Kinematic properties of the regions with elevated velocity dispersion. Left panel shows the relation between the estimated expansion velocity (V_exp) and kinematic age of each region (grey points). Blue points correspond to the regions classified as ‘Shells’, and light-blue crosses – to the values of V_exp for that sub-sample predicted from the analytical model (Eq. (9)) based on their estimated kinematic age and the properties of the star clusters. Top histograms in right panel shows the distribution of the kinematic age (blue colour) and the mean age of the clusters (weighted by their total mechanical energy input during the last 10 Myr; orange colour). Orange colour on the bottom histograms considers only clusters older than 4 Myr and corresponds to the time passed since the first SN (assuming it is happening at 4 Myr according to Fig. 6). Only the regions with at least one stellar association or star cluster are shown.