Abstract: The M_S6.2 earthquake occurred in Jishishan County, Gansu Province, on December 18, 2023. Within a 300 km radius of the epicenter, there were 9 fixed geo-electrical resistivity observation stations. This study preprocessed the geo-electric resistivity observation data from 2 to 4 years before the earthquake, then analyzed the anomalous changes before the earthquake after eliminating annual and trend changes. It showed a declining trend in ground resistivity and a reduction in the annual variation amplitude before the earthquake at Linxia Station, Dingxi Station, and Tongwei Station, with decreasing magnitudes of 4.9% (44 km), 1.2% (164 km), and 0.6% (232 km) respectively. Earthquakes occurred during the declining reversal period. These anomaly patterns are consistent with statistical results from a large number of earthquake cases. Moreover, the closer the distance to the epicenter, the greater the magnitude of the anomaly change. This indicates that the changes in geo-electrical resistivity at these three stations are related to the M_S6.2 earthquake in Jishishan. It was also found that there was no obvious pre-seismic anomaly at the Jinyintan seismic station, which is 219 km away from the epicenter of the earthquake. Further analysis will be conducted in conjunction with the station’s actual electricity structure and fault distribution.

Key words: The 2023 Jishishan M_S6.2 earthquake, Geo-electrical resistivity, Annual variation, Anomalous variations