Monofractal and multifractal characterization of geoelectrical signals measured in southern Italy

Abstract

Fractal tools have been used to characterize the temporal fluctuations in the dynamics of hourly geoelectrical signals, measured from January 2001 to February 2002 by four stations installed in Basilicata region (southern Italy). Three stations (Giuliano, Marsico and Tito) are located in a seismic area, and one (Laterza) in an aseismic area. Monofractal approaches (Lomb Periodogram, Higuchi method and detrended fluctuation analysis) have been used to identify in a wide range of timescales scaling behaviour, that indicates the presence of correlated temporal fluctuations and long-range dependence. The multifractal formalism leads to the identification of a set of parameters, derived from the shape of the multifractal spectrum (the maximum α 0, the asymmetry B and the width W) and measuring the “complexity” of the signals. Furthermore, the multifractal parameters have revealed to well discriminate geoelectrical signals measured in seismic areas from those recorded in aseismic areas.