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Observations of CD-seismic Electromagnetic Phenomena in VHF Band

VHF波段CD地震电磁现象的观测

基本信息

批准号：
14550367
负责人：
YOSHIDA Teruaki
金额：
$ 2.56万
依托单位：
Hiroshima City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

1)Observation systemIn our investigation, the observation of seismic electromagnetic phenomena have been conducted to solve these following subjects. 1.Does electromagnetic phenomena associated with EQ occur? 2.Does the EQ make the ionospheric layer reflect the FM broadcasting waves? To realize our observation, we have constructed the VHF band observation systems. The feature of our observation system is as followings.- Observation in FM broadcasting band : This band is hardly influenced by artificial or urban noises.- Dual Frequency Observation : To distinguish the seismic broadband phenomena from FM broadcasting waves, we have developed a novel dual frequency observation method in which the observation is made attwo different frequencies- Observation using digital FM tuner : This tuner has high frequency selectivity and stability, and thequantitative observation can be realized.(2)Observation results1.Observation of seismic electromagnetic phenomenaWe could observe the seismic phenom … More ena in Geiyo EQ (2001), Ibaraki-ken-oki EQ (2002), and Niigata-kenChuetsu EQ (2004). In these EQ, the broadband electromagnetic waves were observed. And it is found that these observed electromagnetic waves are generated from the seismic swing of the land near the observation site. Moreover, the other EM phenomenon detected in VHF band disappeared at the time of earthquake. Amplitude fluctuations of about 2 dB were observed since one day before the Geiyo EQ, then, the fluctuations disappeared at the occurrence of EQ.2.Observation of long-distance FM broadcasting propagationThe 77.1 MHz FM broadcasting wave from Sendai has been observed in Ibaraki observation site. From this observation, it is found that the FM broadcasting wave propagates in the tropospheric duct or on the geosphere. Our observation results show that the EQ hardly influence the ionospheric layer to reflect the FM broadcasting waves at the occurrence of EQ.(3)Improvement of observation system.Especially in the high electric field strength, the BPF should be inserted to reduce the intermodulation distortion. Less

1)观测系统在我们的研究中，对地震电磁现象的观测是为了解决以下问题。1.是否会出现与EQ相关的电磁现象？2. EQ是否使电离层反射FM广播波？为了实现我们的观测，我们建立了VHF波段的观测系统。我们的观测系统的特点如下。在调频广播波段观察：该波段几乎不受人工或城市噪音的影响。双频观察：为了区分地震宽带现象和调频广播波，我们提出了一种新的双频观测方法，即在两个不同的频率上进行观测--数字调频调谐器观测。数字调频调谐器具有很高的频率选择性和稳定性，可以实现定量观测。（2）观测结果1.地震电磁现象观测 ...更多信息 ena在Geiyo EQ（2001）、Ibaraki-ken-oki EQ（2002）和Niigata-ken Chuetsu EQ（2004）中。在这些EQ中，观察到宽带电磁波。并发现这些观测到的电磁波是由观测点附近陆地的地震摆动产生的。此外，在VHF波段检测到的其他电磁现象在地震发生时消失。从Geiyo EQ前一天开始观察到约2 dB的振幅波动，然后，在EQ发生时波动消失。2.远距离FM广播传播的观察来自仙台的77.1 MHz FM广播波已在茨木观测场观测到。从观测结果可以看出，调频广播波是在对流层波导中传播的，也可以在地圈上传播。我们的观测结果表明，在EQ发生时，EQ几乎不影响电离层对FM广播波的反射。（3）观测系统的改进，特别是在高场强下，应插入带通滤波器，以减小互调失真。少