Filamentation and splitting of diffusive regions at t = 328. Detailed treatment shows how the magnetic diffusivity is concentrated into multiple thin channels. The blue-line-bounded areas indicate the diffusion regions where the generalized anomalous resistivity (Equation (2)) is finite. Field lines are dashed to be better distinguished from the resistive region boundaries. The right panel displays a detailed view of the rectangular box in the left. Red and green lines are as in Figure 4.