Time series analysis of self potential with various methods

This study was carried out with the help of four electrodes fixed in a selected area in Gülbahçe Village of Urla District of İzmir Province. It includes analysis of two years self- potential (SP) data recorded at specific time intervals between June 15, 2013, June 14, 2015 and November 24,2015, November 23,2017. In the study, evaluations of the data recorded in one of the two data loggers are presented. The methods used in these analyses are; "Detrended Fluctuation Analysis (DFA)" and "Power Spectrum". Self-potential data recorded every 10 minutes were analysed by calculating daily averages. Scaling exponent (alpha) of the self-potential data daily means for both date ranges was calculated with the polynomials degree of 1, 2, 3. Calculated scaling exponent is approximately 1,5. The beta spectral exponent values obtained by plotting the power spectra of the series with logarithmic scale for the date ranges of 15.06.2013-14.06.2015 and 24.11.2015-23.11.2017; 2,01 and 1,82 respectively. Using the relationship between the beta spectral exponent and alpha scaling factor, scaling factors were calculated. These are consistent with the values calculated by the EADA (1,505 and 1,41). From the analysis, it was seen that both of the self-potential time series had similar characteristics and characterized by a fractional Brownian motion. To examine the impact of earthquakes on self-potential data, power spectrum graphs were plotted using the hourly averages of self-potential data recorded at 10-minute intervals between January 27, 2017 and July 2, 2017, where seismic activity is intense. The spectral exponents were also calculated. In the region, including İzmir-Balıkesir Transfer Zone, inside the latitudes and longitudes between 37,81 degree – 39,03 degree and 26,12 degree – 27,97 degree the effect of the earthquakes on natural potential data is examined. The regions where the earthquakes which are thought to cause the increase of spectral exponent values (beta greater than or equal to three) were analysed, it was observed that the earthquakes in İzmir- Balıkesir Transfer Zone generally increased the spectral exponents according to the average.