POSSIBLE ANOMALOUS CHANGES OF GEOMAGNETIC TRANSFER FUNCTIONS AT HEZE STATION RELATED TO THE M5.9 HEZE EARTHQUAKE OF NOV. 7, 1983

The dispersed Fourier spectra of 198 geomagnetic short period variations at Heze during two years and a half are obtained by fast Fourier transform. Then, the transfer functions of these geomagnetic events are calculated with the data of dispersed Fourier spectra by the method of least squares. It is found out from these results that the anomalous changes of the transfer functions before and after the M 5.9 Heze earthquake of Nov. 1983 are definite, though the transfer functions suffer somewhat from influences of calculating errors. It is suggested that the anomalous changes of transfer functions may be precursory changes related to the occurrence of the earthquake by statistical tests and correlation analyses between transfer functions and some disturbance factors.