抄録
We describe the superconducting gravimeter (GWR #11) observation system at Kakioka and present initial results. The observed raw gravity data contain the tidal signal, stepwise changes, drift, etc. The tidal gravity values were examined by the tidal analysis program, BAYTAP-G. A calibration factor for the GWR #11 gravimeter of 51.2486 μGal/volt was determined by comparison between the observed M2 gravimetric factor and the theoretically calculated one. The other gravimetric factors and phases observed are coincident with theoretically calculated ones to within 100 nGals. Stepwise changes occurred due to large, nearby earthquakes and a kind of deformation mechanism of the instrument and/or a newly constructed U shaped concrete pillar on which the gravimeter is supported. Long term drift can be represented by the sum of two exponential curves with two different decay constants, 35 days and 609 days, indicating that two types of creep processes may be occurring in the gravimeter or in the supportive pillar. The gravimetric factor of polar motion was determined as 1.35±0.20 using the gravity residuals together with the instantaneous rotation axis position data from the IERS network. This value suggests that changes in gravity due to polar motion are probably affected by the atmosphere and mantle anelasticity.
