Initialisation and evolution of the eruption at a glance. In all the panels, a magnetogram, with white to black levels, is present in the background to make the link with observations in Fig. 1. The colour map is saturated between −400 and 400 G for visualisation purposes. a) Initial magnetic configuration and Lorentz force at t = 0 s. The pink lines represent the magnetic arcade that was later on transformed into the erupting flux rope. The green to yellow colour map indicates a volumetric representation of the magnitude of the Lorentz force; yellow (green) is more (less) intense. b) Zoom-in at t = 0.23 s of the region defined by the grey rectangle in panel a. The horizontal components of the Lorentz force are shown with arrows in blue (negative) and red (positive), drawn at a height z = 2.2 Mm. Temperature iso-surfaces of 2 × 10⁶ K (red) to 4 × 10⁶ (yellow) are also displayed. c) Rising phase for t = 6.87 min, t = 9.92 min, and 12.59 min. The coloured lines represent the magnetic field lines corresponding to the flux rope. The colour of the field lines represents the vertical speed v_z in pink. The two lines in the xy-plane indicate the cuts where the tracking (T line in light turquoise) of the flux rope and the compression (C line in dark turquoise) analysis were performed.