Self-similarity properties of seismicity in the Southern Aegean area

We investigate the time self-similarity properties of seismicity in the Hel lenic are, which is one of the most rapidly deforming and seismically activ e regions of the Mediterranean area. The presence of time-scale-invariance properties in the shallow and intermediate depth seismicity is revealed. In particular, 1/f(beta) fluctuations are detected from the analysis of earth quake sequences using the counting statistics methodology. The shallow seis micity is characterized by a time clustering effect and shows a beta value that is a typical fingerprint of self-similar behaviours, whereas the inter mediate seismicity can be considered as a realization of a purely poissonia n process. The investigations cover instrumentally recorded earthquakes occ urring between 1964 and 1996, and the analyses have been carried out, selec ting different magnitude thresholds. The beta value for shallow seismicity decreases from almost 0.5 to 0.2 as the threshold magnitude increases from 3.3 to 4.5. (C) 2000 Elsevier Science B.V. All rights reserved.