Landslide monitoring
An integrated monitoring system was installed to assess the speed of the landslide, to be able to measure the surface movement of the landslide and programme the actions to be taken for assuring the safety of the area and infrastructures involved.
SAR system
On 29th April 2010 the DST-UNIFI Competence Centre installed a land based radar system (GBInSAR LiSALab) (together with the ElleGi srl – LiSALab companies).
This system continually records data and processes a radar image every 4 minutes to be able to monitor the instability in real time. As the instrument has been installed on the opposite side to the landslide it is also able to monitor the lower portion and foot of the landslide.
The displacement of the landslide is measured by examining the interferograms, that is the difference between two radar images.
Average speeds vary between 2.5 metres day, measured on the summit of the foot of the landslide (sector B), to 1.1 metres per day, observed in the right hand sector of the foot of the landslide involved by the re-profiling works on the hillside (sector D).
Topographic stations
The CNR-IRPI Operations Centre, a geomonitoring group in the Turin section, started up a topographic monitoring system to measure the speed of displacement in various areas of the central part of the slide.
The monitoring systems installed are:
- a complete robotized station installed at the front of the landslide, working since 29/04/2010. The input gives no indication of major displacements.
- a complete robotized station on the right flank of the accumulation area of the phenomenon, where material is currently being removed and re-profiling works are in progress since 30/04/2010. The monitoring data shows that the principal landslide phenomenon travels at a speed oscillating between 2.0 and 2.60 meters per day, whilst the secondary slide phenomenon travels at a speed of between 3.60 and 4.20 metres per day.
- a complete manually controlled station plus relative network of topographic posts installed in the central area, to the left of the area of accumulated material and re-profiling works in progress since 4/05/2010. The data shows that displacement speeds oscillate between 1.40 and 1.90 metres per day, at a steady speed; the values are less than centimetre/hour from an altimetry point of view.