  The research deals with a study of local fractality in spatial distribution
of forest fires in Portugal using the sandbox method. The general procedure is
the following: (a) define a circle centred in each and all events with
increasing radius R; (b) count the number of other events located within the
circle of radius R, N(R); (c) plot the growth curve which is the functional
dependence of N(R) versus R; and (d) estimate the local fractal dimension as
the slope on log[N(R)] versus log[R]. The computation is carried out by using
the location of every fire event as a centre but without the final averaging
over all the fires for a given R, which is usually performed to get a global
fractal dimension and to estimate global clustering. Sandbox method is widely
used in many applications in physics and other subjects. The local procedure
has the ability to provide the most complete information regarding the spatial
distribution of clustering and avoiding non-homogeneity and non-stationarity
problems. Most of the analysis was performed using the National Mapping Burnt
Area (NMBA) database which accounts for 32,156 fires during the 1975 - 2013
period. The results of local analysis are compared with a randomly generated
pattern in forest zones (validity domain). The results demonstrate interesting
local spatial patterns of clustering. Some results on global measures are
reported as well.
