Resumen
Rockfall consists one of the most harmful geological phenomena for the man-made environment. In order to evaluate the rockfall hazard, a variety of engineering geological studies should be realized, starting from conducting a detailed field survey and ending with simulating the trajectory of likely to fail blocks in order to evaluate the kinetic energy and the runout distance. The last decade, new technologies, i.e., remotely piloted aircraft systems (RPAS) and light detection and ranging (LiDAR) are frequently used in order to obtain and analyze the characteristics of the rock mass based on a semi-automatic or manual approach. Aiming to evaluate the rockfall hazard in the area of Nestos, Greece, we applied both traditional and structure from motion (SfM)-oriented approaches and compared the results. As an outcome, it was shown that the semi-automated approaches can accurately detect the discontinuities and define their orientation, and thus can be used in inaccessible areas. Considering the rockfall risk, it was shown that the railway line in the study area is threaten by a rockfall and consequently the construction of a rockfall netting mesh or a rock shed is recommended.