Side (a) and top (b) view of the magnetic field line topology of the second flux rope before its eruption (t = 314 min). The field lines are similar to the previous eruption and are coloured as in Fig. 6. Panels c and d: flux rope during the eruption at t = 318.5 min. Green field lines result from the reconnection of field lines similar to the blue field lines of Fig. 12a, and act as a strapping field to the eruption. Red field lines are formed by the reconnection of pink lines during the eruption of the flux rope core (orange). Panels e and f: magnetic field line topology at t = 322.8 min, when the eruption has stopped and the flux rope has been confined. The yellow field lines connecting the inner polarities (P1, N2) are the post-reconnection arcade loops.