Description
Various techniques are used including:
- precision topographic monitoring using total optical station, level and GPS instrumentation
- monitoring with surface geotechnical instrumentation (strain gauges and crack gauges) also arranged for continuous data transmission
- monitoring with borehole geotechnical instrumentation (inclinometers);
- monitoring and measurement of the underground water table (with piezometers);
Various high-precision topographic geodetic monitoring networks have been set up and are periodically measured.
The purpose of monitoring in this way is to truly and volumetrically delimit landslide phenomena and to study their spatio-temporal evolution.
The Geological Survey has also identified and experimented with some of the innovative monitoring technologies that scientific and technological evolution is proposing. Among these, S.A.R. satellite interferometry and G.P.S. satellite systems are the technologies, now mature, that guarantee the greatest precision in the study of landslide phenomena affecting the slopes of Alpine valleys.
A fixed geodetic GPS station has been in operation at the Geological Service headquarters since 1996, and the data collected are supplied to the University of Padua, which, by processing them with those collected in other parts of the Alpine chain (Turin, Graz, Grasse, Padua, Venice, Genoa, Bolzano, Matera, Villach, etc.) and always within a European reference context (EUREF), is able to define any crustal deformations of the chain itself.
The data collected by the Geological Service station in Trento are also supplied, upon request, to other provincial services (Forestry, Sanitary Works, Road Heritage Management, etc.) and to external users such as, for example, the University of Trento, the Adige River Basin Authority and freelance professionals. These data allow differential corrections for the processing of precision topographic surveys and surveys for the location of points or lines on the P.A.T. technical map.
The Geological Survey is also equipped with other GPS receivers with geodetic characteristics that allow the precision survey of certain landslide movements on its territory.
In addition, fixed precision monitoring networks have been set up to measure active phenomena or phenomena believed to be active. A network has been set up in correspondence with the tectonic structures linked to an important tectonic lineament called Schio-Vicenza, and other measuring stations cover the Insubric lineament.
There are currently four landslides being monitored by GPS and two of these are equipped with fixed receivers with continuous data transmission.
Satellite radar interferometry, on the other hand, can be used as a remote monitoring tool for landslide-prone areas.
The Geological Survey is experimenting with the use of SAR satellite images for the periodic and capillary monitoring of movements of buildings and infrastructures located on landslide bodies. In the near future, the SAR data necessary for monitoring the entire provincial territory will be acquired with the aim of identifying and studying any surface and deep movements that can only be perceived instrumentally.
Interferometric techniques make it possible, in fact, to measure displacements of subcentimetric entity and these can represent precursor clues to events (e.g. reactivation of quiescent landslides).