Elimination of annual variation of resistivity at Yangyuan station in Hebei Province and its seismic response

Based on the observation data of ground resistivity at Yangyuan seismic station from 1980 to 2017，it is found that the measured value of ground resistivity at Yangyuan seismic station has clear “V” type annual variation characteristics of high values in winter and low values in summer. After eliminating the annual variation information with the appropriate Fourier sliding method，the change of normal background and anomalous characteristics is more remarkable. The relationship between the anomalies and major earthquakes，such as the Fengzhen M5.8 earthquake in 1980，the Datong M6.2 earthquake in 1988 and the Baotou M6.4 earthquake in 1996，the Zhangbei M6.2 earthquake in 1998 and the Zhuolu M4.8 earthquake in 2014 around Yangyuan station，can be identified in the corrected resistivity curves. The indexes of anomalous variation characteristics，duration and deviation amplitude have high reliability，which can provide reliable reference for the study and judgment of seismicity in the border area of Shanxi，Hebei and Mongolia.