Precise Observation of Earth Tides by Employing Superconducting Gravity Meters, Laser Extensometers and Laser Tiltmeters

1. 利用超导重力激光引力计对地球潮汐进行了精确观测。应用贝叶斯潮汐分析程序BAYtAP-G对重力和应变数据进行了潮汐分析。所得结果如下：(1)对安装在京都大学某观测室同一基地的两台超导重力仪进行对比，发现潮汐信号在幅值和相位上都非常一致，但长期漂移却不一致。这可能主要是由仪器噪声引起的。(2)对日本京都Amagase地壳运动观测站32个月的激光延伸仪潮汐应变资料进行检索，未发现与地震发生有关的异常变化。(3)将近基地区3个观测站（Amagase、Kishu和Rokko-Takao）的激光延伸仪观测到的潮汐应变与包含4种地球模型（1066A、G-B、海洋地幔和屏蔽地幔模型）计算的海洋潮汐载荷效应的理论预测值进行了比较。然而，在目前阶段，观测到的潮汐和预期的潮汐之间的差异太大，无法用于讨论确定哪种模型适合近畿地区。利用激光干涉测量装置研制并安装在京都神igamo地球物理观测站的水管反雨量计。自1992年3月以来，使用该仪器进行了地面倾斜度的精确测量。

1. Precise observation of earth tides by employing superconducting gravity me aser extensometers were carried out. Earth tides were analyzed by applying the Bayesian Tidal Analysis Program 'BAYtAP-G' to both gravity and strain data. Results obtained are as follows ;(1)Comparison of two superconducting gravity meters installed on the same base in an observation room at Kyoto University indicated that tidal signals were in excellent agreement in both amplitudes and in phases, but their long-term drifts were inconsistent with each other. This may be mainly due to instrumental noises.(2)A search of tidal strain data from laser extensometers at the Amagase Crustal Movement Observatory, Kyoto, during the period of 32 months revealed no evidence of anomalous changes related to the occurrence of earthquakes.(3)Tidal strains observed with laser extensometers at three observatories(Amagase, Kishu and Rokko-Takao)in Kinki district were compared with theoretically expected ones in which the ocean tidal loading effects calculated for four Earth's models(1066A, G-B, oceanic mantle and shielded mantle models)were included. At the present stage, however, differences between observed and expected tidal strains are too large to be used in discussion to determine what model is suitable for Kinki district.2. A water-tube ti-Itmeter using a laser interferometric device was developed and installed at the Kamigamo Geophysical Observatory, Kyoto. Precise measurement of ground-tilt using this instrument have been carried out since March, 1992.