A catalog of aftershock sequences in Greece (1971-1997): Their spatial andtemporal characteristics

A complete catalog of aftershock sequences is provided for main earthquakes with M-L greater than or equal to 5.0, which occurred in the area of Greec e and surrounding regions the last twenty-seven years. The Monthly Bulletin s of the Institute of Geodynamics (National Observatory of Athens) have bee n used as data source. In order to get a homogeneous catalog, several selec tion criteria have been applied and hence a catalog of 44 aftershock sequen ces is compiled. The relations between the duration of the sequence, the nu mber of aftershocks, the magnitude of the largest aftershock and its delay time from the main shock as well as the subsurface rupture length versus th e magnitude of the main shock are calculated. The results show that lineari ty exists between the subsurface rupture length and the magnitude of the ma in shock independent of the slip type, as well as between the magnitude of the main shock (M) and its largest aftershock (Ma). The mean difference M-M a is almost one unit. In the 40% of the analyzed sequences, the largest aft ershock occurred within one day after the main shock. The fact that the aft ershock sequences show the same behavior for earthquakes that occur in the same region supports the theory that the spatial and temporal characteristi cs are strongly related to the stress distribution of the fault area.