## 3 Methods
### Data Collection on 2-D and 3-D Outputs  
Once the resulting models had been processed, we imported the DSM and the orthomosaic in a GIS environment and mapped all fractures in the area, and remapped all post-LGM and LGM stratigraphic units (Figure 6a): these steps have been made possible thanks to the very high-resolution of the orthomosaic. Fractures have been further classified as normal faults when associated with a continuous and appreciable, and persistent, vertical offset \(>0.5\) m, calculated on the DSM, whereas they have been classified as extension fractures when associated with vertical offset less than 0.5 m. Apart from the DSM, the use of the 3-D tiled model, that can be defined as a virtual outcrop [82; 83], has been crucial in order to perform visual checks in key points of each examined structure. Such models can be used for observation using an immersive virtual reality [31; 64; 65; 84] and non-immersive virtual reality [85] approach as well as 3-D visualisation on a computer workstation [82].  
Different types of quantitative data have been taken: along normal faults, we quantified the strike and the vertical offset, by measuring differences in altitude along 50-m-spaced topographic profiles traced on the DSM, orthogonally to the fault scarp, whereas along extension fractures we collected the strike, the amount of dilation and opening direction values. More in detail, wherever piercing points on each side of the extension fractures were clearly visible, we traced a line connecting them on the orthomosaic, and we calculated its strike and length to obtain the direction and the  
Figure 6: (**a**) Geological map of the area based on high-resolution outputs from SfM photogrammetry processing and field checks, reference system: UTM28-WGS84. LGM = Last Glacial Maximum; Rose diagrams representing the strike for the whole set of fractures (**b**), normal faults—including the dip direction of fault scraps—(**c**) and for extension fractures (**d**). For each set the av. value and standard deviation is represented as continuous and dashed lines respectively, the regional spreading direction range is reported as dark grey lines. (**e**) Fracture strike vs. length (for both extension fractures and normal faults), av. value is reported as a continuous line, the SD range is represented as a dashed line (box), and the regional spreading direction range is represented as a dark grey rectangle.  
amount of opening, respectively. All factors that could alter the accuracy of the resulting values have been avoided, by making sure to collect data only at fractures not affected by erosion and sedimentation, without falling rocks on their sides and far away from fault rims to avoid local gravity effects. For these quantitative measurements, we also used the SfM-derived 3-D model for some checks to better recognize all fault scarps and visualize piercing points. Finally, all collected data have been used for two aims: defining the spreading direction in the area and quantifying the overall extension rate during late Pleistocene and Holocene times. We calculated all horizontal dilation values along N105\({}^{\circ}\) E-trending transects, in order to obtain the cumulative dilation, stretch, and extension rate in the two main outcropping successions (LGM and post-LGM). These transects have been located in order to cover both the LGM unit and the post-LGM units. The N105\({}^{\circ}\) E is the mean value of the spreading direction given by [PERSON] et al. (2018) and [PERSON] et al. (2018), both considering geological data for a long-term time window.