Fig. 4

Relationship between the ratio of total erupted ash volume (V_FALL) to total volume erupted (V) and eruption magnitude for the 74 eruptions considered, filtered by their distance to nearest ocean (\(D\); a-d). Plots shaded by grey (\({D}_{PDA}\); e–h) filter eruptions based on their distance to nearest ocean if travelling in the direction of the primary ash dispersal axis listed in the literature. The significance of relationships is determined by Pearson’s correlation analyses, with R² values displayed here to indicate the ‘goodness’ of fit for the linear model applied to the two variables (full results in Table S3). Error bars are marked in grey, and calculated according to the uncertainty estimates given in the source literature or assigned where these values were unavailable (see methods)