At the Grange Orgiera landslide a topographic monitoring network has been installed on August 2009.

The topographic network has located upstream Grange Orgiera hamlet, in correspondence to the left frontal lobe of the landslide. The network consists of a robotic total station, associated to a solar panel and a backup battery that guarantees its operation, and a GSM modem that allows a download of the data by remote connection; eight prisms, seven of which inside the landslide and one close to the landslide foot, and two reference points outside the landslide. This network allowed the monitoring of the left frontal lobe of the landslide, which threatened the Puy village.

The topographic network was installed on July 2009 and recorded during the spring-autumn months, in particular from August 2009 since October 2009. In 2010 have been installed five new prisms within the landslide body, near the left frontal lobe of the landslide, and the monitoring network recorded from July 2010 to September 2010.

The monitoring network allowed several automatic displacement measurements of the prisms inside and outside the landslide, using a robotic total station Leica TCA 1800. This high-performance instrument for the ground displacement surveying, allow to measure the angle (Hz and V) and distance measurement. Data collected by this total station permit to improve knowledge on surface ground deformation, and the geomorphological evolution of the landslide.

In particular, the TCA 1800 total station used is characterized by:

- Angle-measurement accuracy: Standard deviation (ISO 17123-2) of 1” (0.3 mgon);

- Distance measurement (IR): Standard deviation (ISO 17123-4) 1mm + 2 ppm; Range 2.500 m, under average atmospheric conditions, i.e. visibility 15 km.

- Automatic target recognition (ATR), under good atmospheric conditions: Accuracy at below 200 m of 1 mm; Accuracy at 500 m of 2 mm – 3 mm.

For more information:

http://www.leica-geosystems.com/downloads123/zz/tps/tps2000/brochures/tps2000_brochure_it.pdf