Moving group detection in different neighbourhoods along the radial direction. For each moving group a parabolic fitting of the substructures associated with each group is included (highlighted in grey). Each moving group contains several structures, corresponding to different V_R bins. The largest structure in each group is used as its representative (dots with larger black contours and the moving group name on top). There are two examples of bimodalities, which serve as evidence of the complex evolution of the arch morphology (Sirius at R = 8.16 kpc and Arch/Hat at R = 10.4 kpc).