some restrictions, was allowed to resume several weeks later.

"This is unfortunately becoming recurring for us," Duncan said.

More than a dozen atmospheric rivers hit California this past winter, causing widespread damage. The threat of flooding continues as the massive mountain snowpack left by the storms begins to melt.