Officials say 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.”

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. Locals say the mountain and the rocks on it have been moving since the last Ice Age, local officials say.

Over the last century, the village itself has moved a few centimeters (inches) each year — but the movement has accelerated over the last 20 years, and the landslide has now been moving about one meter (about 3 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, says experts estimate there’s a 60% chance that the rock will fall in smaller chunks, which may not even reach the village or the valley. It 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,” he 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 that glacier melt had affected the precariousness of the rocks over millennia, but that glacier melt due to “man-made” climate change in recent decades wasn’t a factor.

Experts deemed that a controlled explosion to set off a rock slide was too dangerous, because that would require drilling underneath the rock — itself a hazardous operation, Gartmann said. Erecting a giant pile of sand or a wall to try to block any spillage wasn’t considered feasible, he said: The wall would have to be at least 70 meters high to protect the village.

Many of the evacuees are 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 are to be left behind.

“The livestock from two farms will remain in the stables for the time being,” the Albula region said in a statement.