Fig. 2

Cumulative number of phreatic eruptions with time. Since we only considered the phreatic sub-dataset and magmatic eruptions could have occurred in gaps of phreatic activity, we cross-checked for magmatic eruptions in the original catalogue during longer periods of phreatic quiescence. Red vertical lines indicate periods of magmatic episodes during phreatic quiescence; red boxes indicate major magmatic episodes as identified by Scott (2013). Labelled grey boxes at the top indicate periods 1–4 with different explosion frequencies as discussed in the text