Fig. 3

FlowDIR output for forecasting the directionality of the 2018 lava flow at Shinmoedake volcano (Japan), the travel direction of the flow (the sector of the crater wall that was overtopped by lava) was between 290–323° bearing from the starting location and is shown in all panels with a red shaded area. a The DEM used for simulations (Geospatial Information Authority of Japan, 5 m resolution) with initialisation points (N = 289) shown as red crosses (please note these crosses overlap), and the crater buffer outlined in black. b The travel direction probability for each secondary intercardinal direction bin, calculated using the azimuthal elevation difference (AED) functionality. The standard error on the 289 initialisation points is shown for each bin as a red bar (very small for Shinmoedake) located at the wider end of the probability bin. Diamonds at each bin’s centre point depict the elevation difference, where larger markers show directions that exceed the elevation threshold (unlikely to be overtopped). c The least cost path (LCP) matrix, which shows the summed inverse propagation step number for each cell in the path taken from the initialisation point to the buffer limit, over all initialisation points shown in panel a, with more likely exit points indicated by higher values at the buffer limit. For Shinmoedake, due to the very flat summit topography and the high resolution DEM a highly sinuous path is taken. d The elevation profile for the buffer extent as outlined in panel a