Fig. 1

Schematic diagram illustrating how distance-to-ocean \(D\) and distance-to-ocean along the primary dispersal axis \({D}_{PDA}\) were obtained for each eruption in our database. For caldera systems with no clear peak, eruptive centres were determined by taking the ejecta point source defined in the associated literature. Note that the geography depicted here is for illustrative purposes only and these two cases do not relate to a specific eruption