Geomatics activities for monitoring the large landslide of Maierato, Italy

The paper discusses the contribution given by geomatics to monitoring operations regarding a large landslide. The phenomenon affects an entire hill at the edge of the town of Maierato, southern Italy, which bisected the main access road to the town. In the first year after the main event, several surveying methods have been performed by different institutions, often not coordinated. At the end of 2010, an agreement was stated between the Civil Protection Department and the CAMILab of the University of Calabria, regarding the realization of geological, geotechnical, hydrological, and hydraulic studies and surveys in the Municipality of Maierato. The aim is to set up a model of the evolution of the phenomenon and to obtain the periodic assessment of the residual risk level. For understanding the event deeply, the integration of a number of methods of investigation, both geophysical and geotechnical, with geomatics techniques has been performed. The final goal is to set up an early warning system. The used geomatics techniques are the following: total station (operating continuously), Global Navigation Satellite System (GNSS) surveys, laser scanner, and digital photogrammetry. The total station controls and transmits the position of 20 points continuously. The design of the control network and the data acquired during the first 11 months of monitoring are discussed. GNSS receivers are used in static mode for the reference points. Kinematic and RTK surveys have been made to obtain the cross sections, useful to interpret the geoelectrical tomography correctly. Laser scanner has been used to obtain a 3-D model of the area and to evaluate the volume of the landslide. The first 18 months of continuous monitoring show, on the one hand, an excellent repeatability of the measures, and on the other, they confirm the results obtained by geotechnical investigations (inclinometers, etc.) and surface surveys.