Sensitivity of Simulated Proximal Lava-Flow Routing to DEM Choice at Mount Slamet, Indonesia

Digital elevation model (DEM) choice can alter stochastic lava-routing results where crater rims, depressions, and narrow channels are represented differently. We compared four source-location tests at Mount Slamet: an interpreted southwest-trending channel, the central crater, the western rim, and the southern crater. The elevation products were a 0.530 m unmanned aerial vehicle (UAV)-derived surface elevation model, Indonesia’s 8.29 m national DEM (DEMNAS), and 30 m Shuttle Radar Topography Mission (SRTM) data. Each DEM–source combination was run four times with 1500 trajectories per replicate. The analysis distinguishes native-grid summaries from common 30 m support and reports visitation-weighted radial reach, trajectory runout, directional concentration, convergence, and termination. The channel test retains a concentrated southwestward distribution on all three products. The other UAV tests remain close to their source cells and have weak directional concentration, so their bearings do not define a clear preferred direction. Regional products generally produce broader and longer distributions, but the response varies among source locations and is not monotonic with cell size. Frequent routing-exception stops and contrasting scales of fixed routing corrections identify unresolved numerical effects. The comparison demonstrates sensitivity to DEM choice under fixed inputs; it does not establish UAV superiority, eruption probability, or validated inundation limits.