Long-term monitoring of self-potential and resistivity in Kyungju area where the largest earthquake occurred in Korea.

Long-term monitoring of self-potential (SP) and electrical resistivity was conducted to examine the correlation between seismic activity and changes of these geo-electrical components in the Kyeongju area where the largest earthquake occurred in Korea. Resistivity monitoring was carried out in 2018 and 2019 but the data was not continuos occasionally because of some accidents in the field. The longest monitoring of resistivity was about 120 days and the resistivity data were acquired in 5 minutes interval. The transmitted electrical source current has 1 Hz square periodic pattern and the received voltage for the source signal was obtained in the sampling rate 10 Hz. SP data were measured in 2019 in the sampling rate of 1 kHz. The monitored resistivity and SP data are being analyzed by some graphic charts which show the variations of resistivity and SP with earthquakes of which magnitude higher than 1.0 that occurred within 4 km of the measuring site. Unfortunately, no clear correlation between the monitored geo-electrical data and seismic activity has yet been confirmed.