Geomagnetic variation anomaly on Oshima Island is analyzed on the basis of observations during a period from 1966 to 1967. Short-period variations in the Z component are found to be affected seriously by variations in the D component on the eastern part of the island. Parkinson vectors are determined for six stations from a number of short-period geomagnetic events having a duration time of 30 minutes or so. Electric currents induced in the sea surrounding the island are calculated on the assumption that the conductivity distribution is proportional to the actual sea-depth. The magnetic field produced by such a current distribution is also obtained and compared with the observations. The presumption in the first report, i.e. that the spatial discrepancy of short-period variations observed on Oshima Island is caused by induced currents in the sea and also that the larger scale ""Central Japan Anomaly"" is superposed on such a locally-induced field, seems to be supported by the present analysis.|伊豆大島において1966年4月より翌年1月まで,携帯用フラックスゲイト型磁力計を用い,地磁気変化の同時観測を行なつた.その結果,短周期変化の鉛直成分が島内各所で著しい差を示すことが見出され,常北のプロファイルについての解析結果を前報で報告した.今回は観測期間後半の東西のプロファイルについてまとめてある.島の東側においては,西向きの磁場変化に伴なつて大きな下向きのZ成分が観測される.しかし島の西側では,東西方向の磁場変化に伴なうZ成分の異常は認められない.
雑誌名
東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo
巻
46
号
4
ページ
907 - 926
発行年
1968-10-31
ISSN
00408972
書誌レコードID
AN00162258
フォーマット
application/pdf
日本十進分類法
453
出版者
東京大学地震研究所
出版者別名
Earthquake Research Institute, University of Tokyo
45. Spatial Dependence of Short-period Geomagnetic Fluctuations on Oshima Island(2)
ji0464008.pdf
(1.04MB)
