On the group of Brenta Dolomites there was an important new rock detachment: last August 1, at 20:46, a portion of the west side of the Cima Falkneralmost 3,000 meters above sea level. The collapse, also detected by the seismographs and sighted by the staff of a refuge, caused a huge cloud of dust. According to the estimates, during the collapse they would have detached themselves among the 300,000 and 400,000 cubic meters of rock.
Roccia detachment took place less than a week after the last episode, recorded the July 27th: in this case, however, the energy freed from the collapse was 32 times higher And he even caused a change in the mountain profile. At the moment, the situation is carefully monitored through drones, laser And 3D reliefs.
We therefore see the causes of this detachment and because, according to geologists, in the coming months it is likely that others also occur subsidence.
The causes of the collapses and the importance of permafrost
First of all, it must be specified that, although it is of great impact, these collapses represent a natural phenomenon: all the mountains and reliefs, in fact, are destined to reduce their height over time. After all, it is one geological law: Raise is temporary, while erosion is perennial.
Behind the slow erosion of the mountains there are clearly several atmospheric agents, but also physical and chemical phenomena: fracture, thermal dilation, water infiltrations or frost. Among other things, the higher the mountains and the greater their exposure to these phenomena.
But what are the causes which caused the collapse of the west side of Cima Falkner? In this specific case, it was the permafrost to play an important role. At high altitudes, in fact, the rock is often kept together by the permafrost (i.e. a frozen soil for at least two years), with the ice that acts as a real natural glue.
Due to the temperatures, the permafrost is starting to merge In depth, transforming itself into a dough of water, sand and earth and causing landslides, avalanches and surface structural sagging. In other words, once the glue fails, The wall destabilizes And it is more likely that collapses like that of 1 August take place.
The mechanisms that weaken the rock: cryoclastic and thermoclasticism
Obviously, there is not only the permafrost behind an important collapse such as that which occurred in the group of the Brenta Dolomites: the causes depend on a set of different mechanismswhich also act for hundreds of thousands of years.
In particular, two mechanisms act on the weakening of the rock:
- The cryoclasticismthat is the classic process of frost: in this case, the water enters the fractures of the rock, freezes and consequently yes expand. When the water ice, it increases in volume and acts as a leverage in the rock. Whenever this process is repeated, the rock weakens, until they verify real fractures.
- The thermoclasticism which, on the contrary, is linked to thermal changes. When a rock is heated by the sun and then cooled quickly, they are created internal voltages. The different materials dilate and contract in a different way and, in the long run, this causes fractures, detachments and collapses.
These two phenomena act every day, especially in the high mountains, where thethermal excursion Between day and night it can also exceed 30 degrees. Since the rocks already weakened for millennia of erosion is then, it is still likely to generate landslide or sagging.
At the moment, however, Cima Falkner remains under observation. The geological service of the Autonomous Province of Trento is monitoring the area with drones, laser And 3D reliefs: the fractures will then be mapped and controlled. In the meantime, the authorities have confirmed the closure of the paths number 305 and 331 due to the instability of the rock.
