Stusy of dynamics of the Earth's deep interior based on the global network of superconducting gravimeters

基于全球超导重力仪网络的地球深部动力学研究

• 批准号: 07304035
• 负责人: SEGAWA Jiro
• 金额: $ 8.77万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07304035/
• 关键词: superconducting gravimeter; dynamics of the earth's deep interior; GGP; Syowa station; Earth tides; pole tides; free oscillations of the earth; 海洋潮汐; TOPEX; POSEIDON; 極運動; 地球システム科学

1. It was agreed that the observing period of GGP (Global Geodynamics Project) should be from July 1997 to June 2003. Accordingly, final adjustments of the instruments were done. The gravity data from the Japanese stations are already available for exchange, and were used for earth tide analysis. As a result, it was found that common signals presumably originating from the atmosphere exist in plural gravity residuals. This demonstrate that there is much to be studied for estimating the atmospheric contribution on the gravity.2. A new superconducting gravimeter was installed in Australia by National Astronomical Observatory. Also, colleagues at Kyoto University are planning to move one of the two superconducting gravimeters installed at Kyoto to a new site in Indonesia within 1997. These new gravity stations, together with the existing stations in the Syowa station, Antarctica and in the Japan mainland, form a large scale network from the west Pacific to Antarctica. In addition, these new stations will contribute much to the global coverage of superconducting gravimeters, which is essential to the GGP network.3. Gravity change associated with the polar motion of the Earth (pole tide) was observed from the superconducting gravimeter data acquired at Syowa station, Antarctica. The period and the attenuation parameter of the Chandler motion were estimated with good precision. However, there were discrepancies between the observed values of the delta-factor and the phase and the theoretical predictions. This was attributed to the effect of the atmosphere and the ocean.4. Spectral analysis of the superconducting gravimeter data from Syowa station, Antarctica revealed that there exist some power corresponding to the elastic normal modes of the Earth even without any large earthquakes. This implies that free oscillations of the Earth are continuously excited. The possible sources of excitation include the global atmospheric changes.

1.会议商定，全球地球动力学计划（GGP）的观测期为1997年7月至2003年6月。因此，对仪器进行了最后调整。来自日本台站的重力数据已可供交换，并用于固体潮分析。结果发现，推测源自大气的共同信号存在于多个重力残差中。这表明，在估算大气对重力场的贡献方面还有许多工作要做.澳大利亚国家天文台安装了一台新的超导重力仪。此外，京都大学的同事们正计划在1997年内将安装在京都的两台超导重力仪中的一台搬到印度尼西亚的一个新地点。这些新的重力站，加上昭和站、南极洲和日本大陆的现有重力站，构成了从西太平洋到南极洲的大规模重力站网。此外，这些新站将大大有助于超导重力仪的全球覆盖，这对GGP网络至关重要。利用南极昭和站超导重力仪观测资料，观测到了与地球极移（极潮）有关的重力变化。对钱德勒运动的周期和衰减参数进行了精确的估计。然而，δ因子和相位的观测值与理论预测值之间存在差异。这是由于大气和海洋的影响.对南极昭和站超导重力仪观测数据的谱分析表明，即使没有大地震，也存在着与地球弹性简正模相对应的功率。这意味着地球的自由振荡是不断激发的。可能的激发源包括全球大气变化。

项目成果

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