Fig. 1

Volcanic field examples. a Harrat Rahat vent locations, shaded area represents lava flow field; b Harrat Rahat vent density distribution; c Auckland Volcanic Field vent locations; d Auckland Volcanic Field vent density distribution. Vents are shown as black marks, North is up. Vent density contours at [0.05, 0.5, 1, 5, 10, 20, 50, 80] % of maximum density