RECURRENT PATTERNS IN THE SPATIAL-BEHAVIOR OF ITALIAN SEISMICITY REVEALED BY THE FRACTAL APPROACH

Three are the essential parameters needed to describe seismicity: the b-value of the Gutenberg-Richter relation and the spatial and temporal fractal dimensions (D(s) and D(t)). Several cases have been reported when a significant decrease in the b-value or in the spatial fractal d imension preceded major earthquake sequences or aftershocks. Here we u se the fractal method based on the correlation integral to study the t emporal changes in the spatial (2-D) distribution of earthquakes in th ree important seismic zones of Italy. In all three zones D(s) shows si gnificant variability, which correlates well with the major events and clearly marks the beginning and the end of an earthquake cycle. Final ly, the nucleation of most major events is associated with a fractal d imension value which corresponds to the topological dimension of a pla ne.