Spatial fractal evolutions and hierarchies for microearthquakes in centralGreece

Statistical characteristics of seismicity represented by microearthquakes a re examined for three regions in central Greece, in particular the fractal correlation dimension, D-2, and traditional b values are examined in tandem as a function of time by using the moving window technique. The Patras reg ion contains the complicated tectonics, extending to damaging historical ea rthquakes of the western Corinth Gulf and the Rio Graben, yielding D-2 valu es between 0.40 and 1.20 with b between 0.94 and 1.27. unusually, the tempo ral evolution between D-2 and b generates a positive correlation, although the variation is mostly in D,. When the whole evolution is divided into two stages then the positive correlations are even stronger than for the whole evolution. The views of Henderson and others might suggest a highly fractu red, fluid-filled zone. The Pavliani region, with no known active fault, an d the Volos region, containing the through-going Nea Ankhialos fault, yield D-2 values 0.33 to 0.79 with b 0.92 to 1.30 and D-2 0.82 to 1.56 with b 1. 02 to 1.37, respectively. Temporal evolution between D-2 and b provides a t ypical negative correlation in both regions. Examination of gross seismicit y (time window embracing the whole data set) in each region produces D, val ues for the Patras and Volos regions that are both larger than that for Pav liani; there are no obvious differences amongst the b values. This accords with the knowledge that Patras and Volos are in regions with very active se ismotectonic features which generate repeated strong earthquakes exceeding 6 M-s. D-2 for both regions is fairly close to 1, the topological dimension of a line, consistent with seismicities on leading active fault zones or t hrough-going faults. These values highlight the ability for microearthquake s to illuminate the character of their parent tectonic province. Resolution and hierarchy in these data from Greece are compared with these aspects el sewhere (Japan, Turkey, South America, USA) in the sense that their banding with respect to examined magnitude, areal extent and duration of observati on period for respective data sets is examined in relation to the earthquak e potential of the parent seismotectonic province. Evolutions are then cate gorised as being macroscopic, transitional or microscopic in character.