## 5 Discussion
All the aforementioned factors make it excessively difficult or even impossible to fully apply conventional methods for rock slope stability analysis in sites such as Egremnoi and Porto Katsiki. They would be time-consuming and expensive due to the equipment that must be used for the researchers' safety during field survey, while the results will only refer to accessible parts of the slopes as most of them will be excluded due to inaccessibility. On the contrary, the application of UAS-aided photogrammetry and TLS surveying offerexamination of the Egremnoi and Porto Katsiki slopes, through a highly localized lens across all parts of the surfaces under study. Furthermore, the large number of planes identified in the studied slopes (14,849 discontinuity planes from UAS in Egremnoi and 23,380 facets from TLS in Porto Katsiki) is at first essential for the thorough study of the deformation and then for the determination of the potential for failures along the slopes, either by one structure or by the synergy of two or more structures, which in turn reveals individual parts of the slopes susceptible to failures in the case of important external loads applied during an earthquake. The large number of data recorded during the application of these methods as well as the speed with which these data are processed is a significant advantage over conventional methods [109]. In addition, it should be noted that the UAS- and TLS-derived datasets are available for capturing on-demand data in the sense that the surveyor chooses the exact desired time of recording the study area and all of its features. This is an advantage compared to other image-exploitation approaches (e.g., satellite imagery analysis), especially when it comes to disaster management, in which capturing the natural processes is time-sensitive. In addition, UAS and TLS data capturing do not have the limitations of cloud cover. Furthermore, the capabilities of the UAS and TLS surveys fit the opportunistic nature of surveying a geometric phenomenon in the sense that the required equipment can be rapidly deployed in the field to collect information (e.g., after morphological changes), within the short time window that it is available (i.e., slopes affected by cleanup works). With respect to the field data gathering process, the suggested approaches have important benefits. Firstly, the segment of the coast under examination can be revisited virtually (back at the lab) at a later time, as the geometrical data captured are stored and can be reused, which is also essential for multi-temporal processing. This is particularly useful in the case of remote sites or unsafe areas. This availability of terrain data for a part of the coastal cliffs/zone allows the processing of multiple parts, permitting a more holistic study of the conditions. In this way, the captured scrap information in the form of a DSM offers increased flexibility and provides the opportunity to perform different trials on the study site, depending on the prevalent risk (e.g., a housing complex on top of the hill or an area filled with visitors). The very high resolution provides a description of the slope in very high detail, with nodes every few centimeters. This is a strong advantage of this approach, as it increases practicality, reduces time and personnel needs and minimizes safety concerns, especially considering steep slopes and inaccessible areas that would otherwise be surveyed using handheld instruments, putting surveyors at risk. In highly touristic areas of special natural beauty, such as the coastal areas in the western part of Lefkada, the interpretation of data originating from either UAS-aided photogrammetry or LiDAR scanning is not only an important scientific innovation for assessing the landslide susceptibility of slopes, but also a significant tool in the direction of responsible and effective management of coastal areas through the cooperation of authorities involved in the prevention and management of disasters from natural hazards.