The direction of maximum spread in anisotropic forest fires and its critical properties

Some new critical properties related to the spread along the anisotropy axis of directed percolation as a model for wind-biased forest or wild land fire, are introduced and discussed. We show that it is possible to extract the burned mass along the axis, its appropriate exponent, and the gap exponent for successive bulk moments of the total burned mass from Monte Carlo studies at the critical probability. We provide evidence for a new, analogous exponent for the mass burned on the axis and propose a scaling relation for it, based on the numerical evidence.