A spark ignites a single tree. Will the fire spread across the entire forest or burn out in a small patch? The answer depends critically on forest density — the simulation reveals the sharp percolation phase transition that governs real wildfire risk.
Each tree cell follows three states: Empty → Tree → Burning → Ash. Fire spreads to adjacent trees with probability p. At a critical density (≈59.3 % on a square lattice) a connected cluster spans the grid — fire roars through. Below it, fires are contained.
Adjust Tree density and Fire speed before clicking Ignite. Try density 0.55 and 0.65 to see how close to the percolation threshold changes outcomes. Enable Wind to favour directional spread.
The 2018 California Camp Fire destroyed Paradise in under two hours, consuming 18 000 structures. Models based on percolation theory are now used by fire agencies to identify high-risk landscapes before fire season.