A fractal approach to the temporal distribution of microseismicity at the low eastern flank of Mt. Etna during 1989-1994

Seismicity affecting the low eastern flank of Mt. Etna shows clustering in time. We analysed a catalog of microearthquakes recorded by the four stations of the Osservatorio Sismologico di Protezione Civile di Acireale during the period 1989-1994. In general a strong deviation from periodic and random distribution was found. The temporal clustering is scale invariant and a fractal dimension can be derived to characterize it. Fractal dimensions seem to be correlated to the beginning of two major eruptions.