Figure 1 a) Thickness map of the erupted products in the Fagradalsfjall eruption by September 30, 2021. Vents are marked with a dot and numbered chronologically after opening time. Location of topographic profile in c) is marked as a yellow line. b) Map of the Reykjanes Peninsula. The red box indicates the area displayed in a). Densely populated areas are marked in gray. Volcanic systems (Sæmundsson and Sigurgeirsson, 2013) are marked with orange and denoted by capital letter according to their name; R: Reykjanes, S: Svartsengi, F: Fagradalsfjall, K: Krýsuvík, B: Brennisteinsfjöll, H: Hengill. c) Topographic profile along the vents from NE to SW (location see a).