A research of mechanism of electromagnetic radiation associated with crustal activities

与地壳活动相关的电磁辐射机制研究

基本信息

批准号：
02640308
负责人：
TABEI Takao
金额：
$ 1.34万
依托单位：
Kochi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02640308/
关键词：
Crustal Activities Electromagnetic Radiation ELF VLF Electromagnetic Noise 地震予知

项目摘要

Main purpose of this study is to clarify characteristics of electromagnetic radiation associated with earth's crustal activities in order to search for a new technique for prediction of earthquake or volcanic eruption. We analyzed continuous records of natural electromagnetic noises in ELF/VLF bands that had been obtained through cooperative observation using ELF/VLF Radiometer conducted by Kochi University and Stanford University, U. S. A., since 1985.We first investigated relationship between anomalous electromagnetic noises and major earthquakes and volcanic eruptions occurred in and around Japan during the past 5 years. Though clear precursory electromagnetic radiation was not detected, anomalous abrupt change of noise level was sometimes observed synchronously with the ground motion of felt earthquake. Unfortunately, it became clear that sufficient information about propagation direction and characteristics of the electromagnetic waves had not been recorded in the present recordin … More g system of the Radiometer because of the limit of recording capacity. To compensate for it we made a continuous recording system for ELF waves using Digital Audio Tape with a large recording capacity. Moreover, we developed a ball antenna system of noncontact type designed for observing three components of electric field using large stainless spheres and made preliminary experiments in a laboratory, field, and shallow sea bottom.Secondly, we executed many kinds of numerical simulations in analyses of background electromagnetic pulse waves in whistler and waveguide modes and then compared with the observed waves. Especially, theoretical interpretations on propagation mechanism of electromagnetic waves in the ionosphere and its time variation were advanced. Moreover, we investigated relationship between electromagnetic pulse wave observed at Kochi and lightening activity at northern Australia that is located at a geomagnetically conjugate point against Kochi.Finally, we summarized above research results as a Report of Research Project, Grant-in-Aid for Scientific Research. Less

本研究的主要目的是阐明与地壳活动相关的电磁辐射特征，以寻找预测地震或火山喷发的新技术。我们分析了已获得的 ELF/VLF 频段自然电磁噪声的连续记录。自1985年以来，高知大学和美国斯坦福大学利用ELF/VLF辐射计进行合作观测，首先研究了异常电磁噪声与电磁辐射之间的关系。过去5年里，日本及其周边地区发生了大地震和火山爆发，虽然没有检测到明确的前兆电磁辐射，但有时会观察到与有感地震的地面运动同步的异常突然变化的信息。由于记录容量的限制，有关电磁波的传播方向和特性的信息在辐射计的现有记录系统中尚未记录。为了弥补这一点，我们制作了连续记录系统。此外，我们还开发了一种非接触式球天线系统，用于使用大型不锈钢球观察电场的三个分量，并在实验室、现场和浅海底进行了初步实验。其次，我们对哨声模式和波导模式下的背景电磁脉冲波进行了多种数值模拟分析，并与观测波进行了比较，特别是对电离层中电磁波的传播机制及其时间进行了理论解释。此外，我们还研究了在高知观测到的电磁脉冲波与位于高知地磁共轭点的澳大利亚北部闪电活动之间的关系。最后，我们将上述研究结果总结为研究项目报告，Grant-减少科学研究援助。