Joint distribution of the combined events maximum area A_max and their duration D, for periods 1 (cyan) and 2 (magenta). The curves are level lines of the joint empirical probability distribution of A_max and D, obtained by dividing a 2D histogram of these quantities by the number of data points and by the area of each bin (bins are spaced exponentially); probabilities associated with different curves are spaced exponentially and are separated by a half decade, from low probabilities (light colours) to high probabilities (dark colours). Linear fits of D(A_max) are overplotted and their slopes are shown above the plot.