Rockfall on Gross Ruchen sends dust cloud across valley

A rockfall on the north face of Gross Ruchen sent about 2,000 cubic metres of rock into a valley early Monday, creating a huge dust cloud, Swiss broadcaster SRF reported. No people, buildings or infrastructure were damaged, according to the Uri cantonal administration.

The rockfall happened shortly before 4 a.m. in Brunnital, a side valley of Schächental near Unterschächen. The fall was away from inhabited areas. Livestock that had spent the summer on an alpine pasture nearby had already returned to the valley.

Dust spread well beyond the affected area and was still visible the following day. Unterschächen mayor André Bissig said it reached Altdorf; a helicopter pilot who accompanied him and a geologist on an inspection flight said it had been felt as far as Brunnen. Bissig said the landscape looked as though a black-and-white filter had been applied to photographs. Cars and window frames will need to be cleaned, but no further cleaning measures are planned.

The rockfall came unexpectedly. A geologist cited by Bissig believes the summer heat may have melted ice in the ground and thawed the permafrost, removing what he described as the “glue” holding the rock together. Further rockfalls are possible.

Authorities strongly advise people not to enter the area along the foot of the slope or to climb the north face of Gross Ruchen or Ruchenchälen. Gross Ruchen is 3,137 metres high, and the rockfall began at about 2,900 metres.