Thursday evening saw a large part of a mountain slope slide down towards the evacuated Swiss village of Brienz/Brinzauls.

Fortunately, the debris avalanche came to a halt just outside the village. However, the danger of a rock slide has not yet been averted.

After being evacuated just over a month ago, Thursday saw a large part of the 'island', the unstable slope area of the mountain nearby Brienz, break away and slide down the valley as a rock and debris avalanche.

In the darkness, nothing could be seen of the event at first. However, the sliding debris caused a lot of noise. The highest possible danger level was immediately declared, while a nearby railway line and road were closed.

Friday morning revealed the extent of the debris flow. The road at the western end of the village was buried by yards of rock. The debris also buried a hut next to it. Fortunately, the avalanche stopped a few yards before the first residential buildings.

It is still unclear whether there was any damage to houses, for example due to flying rocks. The slope is now being examined by geologists. The area is to be flown over by helicopter. At present, it cannot be ruled out that further landslides or rockfalls will follow.

Previously, the movement of the slope accelerated sharply. The section was sliding downwards at 3 to 5 metres per day on Thursday.

Brienz has been evacuated since May 12th. However, the landslide has been going on for several years. This spring it accelerated faster and further than previously seen.

The cause of the Brienz landslide is the nature of the subsoil. The sliding slope stands on a smeary layer of clay. In contrast to other rockfall-prone areas in the Alps, thawing permafrost does not play a role here.