| Summary: | application/pdf An anomalous feature of the Z component of the Sq in the central part of Japan is pointed out. From geomagnetic observations at Kakioka and Aburatsubo was ascertained the fact that the maximum decrease of the Z component of the Sq occurs about an hour earlier in central Japan than at any other observatory in the Far East. On analysing the Sq during the Second International Polar Year, it is found that the aforementioned anomaly of Sq is most likely caused by the anomalously small internal origin part which would suggest low electrical conductivity under Japan. It is also suggested that the weak conducting region penetrates as deep as 700km or so there. 地磁気日変化の鉛直分力は柿岡に於いて,いちじるしい異常を呈することを指摘し,油壺,女満別および阿蘇の日変化を整理して,この異常が日本中部に特有なものであることを明らかにした.すなわち柿岡および油壺においては,日変化鉛直分力の最小が他の極東地方の観測所にくらべて1～2時間早く起るのである.この異常の原因を調べるために,第二回極年の資料を整理したところ,日本中部に於ては日変化のうち地球内に原因をもつ部分が地球の平均状態に対して期待されるものより小さいことがわかつた.このことは日本の地下数百粁の探さの部分の電気伝導度が小さいことを示唆する. departmental bulletin paper
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