A landslide-hit California town has been at risk for decades, and the landslides may be unstoppable

Rancho Palos Verdes, a coastal community in the Los Angeles area, could be described as a ticking geological time bomb.

The wealthy city sits on steep cliffs overlooking the Pacific Ocean, which have slowly shifted and given way over the centuries.

Now this movement is accelerating. While the ground sank by 20 centimeters per year in recent years, in some places it fluctuated by 33 centimeters per week between July and August.

The resulting landslides destroyed seaside homes, blurred roads and forced utility company Southern California Edison to cut off power to nearly 250 homes to prevent possible fires.

“Two inches per year is measurable and the road that goes through the area had to be repaired, but now it's moving so fast that several roads have had to be closed, gas supplies have had to be shut off and power has had to be cut off,” said Eric Fielding, a geophysicist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. “It's crazy, but you can't put in new power lines every week.”

In the Portuguese Bend neighborhood of Rancho Palos Verdes, 140 households will be without power indefinitely, while in the Seaview neighborhood, about 60 households will be without service for a week or more.

Governor Gavin Newsom declared a state of emergency in the city on Tuesday.

The situation is the unfortunate accumulation of intense rainfall over the past two years, experts say. The Palos Verdes Peninsula is made up of weak rock and clay layers that prevent water from draining properly underground. During heavy rain or high tectonic activity, the cliffs can slide, turning constant, slow landslides into disasters.

It is not yet clear whether and what can be done to stop the earth's movement.

“Basic physics says that once a body is in motion, it wants to stay in motion,” said Jonathan Godt, landslide hazard program coordinator with the U.S. Geological Service.

The threat to Rancho Palos Verdes is not new. Scientists say the land beneath the city has been moving for hundreds of years, but was mostly stable until a road-building project in the 1950s accelerated the landslide.

“The landslide was moving even faster in the 1950s than it is today,” Fielding said, “but by drilling wells and pumping water out, it was largely stabilized.”

Now, heavy rains at the beginning of this year and last year have caused the landslide rate to accelerate again.

Fielding said it is difficult to make a direct link between landslides and climate change, but global warming is making rainfall more intense because a warmer atmosphere can hold more moisture, increasing the likelihood of severe storms.

Even knowing that heavier rains are more likely, it's difficult to predict when large landslides will occur, Godt said. After periods of heavy rainfall, it can take months or even years for water to penetrate deep rock and clay and deform the land.

It's also difficult to predict which slow-moving landslides might become problematic. Landslides that move at a snail's pace over hundreds or thousands of years are not uncommon in Southern California — and around the world, Godt said.

“For many of these places, it's not a problem over the lifetime of a person or even several generations, because from a geological perspective, it's just a blink of an eye,” he said. “But there are cases where a series of heavy rains or shaking from earthquakes or other geological processes under our feet will set these landslides in motion again.”

Rancho Palos Verdes is already facing setbacks in potential efforts to contain the earth movement. Last month, the city said it had discovered an even deeper landslide in the area that was also active. Officials said the movement, at a depth of more than 300 feet, was too fast and too deep underground to dig drains and pumps to extract water.

Now that the state of emergency has been declared, Rancho Palos Verdes Mayor John Cruikshank said the money provided would go to the city government and landslide mitigation efforts, not to individual homeowners.

Homeowners whose power has been shut off will have to raise tens of thousands of dollars or more to switch to off-grid alternatives such as solar and battery technologies, Cruikshank told a local CBS affiliate Wednesday. He hopes the state will cover those costs.

Residents are already liable for damage to their homes, Cruikshank added, because landslides, hundreds of which are recorded in California each year, are not covered by standard home insurance policies.

Tim Kelly, a mechanical engineer who moved to the Portuguese Bend neighborhood in Rancho Palos Verdes 30 years ago, said he now relies on his solar panels for power and stays in his home. He attended a public meeting Tuesday where residents asked city officials for solutions.

“We are resilient,” Kelly said of the community. “We are not going anywhere.”

Kelly said the foundations of other homes in his area had shifted, and some buildings had cracked and split in parts, but his house remained unchanged. He and his neighbors would not abandon their homes and would wait for government leaders and scientists to figure out how best to “stop” the landslide, he added.

Kelly said that for decades, local government has failed to find long-term solutions to prevent water from soaking the canyon and draining into the sea. Now the problem is coming to a head for the city, and time is running out.

“The patient is sick,” Kelly said, “and something must be done to bring him back to life.”

This article was originally published on NBCNews.com.