  This paper is devoted to a phenomenological study of the earthquakes in
central Alborz, Iran. Using three observational quantities, namely weight
function, quality factor, and velocity model in this region, we develop a
phenomenological dissipative sandpile-like model which captures the main
features of the system, especially the average activity field over the region
of study. The model is based on external stimuli, the location of which are
chosen (\textbf{I}) randomly, (\textbf{II}) on the faults, (\textbf{III}) on
the highly active points in the region. We analyze all these cases and show
some universal behaviors of the system depending slightly on the method of
external stimuli. The multi-fractal analysis is exploited to extract the
spectrum of the Hurst exponent of time series obtained by each of these
schemes. Although the average Hurst exponent depends on the method of stimuli
(the three cases mentioned above), we numerically show that in all cases it is
lower than $0.5$, reflecting the anti-correlated nature of the system. The
lowest average Hurst exponent is for the case (\textbf{III}), in such a way
that the more active the stimulated sites are the lower the value for the
average Hurst exponent is obtained, i.e. the larger earthquakes are more
anticorrelated. However, the different activity fields in this study provide
the depth of the basement, the depth variation (topography) of the basement,
and an area that can be the location of the future probability event.
