A research of mechanism of electromagnetic radiation associated with crustal activities

本研究的主要目的是阐明与地壳活动有关的电磁辐射特征，以寻求地震或火山喷发预报的新技术。分析了高知大学和美国斯坦福大学合作的ELF/VLF辐射计对自然电磁噪声的连续观测记录。S.一、首次研究了近5年来日本及其周边地区大地震和火山喷发与电磁噪声异常的关系。虽然没有观测到明显的电磁辐射，但有时观测到与有感地震地面运动同步的噪声级异常突变。不幸的是，很明显，在目前的记录中没有记录关于电磁波传播方向和特性的足够信息。 ...更多信息 由于记录容量的限制，辐射计的g系统。为了弥补这一缺陷，我们研制了一套大容量数字录音带ELF波连续记录系统。此外，我们还研制了一种非接触式的球形天线系统，利用大型不锈钢球来观测电场的三个分量，并在实验室、野外和浅海海底进行了初步的实验。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，并与观测结果进行了比较。特别是对电磁波在电离层中的传播机制及其随时间的变化规律提出了理论解释。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扼点上的澳大利亚北方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“科学研究资助”报告。少

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