著者

力武常次著

出版者

KTK学術図書出版

巻号頁・発行日

1984

著者

力武常次著

出版者

共立出版

巻号頁・発行日

1994

著者

力武 常次

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.42, no.4, pp.451-466, 1989-12-24 (Released:2010-03-11)

参考文献数

10

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Anomalous phenomena precursory to the 1891 Nobi earthquake of magnitude 8.0 are collected mostly based on the existing results of the enquiry investigation conducted soon after the earthquake. Precursor data amounting to 202 in number become available along with their precursor times. They are rumbling or detonation, anomalous animal behaviour, earthquake light, changes in underground water/hot springs and so on.It appears that the number of earthquake precursor tend to increase at about 100 days before the main shock. About 10 days preceding the shock, the increasing rate becomes much accelerated reaching a frequency peak having a precursor time of 1 day or so. Such a tendency of precursor appearance is much the same as that for the 1923 Kanto, 1944 Tonankai and 1978 Izu-Oshima Kinkai earthquakes although slight differences may be observed. The tendency that the number of precursor decreases as the distance between the epicenter and an observation spot increases is also confirmed.In light of these precursors detected by human sense in association with the Nobi earthquake as well as other large earthquakes in Japan, attention should be paid to precursors of this class along with geophysical precursors in future earthquakes.

著者

力武 常次 横山 泉 菱山 よね子

出版者

東京大学地震研究所

雑誌

東京大學地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.31, no.1, pp.19-31, 1953-04-25

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序報に於て日本に於ける地磁気短周期変化の異常を指摘したが,本報文に於ては世界各地の観測結果をもととゝして検討を加えた.1936年6月18日9時41分GMTの磁気嵐急始を解析して,ポテンシヤルと鉛直分力より,日本附近の変化磁場を地球外および地球内に原因を有する2部分に分離した.その結果地球内に起因する部分は第9図のような分布を示し,これが地表近くを流れる電流によって起ると考える時は,日本附近に渦状の電波系があることゝなり,通常の電磁感応の理論によっては,その分布を説明できず,地下に特殊の電気伝導度分布を考えねばならない.

著者

力武 常次 Yukutake Takesi Yamazaki Yoshio Sawada Munehisa Sasai Yoichi Hagiwara Yukio Kawada Kaoru Yoshino Toshio Shimomura Takafumi

出版者

東京大学地震研究所

雑誌

東京大学地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.44, no.3, pp.1335-1370, 1967-01

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Geomagnetic observations have been continued over the Matsushiro area since the middle of October, 1965. The results of observations during the period from February to April are reported. Five-day means of the total intensity observed at the centre of the seismic area revealed small fluctuations amounting to approximately ±2γ. As a result of magnetic dip surveys repeated with an interval of two months, it has turned out that there are localities where magnetic inclination changed more than 1'. Magnetic dip surveys were extended over the Toyono-Nakano-Susaka area in association with an unusual upheaval of land observed. Changes of the same amount as those in the Matsushiro area are indicated there. No clear relation between the geomagnetic changes and the seismic activities has been obtained.松代における全磁力の測定はその後も続けられ, 2月9日以来B測点では午前1時より2分間隔で6回自動的に測定するような装置に切りかえた.これは夜間の測定が昼間の測定よりよいデータを供するからである.この測定値と鹿野山の同時刻の値との差の5日平均の変動は±2γ程度のものであるが,これと地震活動との直接的な関係は明らかでない.