A linear intensity model to investigate the causal relation between Calabrian and North- Aegean earthquake sequences

(M 2 5) is modelled as the sum of three separate effects according to the stochastic processes theory (Ogata et al. 1982): (1) Poisson occurrence of independent events; (2) self-excitation (i.e., triggering due to earthquakes of the same sequence); (3) external triggering due to the occurrence of earthquakes ( M 2 6) in an adjacent Parameters of the model have been estimated by the MAICE (Akaike 1974) criterion applied to the historical earthquake catalogues of the two regions (1600-1984). Results show that triggering of the Calabrian sequence that is due to earthquake occurrence in the Aegean region is the predominant effect. On the other hand the occurrence of Aegean events appears mainly Poissonian. The estimated probability for a Calabrian earthquake following the occurrence of an Aegean event increases with time, reaching its maximum after around 13 months. This time lag is interpreted as being due to stress-wave propagation mechanisms following the occurrence of moderate to large earthquakes in the Aegean region