Analyzing cross-correlations between earthquakes and geoelectrical extreme events, measured in a seismic area of Southern Italy

Correlations between geoelectrical extreme events and earthquakes have been investigated by means of the normalized wavelet cross-correlation function (NWCCF) and the cross-periodogram (CP). These methods allow to detect subtle forms of interdependence between sequences of events. In particular, we analyzed the correlation between the sequence of extreme events in geoelectrical signals, measured by the monitoring station Tito, located in a seismic area of southern Italy, and the series of earthquakes occurred in the same area during the 2001-2002. The NWCCF analysis highlights the presence of non-random cross-correlation between the series of geoelectrical anomalous values and the seismicity; the CP analysis reveals a co-fractal behavior between the self-potential extreme events and earthquakes, indicating that both sequences are subject to a common fractal modulation.