Gudrun Dreiås Majala, a geologist with the Norwegian Water Resources and Energy Directorate (NVE), said rain had increased the risk that the unstable Veslemannen, or “little man”, structure in the Rauma municipality would collapse, dumping 100 million cubic metres of rock onto the valley below.
“The mountain has responded much faster than it has earlier, despite the relatively small amount of rainfall,” she told state broadcaster NRK. “This gives us a signal about how unstable the part in danger of falling has become.”
The Veslemannen structure has shown signs of instability since 2014, with the NVE and other agencies predicting that it will collapse imminently.
The directorate last year attempted to remove the danger by inducing a controlled landslide at the site, by pumping water into cracks in the mountain. But geologists abandoned the effort last October.
As well as evacuating residents, police in Møre og Romsdal on Friday afternoon also announced a ban on all road and rail traffic beneath the mountain.
Farms and holiday homes under the mountain have been evacuated in late summer or early autumn every year since October 2014, when the speed of movement at the structure accelerated rapidly, leading to fears that a collapse was coming.
Since then, residents have been evacuated in September 2015, August 2016 and October 2017, without the long-awaited landslide coming to pass.
The mountain has been monitored closely since 2009.