Sep 29, 10:01 AM
Gross Ruchen rockfall turns Uri valley grey
A sudden collapse above Unterschächen sent 2,000 cubic metres of rock into the Brunnital, with dust reaching far beyond the immediate site.
Uri woke to a mountain event that did not bother with the timetable. Shortly before 4 a.m. on Monday, a rockfall came down from the north face of Gross Ruchen and sent around 2,000 cubic metres of rock into the Brunnital near Unterschächen.
The collapse happened away from the settlement area, and according to the Uri chancellery no people, buildings or infrastructure were damaged. Even the cattle that spend the summer on an alp in the area had already returned to the valley earlier. So the immediate damage was limited, which is about as good as these things get.
The broader nuisance was a thick dust cloud that settled over the valley and left traces well beyond the site of the fall. André Bissig, the mayor of Unterschächen, said after an inspection flight with a geologist that the dust reached as far as Altdorf. The helicopter pilot, he added, believed the cloud could even be felt as far as Brunnen.
By the next day, the Brunnital still looked grey and washed out. Bissig said a photograph could almost pass for a black-and-white image. Cars and window frames now need to be cleaned of dust, but no wider cleanup is planned.
The rockfall came as a surprise, Bissig said. The likely trigger is the extreme summer heat, which may have melted the ice in the subsoil. According to the geologist, the permafrost probably thawed, and with it the rock lost its binding agent. That means further rockfalls remain possible.
The authorities are advising people not to enter the area along the foot of the slope and not to climb the north face of Ruchen or the Ruchenchälen. Gross Ruchen rises to 3,137 metres, and the break-off point lies at about 2,900 metres above sea level.
Written by Sandy van Dongen sandy.vandongen@alpineweekly.com
