Study on Earth Crust Anomaly Through Sound Signal Processing of ELF Band Electromagnetic-Wave Precursor

1.在17赫兹和223赫兹的ELF频段，研制的每根赫兹次PT量级的高灵敏度接收器探测到了前震和火山喷发的异常电磁波辐射。根据辐射方式将辐射分为几类或几种类型：(1)日本中部伊藤市发生火山群时，辐射的幅度出现了剧烈的变化，如放电。辐射机制是由于深熔岩或岩浆中的脱气氧化产生的电子电荷从地表释放到空气中所致。2000年8月18日，三宅岛火山喷发时也出现了同样的辐射。(2)在同一次三宅岛火山喷发过程中，当岛屿之间的距离为每天10厘米时，出现了壮观的辐射现象，GPS和地震仪也同时观测到了这一现象。辐射被认为是由于电流补偿了因机械压力而扭曲的地壳电导率和介电常数的电性变化。(3)2001年4-9月静冈中部地震链观察到辐射水平平稳上升。近年来，该地区不断遭受海陆板块之间的板块滑动。从辐射行为的角度对观测到的异常进行了估算，认为这是平板间摩擦热能激发的自由电子可能产生的热激荡噪声。为了提取壮观的前兆成分和/或消除接收到的噪声，成功地将声音信号处理方法和电磁波分析应用于所获得的数据。

1. Anomalous electromagnetic-wave radiation has been detected in advance earthquakes and volcanic eruption by the developed high sensitive receiver of order of sub-pT per root Hertz at the ELF band of 17Hz and 223Hz2. The radiation was classified into several categories or patterns according to their way of radiation.(1)The pattern at the occasion of volcanic swarm experienced at Itoh-city, Central Japan, was appearing with severe variation in the amplitude like a discharge. The radiation mechanism is conceived due to discharge from the earth surface to the air due to electron charges by oxidization of degas which is originated from the deep melted rock or magma. The same radiation was appeared at the Miyake island's volcanic eruption on August18th of 2000.(2) The spectacular radiation was obtained when the diastrophism of islands in the course of the same Miyake volcanic eruption, the distance between Niijima and Kouzu islands separated 10cm a day, the phenomenon was also observed by GPS and seismometer simultaneously. The radiation is thought due to current compensating the change in electrical property as conductivity and dielectric constant of the earth crust distorted by mechanical pressure.(3) The smoothed increase in the radiation level was observed at the chain of earthquakes in the central Shizuoka in April to September 2001. The area was continuously subjected to the plate slip between sea and land plates in recent years. The observed anomalies were estimated from the way of radiation behavior as the possible thermal agitation noise of free electrons excited by the friction heat energy between the plates.3. Sound signal processing methods and electromagnetic-wave analysis were successfully applied to the obtained data in order to extract the spectacular precursor components and/or to eliminate the received noises.