Geomatics for slope stability and rock fall runout analysis: A case study along the Alta Tambura road in the Apuan Alps (Tuscany, Italy)

With increasing awareness of geological risks, the study of rocky slopes plays a key role in the Earth Sciences, especially in areas of high vulnerability due to the presence of human settlement. The present paper describes the stability and runout analyses carried out along the Alta Tambura road, in correspondence with the Guadine village connecting the Massa urban settlement to the Apuan Alps (Tuscany, Italy). The integration among various types of survey and analytical methodologies allowed for the application of up-to-date approaches for hazard assessment. Results from these types of studies are useful in the decision-making process concerning choosing the most appropriate mitigation works and, as in such a case, their a posteriori validation. With regard to the survey techniques, terrestrial laser scanning and digital close-range photogrammetry were used to produce the digital elevation model, oriented stereo-images, orthophotos and accurate positions and volumes of rocky wedges and joints located on the slope overhanging the analyzed road. Thanks to this data, a deterministic stability analysis was conducted and the spatial distribution of rock fall density, velocities and kinetic energies was modeled by means of the "cone-method". Historical evidence of rock falls, identified during fieldwork activities and photointerpretation, were used to assess and calibrate the accuracy of results obtained from the method and allowed, through a further 2D rock fall runout analysis, the calculation of the dissipation energy that protection measures need to mitigate the risk in the area.