Analysis of long-range correlations in geoelectrical signals measured in southern Italy

We investigate, by detrended fluctuation analysis (DFA), the long-range correlations in the time series of the hourly mean geoelectrical signals measured during 1995-1996 at the Tramutola station, located in one of the most seismically active areas of southern Italy. Scaling behaviour has been found in the time series of self-potentials. Characterizing the temporal fluctuations of the geoelectrical time series by means of the DFA scaling exponent, we recognize significant relationships with the earthquake activity of the area.