A violent thunderstorm in the area caused instable rock to detach from the Piz Cengalo mountain, sparking a wave of mud, rock and debris to flow towards Bondo in a near-repeat of the events of August 23rd when three million cubic metres of rock detached from the same mountainside.
Police spokesman Roman Rüegg told news agency ATS that the size of the latest landslide could not yet be measured, but it was significant.
The authorities had feared another, saying that a further 500,000 to one million cubic metres of rock remained prone to fall and could be destabilized by the bad weather.
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The latest landslip once again filled Bondo's rockfall retention reservoir, which had been partially emptied after it was overwhelmed by the first landslide, said the Bregaglia commune in a statement.
Streets that were spared during the first landslide were hit this time. The mass of sludge also covered the riverbed and two access roads, cutting off the village.
No one was in Bondo at the time, since the village had remained evacuated following the first rockfall last week. However residents and hotel guests in the neighbouring village of Spino were evacuated and two elderly people had to be rescued by Rega helicopter.
Houses in Spino and the villages of Promontogno and Sotoponte were damaged, with some completely destroyed, added ATS.
No one was injured.
Authorities in the area have said that the clean up and reconstruction of Bondo could take several years, with the damage estimated to be several million francs.
Mayor of Bondo Anna Giacometti said the authorities had already released 800,000 francs in aid.