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OBSERVATIONAL DATA ANALYSIS OF VERTICAL GEOELECTRIC FIELD IN TIANZHU AREA, GANSU PROVINCE

Combining with horizontal geoelectric field data in Hongshawan, Huangyangchuan and Songshan stations in Gansu province, the vertical geoelectric field data of three years observed in the three stations are studied. The results showed that:1??The obvious and stable annual periods of sinusoidal shape were found from vertical geoelectric field data in the three stations, but the value and the phases of an annual variation period are different.2??The impending anomalies before the earthquakes recorded by the vertical geoelectric field from Hongshawan station agreed with the earthquake occurrence in time and space. But whether the anomalies were caused by the earthquakes, a further research is needed.