(a) Temporal variation of the mean shear ($\overline{\gamma }$) of the field lines anchored at FP1 (red curve) and FP2 (blue curve) for the simulation with strong initial shear (simulation 1), which has multiple flux rope eruptions. The vertical dashed lines are the time markers at t = 7.51 and 12.52 min, after which the reconnection occurs at those field lines. (b) Temporal variation of $\overline{\gamma }$ for the field lines anchored at different footpoints as shown in the legend for the simulation with a weak initial shear (simulation 2), which do not experience the formation of any flux rope.