Analysis of Non-Uniform Scaling Features in Ultra Low Frequency Geomagnetic Signals and Correlation with Seismicity

The scaling properties of the time dynamics of Ultra Low Frequency (ULF) geomagnetic data observed during 2000 and 2001 at Izu Peninsula in Japan are analyzed. The 50 Hz data and then resampled at 1 Hz were used for the analysis performed in the present study. On the base of the detrended fluctuation analysis (DFA), which is a powerful tool to detect and investigate time-scaling behavior in nonstationary signals, deviations from uniform power-law scaling were identified and quantified by means of an instability index. Our results point out to significantly high instability index in ULF geomagnetic data in relationship with the occurrence of large earthquakes and intense seismic clusters.