Possible systematic variations in earthquake occurrence and fluctuations in seismicity behaviourof two seismically active regions in Greece which share common seismotectonic properties, is the aim of this study. Mygdonia graben in northern Greeceis characterized by arather moderate background seismicity, with small earthquakes between 2008-2012 whereas Corinth Gulf in southern Greeceexhibits a constantly high seismicity rate with several seismic activations during the recent instrumental period or before. The statistical approach of seismicity was accomplished, regardingthe magnitude, the inter-event time and distance for recent seismicity as a tool to quantify complex earthquake occurrence ordense spatial andtemporal clustering. For this reason, complete catalogues were compiled for the time period of the study. Probabilistic tests such as the smoothed bootstrap test for modality and bump–hunt were employed in order to unveil the complexity of the probability density function distribution of the above parameters. On the other handspatial earthquake distribution wasalso investigated under the frameof their fractal properties since the fractal coefficientcan largely express the clustering degree of seismicity. The goal of this stochasticanalysisis the quantification of the differentiationin seismicity propertiesinthese two important seismogenic normal fault populations in the back arc Aegean area.