ANALYSIS OF THE RELATIVE VARIATION OF GRAVITY DATA IN THE GRAVITY SURVEY FOR EARTHQUAKE PREDICTION

In this paper a systematical discussion and some necessary calcullations have been made for several factors influencing the relative variation of gravity field. The results have shown. that after eliminating the influences of the calibration of instrument value and temperature, the relative variation of gravety ismainly due to deep mass movement, and the second reason may, be the veriatation of underground water level of the order of less than 50 u al.As an example the data of the Tangshan earthquake are calculated and analysed.