165 research outputs found

    Low frequency seismogenic electromagnetic emissions as precursors to earthquakes and volcanic eruptions in Japan

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    A multipoint network was constructed in the Tokyo area for earthquake prediction using seismogenic electromagnetic emissions. The network consists of eight observation points within 50 km of each other.Each point has a digital direction-finding detector with two loop sensors tuned to 82 kHz. The output signals of the receivers are added into a digital vector composition circuit to obtain the direction angle of the source point,and this signal is telemetered to the central computer.To protect from false alarms caused by local man-made noise interference,the warning is announced only when there is a high cross-correlation between almost all detectors pointing to one small area. The mechanism of these earthquake precursors can be explained as electromagnetic emissions from the rocks around the focus when they are crushed completely by the distortion pressure. These emissions propagate along the fault plane as an EM surface wave mode and radiate from the slit antenna formed by the intersection of the fault plane and ground surface.In the last five years, we have detected impulsive noise bursts of seismogenic emissions at 82 kHz, 1.525 kHz, and 36 Hz using our multipoint detection network around the Tokyo region and Izu peninsula. This system has recorded EM signals prior to the following events: volcanic eruptions on November 15 and 2 1, 1986 at Mt. Mihara on Ohshima Island, and on July 12, 1989 in Itoh Bay in the Izu peninsula region, and also a minor earthquake on October 14, 1989 at Ohshima Island

    LF seismogenic emissions and its application on the earthquake prediction

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    The authors are building a multi-point network system for the prediction of earthquake epicenter location by means of the seismogenic emission phenomena around Tokyo area. The network system consists of eight observation points with 50 km from each other and at each point a new digital type direction finding detector is set up with two loop sensors tuned to 82kHz. The output signals of the receivers are added into the digital vector composition circuit to obtain the direction angle of the source point,and this signal is transmitted to the center computer through a telemeter line. In order to protect from local man-made noise interferences,the warning is only anounced when the computation results of the center computer pointed one small area with high cross-corelation values for area from between all points.The source mechanism of emission related to precursors of earthquakes can be explained as electtromagnetic emissions for the rocks around the focus when they are crushed completely by the distortion pressure.And these emission energies are propagated in the ground along the boun-dary surface of the fault as a surface wave mode and radiated from the slit antenna which consists of the boundary at the ground surface of the fault.The authors will present the computer flow and try to explain the source mechanism of these emission in this paper.利用は著作権の範囲内に限られ

    Power Line Radiation over Eastern Asia Observed by the Satellite OHZORA

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    Statistically improved results of power line radiation (PLR) over Eastern Asia observed at 50 and 60 Hz are described in this paper. A total number of 150 orbits, which had been observed from June 1984 to January 1986, by the Japanese scientific satellite OHZORA, are used to detect PLR over Eastern Asia around the Japanese Islands. Depending on the increase in the number of data points, the statistical characteristics of the background noise can be precisely determined by using the improved technique compared with the initial analysis. Statistically reasonable data points are detected as PLR based on the +3σ criterion, where σ is the standard deviation of the background noise. Therefore, the statistical reliability for rejecting the background noise is 99.85%. Then, these detected data are applied to the cause-and-effect test. When the statistically detected data points are placed on the map of Eastern Asia, the points cover Eastern Japan and the east coast of China for 50 Hz, and they cover Western Japan for 60 Hz. The maps of the detection ratios and those of the average field strengths indicate the positive correlation with the ground maps of the electric power generation at 50 and 60 Hz. The positive correlation is more clearly seen at 50 Hz since the background noise is somewhat weaker than that at 60 Hz. This close relationship between the satellite observation and the electric power generation suggests that the detection of PLR is not caused by chance, and that PLR penetrates into the ionosphere and propagates approximately just upward. The decrease of field strength with altitude can be interpreted as the gradual decrease of the refractive index from to 700 km. Therefore, the detection ratio and the average field strength with respect to the satellite altitude suggest PLR propagating from the bottom of the ionosphere. According to these observational results, it is concluded that PLR in Eastern Asia is high above the high electric power generating regions over Japan and China, and that the satellite observation is capable of estimating PLR field below the ionosphere. These results are the first direct indication that the PLR field is enhanced over the high electric power generation region, and is penetrating into the ionosphere

    地震に伴う電磁波放射現象と予知に関する研究

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    This paper presents the observation results of electromagnetic emissions which appear before the first shock of earthquakes as the precursor, and include to examine the source mechanism of this phenomena.Also this paper shows one of the example of successful result of the earthquakes and its epicenter point prediction experiment by means of the multipoint direction finding networks which set up arround Tokyo area since 1983.利用は著作権の範囲内に限られ

