The five cross-sections used as mechanical prototypes. Cross-section A corresponds to the ECORS profile, redrawn after Schmid and Kissling (2000) and Philippe (1995). Cross-section B has been redrawn after Burkhard and Sommaruga (1998), and cross-sections C, D and E are original, based on Pfiffner et al. (1990), Sommaruga (1999), Rotstein et al. (2006), Ustaszewski and Schmid (2007) and Sommaruga et al. (2012). The cross-sections are aligned along the vertical dashed line showing the limit between the Jura and the Molasse basin. The mechanical properties of each material are presented in Table 1. A horizontal compressive force Q is applied on the crust along the southern wall (red arrows). The vertical fixed wall with green dashed lines on the left precludes any horizontal movement and allows any vertical movement. The fixed base, with green hash signs, precludes any horizontal and vertical movements. We also consider an alternative prototype where the force (Q₂) is applied on the upper crust only, and where we introduce a detachment D₂ between the upper and lower crusts.