NThe residents of Brienz-Brinzauls are still not allowed to return to their mountain village. But they can hope to be able to enter their houses and apartments again soon. Because a large part of the rock masses that threatened the Graubünden village and therefore had to be evacuated a good four weeks ago, thundered down on Friday night with a great deal of noise. The houses below the community were spared.
Photos show that the rock masses came to a standstill a few meters in front of the first house in the village, the old school building, at an altitude of around 1100 meters. “Brienz was very lucky,” said Christian Gartmann, spokesman for the community, on Swiss radio SRF. The canton road and a log cabin on the meadow below the slope are buried under meters of rubble. Gartmann also pointed out that splinter stones could have flown hundreds of meters through the air like cannonballs and smashed into house walls and window panes.
The rockfall happened between 11 p.m. and midnight. It was very loud in the whole valley basin. The community’s crisis management team met twice during the night and evaluated photos at dawn.
After an initial and thus preliminary assessment, Gartmann assumed that more than half of the almost two million cubic meters of rock masses that geologists considered to be in acute danger of falling had slid. The geologists now have to investigate how great the risk of further debris flows or rockfalls is. “We are currently assuming that this was unfortunately not all,” said Gartmann. It is still unclear when the 85 residents of Brienz will be allowed to return to the village. “Until Brienz is completely safe, Brienz cannot be inhabited.”
Cameras recorded everything
The village has been locked down for weeks. Only installed cameras recorded what was happening 24/7. Huge boulders had already fallen on Wednesday. At first glance, everything remained lying on meadows in front of the village.
Before and after pictures now show the massive changes in the landscape. The day before, there were still bare rocks, single boulders, light and dark rock and meadow, trees and a wooden hut in the area. On Friday, all of this lay under a gigantic mountain of gray rubble. The village looks like a miniature complex in comparison to the pictures.
As a precaution, roads and railway lines below the village had been closed. Train traffic to the resort of St. Moritz will be diverted because the route between Tiefencastel and Filisur is closed, as a spokesman for the Rhaetian Railway said. The 6th stage start of the Tour de Suisse bicycle race had to be moved from La Pont to Chur on Friday.
Rock masses slid at a speed of 40 meters per day
Unlike the recent landslide in Tyrol in Austria, climate change is not the trigger in Brienz. Elsewhere, it is causing permafrost, the ice that holds rocks together at high altitudes like glue, to melt. Around 100,000 cubic meters fell in Tyrol last Sunday. Hundreds of meters of the southern summit of the Flughorn massif, including the summit cross, broke off. The rock material landed far away from inhabited areas and endangered no one.
The geologists had previously assigned a probability of 30 percent to a debris flow like the one that just happened. It is less dangerous for the village than a rock fall, in which rocks with a volume of up to several 100,000 cubic meters suddenly crash down.
The rock masses above Brienz have been moving for several millennia. For 140 years, the slope has been sliding faster than before, namely several centimeters a year. That is why it is closely monitored with a sophisticated measuring system. This week, the rock masses have already slid at a speed of 40 meters per day. The “island”, as the dilapidated rock section is called, is considered to be the best monitored mountain section in Switzerland.
