神岡鉱山における繰り返し絶対重力測定と重力季節変化

摘要

Since July 2005, we have repeatedly carried out absolute gravity measurements at Kamiokamine, Gifu, in the deep tunnel about 1 km below the ground surface. A superconducting gravimeterwas already installed in the same place. The secular changes of gravity have been investigatedusing the absolute and the superconducting gravimeters. We have detected gravity changesof several tens of μ gals (1 μ gal = 10~(-8)ms~(-2)).The gravity changes detected by the absolutegravimeter show good agreement with gravity residuals in the superconducting gravimeter data.The gravity changes strongly suggest seasonal ones due to hydrological effects, especially to thesnow effect.