Long-range time-correlation properties of seismic sequences

We performed the Allan factor analysis on the temporal distribution of seismicity of Italy from 1983 to 2002. Significant power-law temporal behaviour has been identified analyzing both the full and the aftershock-depleted seismic catalogues of Italy; this suggests that the correlated behaviour is due not only to the generation of aftershocks, following the occurrence of large shocks, but is a feature of the background seismicity.