The MS6.2 earthquake occurred in Jishishan County,Gansu Province,on De-cember 18,2023.Within a 300 km radius of the epicenter,there were 9 fixed geo-electri-cal resistivity observation stations.This study preprocessed the geo-electric resistivity ob-servation data from 2 to 4 years before the earthquake,then analyzed the anomalous chan-ges before the earthquake after eliminating annual and trend changes.It showed a decli-ning 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 mag-nitudes of 4.9％(44 km),1.2％(164 km),and 0.6％(232 km)respectively.Earth-quakes occurred during the declining reversal period.These anomaly patterns are consist-ent 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 indi-cates that the changes in geo-electrical resistivity at these three stations are related to the MS6.2 earthquake in Jishishan.It was also found that there was no obvious pre-seismic a-nomaly 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 e-lectricity structure and fault distribution.
关键词
2023年积石山6.2级地震/地电阻率/年变化/异常变化
Key words
The 2023 Jishishan MS6.2 earthquake/Geo-electrical resistivity/Annual variation/Anomalous variations
维普
万方数据