Description
The substrate of the studied area consists of metamorphic type rocks belonging to the Ortles-Campo stratum. In particular, it consists of garnet and staurolite micaschists that geologically belong to the Peio Unit. The rocks of the substratum are subject to intense meteoric degradation and morphogenetic processes linked to the action of gravity and frost are active in the area. Until the recent past, the summit slopes of the Vioz ridge were also affected by glacial processes, due to the presence of two glaciers that are now very small in surface area and volume (Vallenaia Glacier on the eastern slope and Central Vioz Glacier on the western slope).
Permafrost monitoring at the hut began in 2010 with continuous measurements of the ground surface temperature (GST). For this purpose, four temperature sensors connected to data loggers were placed around the hut, which allow hourly scanning measurements. The instruments are autonomous and require only annual maintenance, for data download and battery replacement. This methodology makes it possible to acquire data to characterise soil temperature conditions and calculate some important variables that indicate the presence of permafrost and its evolution over time.
The soil temperatures recorded over 13 years of measurements indicate annual average values varying but between -2°C and -4°C. suggesting that the subsoil in the area under investigation is in permafrost conditions. The average monthly temperatures show a slight upward trend over the time period considered, at least for three of the four sites investigated.
During a number of inspections carried out in July 2022, it was observed that the section of the ridge leading from the hut to the summit of Monte Vioz was affected by numerous longitudinally arranged cracks, up to a few metres long and a few decimetre wide. Some of them affected the base of the small room housing the water cisterns serving the hut, located along the ridge. The hypothesis was that the very high summer temperatures had accelerated an already ongoing phenomenon and that the degradation of the permafrost could be one of the possible causes.
In order to observe any active movements of the fissures and the ridge section upstream of the hut, a Ground-Based Synthetic Aperture Radar (GB-SAR) was installed, which, using interferometric techniques, allows centimetric movements to be detected with a temporal resolution in the order of minutes. It is an 'active' observation instrument, capable of emitting very short but intense electromagnetic pulses in the microwave range and 'illuminating' a more or less large area of landscape. The instrument receives the possible backscattered signal from the scene-energy pulse interaction and constructs an image of the latter signal, which contains not only the retroreflected power but also the phase of the signal.
The instrument operated continuously from 13 to 30 August 2022, making an acquisition every 30 minutes, recording displacements of up to several tens of centimetres in 15 days.
The Geological Survey considers it necessary to refine its knowledge of the morphogenetic processes linked to the degradation of the permafrost along the Monte Vioz ridge.
La cresta del monte Vioz. In primo piano il rifugio.
La cresta del monte Vioz, ripresa dalla Val de La Mite
L'interferometro che ha operato sul monte Vioz nell'agosto 2022
As part of these activities, a synergy was established with CNR-ISAC, CAI and SAT, which led to the installation of a weather station near the Vioz Refuge. This activity was completed on 29 and 30 August 2024.
Data on air temperature and humidity, pressure, wind speed and direction, precipitation and solar radiation, together with spectacular webcam images, are available at https://rifugisentinella.cai.cnr.it/rifugio-vioz-meteo/.
La stazione meteo installata nell'agosto 2024
La stazione meteo installata nell'agosto 2024
On 18 September 2024, a geophysical survey campaign was conducted along the ridge of Monte Vioz to determine the presence of permafrost in the subcortical band of the rock mass. Seismic surveys combined with medium-high resolution electrocotomographic surveys were carried out.
Indagini geofisiche eseguite a settembre 2024
Indagini geofisiche eseguite a settembre 2024
The following day, a GBInSAR instrument was installed at the mountain station of the Peio 3000 cable car with the aim of monitoring the morphogenetic phenomena affecting the south-western slope of Monte Vioz.
The monitoring is conducted in 'periodical check' mode with the aim of defining, through different measurement campaigns, sectors of the slope characterised by different kinematic behaviour.
L'interferometro GBInSAR installato nel mese di settembre 2024
GBInSAR interferometer video installed in September 2024
Click on the image below to view the latest shot from the Vioz webcam:
Le immagini della webcam sono tratte dal sito https://rifugisentinella.cai.cnr.it/rifugio-vioz-meteo/