GENEVA (AP) — Authorities in eastern Switzerland ordered residents of the tiny village of Brienz to evacuate by Friday evening because geology experts say a mass of 2 million cubic meters of Alpine rock looming overhead could break loose and spill down in the coming weeks.

Local leaders said during a town hall and a media event Tuesday that residents would have to leave by 6 p.m. on Friday but could return to the village from time to time starting Saturday, depending on the risk level, but not stay overnight.

The centuries-old village straddles German- and Romansch-speaking parts of the eastern Graubunden region, sitting southwest of Davos at an altitude of about 1,150 meters (about 3,800 feet). Today it has under 100 residents.

The mountain and the rocks on it have been moving since the last Ice Age, local officials say. But measurements indicated a “strong acceleration over a large area” in recent days, and “up to 2 million cubic meters of rock material will collapse or slide in the coming seven to 24 days,” officials said.

Over the last century, the village itself has moved a few centimeters (inches) each year, but the movement sped up over the last 20 years. The landslide has been moving about a meter (about three feet) per year. Geological surveys suggest the situation has become even more precarious.

Christian Gartmann, a member of the crisis management board in the town of Albula, which counts Brienz in its municipality, said experts estimate there's a 60% chance that the rock will fall in smaller chunks, which may not reach the village or the valley. The landslide could also move slowly.

But there's also a 10% chance that the whole 2-million-cubic meter mass may tumble down, threatening lives, property and the village itself, he said.

“We hope that the village stays intact,” Gartmann said by phone. “We can't eliminate the possibility that it (the rock) will come down. ... It could damage the village or destroy it."

Gartmann said glacier melt had affected the precariousness of the rocks over millennia but that melting glaciers due to “man-made” climate change in recent decades wasn't a factor.

Experts concluded that a controlled explosion to set off a rock slide was too dangerous because it would require drilling under the rock — itself a hazardous operation, Gartmann said. Erecting a giant pile of sand or a wall to try to hold back the rocks also wasn't considered feasible, he said: The wall would have to be at least 70 meters (230 feet) high to protect the village.

Many of the evacuees were expected to stay with family or friends, though local leaders have received offers from concerned neighbors to provide temporary housing. he said. At the current “orange” alert level, however, farm animals were to be left behind.

Federico Pelico, the pastor of Albula and Brienz, said they managed to disassemble and remove the precious 500-year-old winged altarpiece that was in the church.

“The church and the altar are important, but the people are more important,” he told The Associated Press in a phone interview.

Pelico said many residents of the village had grown used to hearing the regular thunder of rockfall over the years. “But now they’re suddenly realizing that something terrible might happen.”

“They have to leave their village,” he added. “These aren’t just buildings. There are emotions and histories here. I’ve seen a lot of tears lately.”

Pelico said members of his congregation are torn between hope and pain.

“There’s nothing you can do against nature,” he said. “But deep in their hearts, there’s hope that they’ll be able to return to the village.”

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Frank Jordans has contributed to this report from Berlin.