Self-similarity properties of seismicity in the Southern Aegean area

Abstract

We investigate the time self-similarity properties of seismicity in the Hellenic arc, which is one of the most rapidly deforming and seismically active 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 β fluctuations are detected from the analysis of earthquake sequences using the counting statistics methodology. The shallow seismicity is characterized by a time clustering effect and shows a β value that is a typical fingerprint of self-similar behaviours, whereas the intermediate seismicity can be considered as a realization of a purely poissonian process. The investigations cover instrumentally recorded earthquakes occurring between 1964 and 1996, and the analyses have been carried out, selecting different magnitude thresholds. The β value for shallow seismicity decreases from almost 0.5 to 0.2 as the threshold magnitude increases from 3.4 to 4.5.