## 6 New Outcomes  
### New Data for the Metaxa Mine by IVR and GIS Tasks  
In this research, data concerning the Metaxa Mine was collected surveying the area in IVR, flying in drone mode within the scene, using GeaVR software as shown in the following video: [[https://youtu.be/Mw1c2503](https://youtu.be/Mw1c2503) qAo]([https://youtu.be/Mw1c2503](https://youtu.be/Mw1c2503) qAo). Thanks to this approach, we were able to map the entire upper boundary of excavation in the mine, as well as the natural debris flows and anthropogenic debris, and the outcropping boundary between eruption phases (Figure 10). This was accomplished even though the study area is situated along the vertical cliff continuously affected by debris and rock falling, preventing classical field survey.  
Of the LBA-phases, Phase 3 is the only one missing in the mine, whereas the boundaries between phases P0, P1 and P2 can only be seen where the famous section is located at the entrance of the mine (Figure 10e), due to extensive debris flows that cover the lower parts of the cliffs. Therefore, only the outcropping boundary between Phases 2 and 4 was digitized, while a new element, the upper boundary of debris flows as well as areas with anthropogenic debris were recognized and digitized with high (centimetric) accuracy.  
We measured the thickness of eruption phases wherever this was possible along the cliffs. First, we noticed that the thickness of eruption Phase P4 ranges from 1.7 m to 7.2 m. This wide range of values can be attributed to the different degree of surface erosion. The thickness of eruption Phase P2, as measured in the famous section, presents a value of 12.68 m, whereas measurements all around the mine show values ranging from 7.31 m to a maximum of 17.8 m. The more limited values can be attributed to the extended debris flows that cover the lower parts of the cliffs. The maximum values for both eruption phases are scattered along the southern and eastern cliffs.  
Furthermore, by interpolating the digitized boundary between Phases P2 and P4, a surface was generated, which suggests that the boundary presents an increased elevation in a southwest to northeast direction and a dip to the south.  
Figure 12: Different view angles of the estimated interpolated surface between eruption phases P2 and P4, along with the elevation points digitized in GeaVR.  
Regarding the volume of excavation material, using two photogrammetry-derived DSMs, one representing the area as it was back in 1960 and one representing the present-day one, we estimated a volume of 1,660,141.89 m\({}^{3}\) that corresponds to the northern part of the entire area named the Metaxa Mine (Figure 2b), which is in accordance with the volume estimated by [PERSON] et al., (2019) [19] and [PERSON] et al., (2020) [10], who mentioned that about 1.3 million m\({}^{3}\) was excavated in the early years of mining from the area left to the famous section, whereas a total of 4.5 million m\({}^{3}\) is estimated to have been extracted from the whole area (Table 4). Their estimation was based on a digital terrain model dated in 2018 with a pixel size of 2 cm. Particularly, based on our calculation, the volume of the excavated material that corresponds to Phase 4 was estimated to be approximately 24% of the total studied area. Finally, to present all data collected using the IVR approach, a thematic map was produced summarizing all figures mapped, as well as the location of quantitative measurements (Figure 13).