You hear it, and you know immediately what it is. Then you see all the dust, says Fernando Giovanoli, the communes deputy president. He had seen the rockfall from his mountainside home opposite the mountain. People have lived in the valley for more than 1,000 years, but recently, rockfalls have become more frequent, even fatal.
Across Switzerland, reports of rockfalls are piling up. Some have blocked streets, others have destroyed infrastructure. In the most catastrophic events, millions of cubic tons of rock have crumbled off mountains and crushed tourists. Last week in the Italian Alps, authorities closed roads and evacuated residents after warnings that a large part of the Planpincieux glacier was at risk of collapsing.
For the Swiss authorities, these increasingly common rockfalls present a major challenge. As global heating melts the myriad glaciers across the Swiss Alps and thaws its soil, related natural disasters are made more likely. Whats impossible to tell is when or where the next catastrophe will occur.
The Piz Cengalo is one example. Although experts were keeping a close eye on movement on the mountain, they could not tell how bad that rockfall in August 2017 would be. One morning, the 100-plus residents of the quaint village of Bondo heard the roar. In an instant, they had to leave their belongings and flee.
More than 3m cubic meters of rock descended from the Piz Cengalo, killing eight hikers. The sliding rocks then triggered massive mudslides that funnelled down the valley and flooded the village.
We never thought that we would be displaced for four months, that itd take so long for us to return, says Manuela Marazzi, who was ironing shirts when the mountain crumbled. Opposite her home, a car-sized rock engraved with the date of the event serves as a commemoration, one of thousands that washed down the valley that day. Two years later, electricity and water pipes are still provisional. Part of the carpentry shop, the largest employer in the tiny village, is still closed. The hikers bodies remain on the mountain.