    Radio Echo Sounding of Antarctic Ice

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    ヒョウカンセツ ジョウ ノ デンパ デンパン トクセイ

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    1.目的 万年雪,高圧気泡入氷からできた氷冠域において,雪氷の高周波誘電特性雪,表面の電波の反射吸収特性,比抵抗等を測定することにより,極地方の氷冠内における電波伝播特性の解析,氷冠上にて使用するアンテナの設計,通信回線の設計等のための資料を得ることを目的とし,1.5,10,100,250,300,400,3000Mcの各周波数毎に,(1)容量置換法,レッヘル線により,誘電率,誘電体損(tanδ)を,(2)ハイトパターン法により反射,吸収係数を,コーラウシュブリッジにより比抵抗を測定し,数種のアンテナにより通信を行ない電界強度を測定した.また気温逆転層による300,3000Mcのフェーディング特性,万年雪にまい没したアンテナと空間のアンテナとのインピーダンス,指向性パターン等も測定した.2.結果 実測の結果,万年雪および氷冠氷の比誘電率の値は非常に小さく,周波数の増加,密度の減少とともに減少する.誘電体正切特性の値も非常に小さく,周波数の増加とともに激減する.反射係数もHF帯では小さく,周波数の増加とともに増加する,従って氷冠の雪氷上で使用するアンテナは表面の雪の比誘電率が1に非常に近いので,雪面上に直接導線を置くだけの非常に簡単なアンテナで,ほぼ自由空間とみなし得る輻射が得られることが解り,秋春の大陸旅行において実証することができた.なお,測定に使用した機器は昭和基地にて製作したため帰国後検定中であり,期日の都合で今回は現在までに得られた較正データのみ中間報告として発表する.海氷上の電波伝播はVHF以下の周波数帯では大略海水面と同じ特性を示し,UHF以上はその表面の状態(氷,雪)の影響が大きい.なお偏波面は氷冠上が水平,海氷上は垂直が良いようであった

    エットウ キカンチュウ ノ デンキ カンケイ ホウコク

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    第3次越冬においては,(1)1年無保守状態のまま放置された機器の回復と,(2)空輸のため燃料節約を必要とし,(3)多くの観測機械が設置されるため,電圧変動,三相発電機の相間バランス,各相の力率変動を極力防止する必要があった.そのため各部門の使用電力量,使用時間を規制し送電系統を並列に改めて負荷の調整を行なった結果,各棟約5KWの負荷時の入力端子間電圧降下は約0.5V以内に改められた.20KVA発電機の燃費は上記の規制に隊員の協力を得て予想以上の節約ができた.運転時間は1号が5479時間,2号は3116時間で非常に良好に保守され機器の故障は皆無,送電停止時間は計11分30秒,発電機関係の補用品も充分量保有している.発電量は年平均1日134.2KVA,燃費は80.7lであった.小型発動発電機類も飛雪に対する注意と燃料内の氷晶除去に留意すれば低温下でも容易に運転できた.450WDC発電機が雪上車のAPUとしても最も使用され,特に-40℃以下の雪上車の起動に際しあらかじめ本機でバッテリーに30Aの充電電流を約5分間流すことにより,予熱の必要なく安全に一気に起動できた.その他フィールド用として1KVA,350WAC発電機も使用した.バッテリーは電解液の比重低下したものが液凍結によって破損したものがある.高比重(1.35/-30℃以上)に保つことが必要である.電気関係の諸機器は非常に良好な状態に保たれ,適切な保守によって相当長期間の使用に耐え得る

    1993年国際チューリッヒEMCシンポジウムの概要

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    エットウ キカンチュウ ノ ネンリョウ カンケイ ホウコク

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    第3次越冬は空輸によったため,越冬開始に当り226本の発電機用軽油の消費規正を行い,予備46本とし,年間使用量を180本と決め,各部門の電力使用量,時間等を規正して1日当り使用量を夏85l,春秋95l,冬110lと決めたが,隊員の協力により夏平均76.5l,冬平均83.1l,年平均80.7l,年間使用量157本の実績であった.雪上車用ガソリンの低温対策としては旅行出発前に全燃料中に含まれる氷晶を厚手ナイロン地でフィルトし,飛雪の混入を防止して解決した.ソ連ガソリンに比較して日本製ガソリンには氷晶の混入がはるかに多い
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