Detection of the oscillations of Earth's core by a collaboration observation with superconducting gravimeters and laser strain meters-Comparison between the Kamioka site and Matsushiro site-

通过超导重力仪和激光应变仪的协作观测来检测地核的振动～神冈遗址与松代遗址的比较～

基本信息

批准号：
16340134
负责人：
SATO Tadahiro
金额：
$ 10.69万
依托单位：
National Astronomical Observatory
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

This research project was planed to detect weak normal mode signals from the Earth's core based on the observations with two superconducting gravimeters (SGs) at Kamioka and Matsushiro and by a comparison between the SG and laser strain meters set at Kamioka. H. Ikeda of the Tsukuba University and Severine Rosat of JSPS fellow did join to this project as the cooperative researchers though the term of the project.We have done the followings ;1.Developing a new non-linear analysis method for the normal mode analysis, which can treat both the frequency and Q-value of normal modes as unknown parameters,2.Analysis of the SG records mainly of the Sumatra-Andaman earthquake (Mw=9.0-9.3), which were obtained from the world wide SG network including Kamioka, Matsushiro and the Syowa Station in Antarctica,3.Improving the quality of the laser strain meter and the analysis of the records of the Sumatra-Andaman earthquake,4.Improving the estimation accuracy of gravity effect of the regional atmosph … More eric air mass changes,5.Investigating the accuracy of modern global ocean tide models, which are used in the correction for the ocean tides, and also studying the non-tidal sea surface height variations by comparing some model computation results with the actual data obtained from the ocean bottom pressure measurements in Off-Sanriku,6.Improving the calibration accuracy of the scale factor of SG by using an absolute gravimeter.In December 26th 2004, two months later when the SG was newly installed at Kamioka, the Sumatra-Andaman earthquake occurred. The fundamental radial mode _oS_o, which consists of a global deformation of the Earth with changes in its circumference, has been strongly excited by this event and its time decay has been observed till the occurrence of the second Sumatra event in March 28th 2005 at many of SG sites. A notable result obtained by this research project is; we have succeeded to reveal that the _oS_o mode shows a geographical amplitude distribution depending on not only the latitude but also on the longitude, which may reflect a large scale lateral inhomogeneity in the Earth's structure. The observed geographical pattern is consistent with the model prediction based on a 3-D seismic tomography model.Based on the two SG data sets for the Sumatra-Andaman event, which were obtained at Strasbourg (France) and Canberra (Australia) and using the new analysis method developed by this project, we have tried to find out such weak core signals as the Slichter triplets and the core undertones. Although we found some peaks to be closely related to these modes, the analysis results have not revealed such inner core signals yet, because some spectrum peaks fond are not observed commonly at these two sites.The effect of tsunami waves excited by the Sumatra event was also observed by several instruments set at the Syowa Station including the SG. We have compared the predicted tsunami effects with those observed from the SG and SST-1. Improvement of the accuracy of the bathymetry around the Syowa station is essential to improving the comparison accuracy between the observations and predictions. Less

该研究项目计划根据Kamioka和Matsushiro的两个超导重量表（SGS）的观测值，并通过比较Kamioka设置的SG和激光菌株仪之间的比较，以检测地球核心的弱正常模式信号。 Tsukuba大学和JSP的H. （MW = 9.0-9.3），是从全球SG网络中获得的，包括Kamioka，Matsushiro和南极洲的Syowa站，3。3. Improve激光应变表的质量以及对Sumatra-andAnaman Earthqeartqeake的记录的分析，4. IMPROVE IMPROVE SUMATRA-andAman the Reciality Alterial Apperional Massion Massial Massial Massies Airs Massies Airs Massie Airs Massies Airs Massies Airs Massie Airs Massie Airs Massiq airs Masties 5的准确性。研究了现代全球潮汐模型的准确性，这些模型用于海洋潮汐的校正，并通过将某些模型计算结果与从山anriku的海底压力测量获得的实际数据进行比较，研究了非潮汐海面高度变化，6。通过使用绝对颗粒仪来提高SG量表因子的校准精度。在2004年12月26日，两个月后，当SG新安装在Kamioka时，发生了Sumatra-andAman地震。基本的径向模式_OS_O由地球的全球变形随着其圆周的变化而组成，这一事件一直很兴奋，并且已经观察到时间衰减，直到2005年3月28日在许多SG地点发生的第二次苏门答腊事件发生。该研究项目获得的一个值得注意的结果是；我们成功地揭示了_os_o模式不仅取决于纬度，而且还取决于经度，这可能反映了地球结构中大规模的横向不均匀性。观察到的地理模式与基于3-D地震层析成像模型的模型预测一致。基于在苏门答腊和苏门答腊 - - 安达事件的两个SG数据集上获得的，该模型是在Strasbourg（France）和澳大利亚（澳大利亚）（澳大利亚）获得的，并使用该项目开发的新分析方法，我们试图找到如此弱小的核心信号，例如诸如Spele Core和Core Core and the Core Core and the Core and the Core and the Core and the Core and the Core。尽管我们发现一些与这些模式密切相关的峰，但分析结果尚未揭示出这种内部核心信号，因为在这两个地点上尚未观察到一些频谱峰。我们已经将预测的海啸效应与从SG和SST-1观察到的效应进行了比较。提高SYOWA站周围测深的精度对于提高观测值和预测之间的比较准确性至关重要。较少的