{"created":"2021-03-01T06:51:50.524894+00:00","id":33098,"links":{},"metadata":{"_buckets":{"deposit":"91aa0b84-3482-44b2-bab2-01d9d7bb0075"},"_deposit":{"id":"33098","owner":"1","owners":[],"pid":{"revision_id":0,"type":"depid","value":"33098"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00033098","sets":["80:4535:4837:4838","9:504:4538:4839:4840"]},"author_link":["129086","129087","129084","129085"],"item_4_alternative_title_1":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"八ヶ岳地磁気観測所における地磁気・地電流から推定される中部日本下の電気伝導度構造"}]},"item_4_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"1980-03-31","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"3","bibliographicPageEnd":"501","bibliographicPageStart":"491","bibliographicVolumeNumber":"54","bibliographic_titles":[{"bibliographic_title":"東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo"}]}]},"item_4_description_13":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_description":"application/pdf","subitem_description_type":"Other"}]},"item_4_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"Impedance tensor elements were determined for periods between 20 and 240 min from the magnetic and telluric fields observed at the Yatsugatake Magnetic Observatory. The skew calculated from im- pedance tensor elements is much larger than 0.2, a critical value for two-dimensionality which implies that the structure is three-dimensional or the electric field observed at the Observatory is affected by local current channeling. It is found that such a channeling effect is expected in Z11 and Z21 whereas Z12 is unlikely to be affected by a local effect and can be used for inferring the regional conductivity structure. Three models of conductivity structure account relatively well for either the observed apparent resistivity or the observed phase, although the resolution is rather poor because of scatter in observed values. It is concluded that the conductivity structure beneath the central part of Japan is characterized by a conducting layer having a conductivity of 0.01 S/m and existing at a depth range of 30-50 to 100 km. This layer might reflect a small fraction of partial melt or conducting water.","subitem_description_type":"Abstract"},{"subitem_description":"八ヶ岳観測所では地電流2成分の観測を行っているが,電化線から漏れる電流が原因と思われるノイズが非常に大きく,誘導電流の観測はほぼ不可能となっている.しかし,1975年11月の終りから12月の初めにかけて電車が止まり,地電流の良好な記録が得られた.この時の記録を解析して,地磁気・地電流変化の特性を調べた.短周期変化の多い区間を4っ選び,それぞれから周期20分～240分のインピーダンステンソル要素(Z11,Z21,Z12,Z22)を計算して各周期に対して平均を求めた.もっと短い周期に対しては短周期ノイズのため正確には求まらない.インピーダンステンソル要素から求めたskewは,いずれの周期でも0.2よりかなり大きく,一次元および二次元的取り扱いをする場合には注意を要する.そこで,八ヶ岳観測所付近における誘導電流の特性として次のように考えた.磁場変化が北向きの時,Z11,Z21の位相はそれぞれ40°～50°となり,両者はほぼ等しい.これに対し,磁場が東西方向に変化する時は様子が異なる.Z12の位相はZ11,Z21とほぼ同じであるが，Z22の位相はこれらとかなり異なる.Z11,Z21,Z12の位相の共通性からみて,磁場に対して,40°～50°の位相が八ヶ岳観測所付近を流れる誘導電流の位相であろうと考えられる.そうすると,10°程度の位相をもつZ22が異常な誘導電流を表わしていることになる.この誘導電流がどういう原因によるものかは不明である.中部日本において日本列島がほぼ東西に延びていることを考えると,Z12はH-polarization caseのインピーダンスに対応する.このことから,Z12を用いて中部日本下の電気伝導度構造を推定することは妥当であろうと思われる.Z12から見かけ比抵抗が求まるが,この見かけ比抵抗とZ12の位相を説明するモデルを考えた.観測値を比較的よく説明するモデルに特徴的なことは,深さ30～100kmに0.01S/mの電気伝導度をもつ高伝導層が存在することである.この層の原因として,低率の部分溶融か,あるいは電気伝導度の高い水の存在が考えられる.","subitem_description_type":"Abstract"}]},"item_4_full_name_3":{"attribute_name":"著者別名","attribute_value_mlt":[{"nameIdentifiers":[{"nameIdentifier":"129086","nameIdentifierScheme":"WEKO"}],"names":[{"name":"本蔵, 義守"}]},{"nameIdentifiers":[{"nameIdentifier":"129087","nameIdentifierScheme":"WEKO"}],"names":[{"name":"小山, 茂"}]}]},"item_4_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.15083/0000033098","subitem_identifier_reg_type":"JaLC"}]},"item_4_publisher_20":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"東京大学地震研究所"}]},"item_4_source_id_10":{"attribute_name":"書誌レコードID","attribute_value_mlt":[{"subitem_source_identifier":"AN00162258","subitem_source_identifier_type":"NCID"}]},"item_4_source_id_8":{"attribute_name":"ISSN","attribute_value_mlt":[{"subitem_source_identifier":"00408972","subitem_source_identifier_type":"ISSN"}]},"item_4_subject_15":{"attribute_name":"日本十進分類法","attribute_value_mlt":[{"subitem_subject":"453","subitem_subject_scheme":"NDC"}]},"item_4_text_21":{"attribute_name":"出版者別名","attribute_value_mlt":[{"subitem_text_value":"Earthquake Research Institute, University of Tokyo"}]},"item_4_text_4":{"attribute_name":"著者所属","attribute_value_mlt":[{"subitem_text_value":"地震研究所"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Honkura, Yoshimori"}],"nameIdentifiers":[{"nameIdentifier":"129084","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Koyama, Shigeru"}],"nameIdentifiers":[{"nameIdentifier":"129085","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2017-06-26"}],"displaytype":"detail","filename":"ji0543005.pdf","filesize":[{"value":"632.8 kB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"ji0543005.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/33098/files/ji0543005.pdf"},"version_id":"cc0a691c-4082-46b6-a5d7-6947b164e6d4"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_title":"Electrical Conductivity Structure beneath the Central Part of Japan as Inferred from Magnetotelluric Fields at the Yatsugatake Magnetic Observatory","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Electrical Conductivity Structure beneath the Central Part of Japan as Inferred from Magnetotelluric Fields at the Yatsugatake Magnetic Observatory","subitem_title_language":"en"}]},"item_type_id":"4","owner":"1","path":["4838","4840"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2008-05-30"},"publish_date":"2008-05-30","publish_status":"0","recid":"33098","relation_version_is_last":true,"title":["Electrical Conductivity Structure beneath the Central Part of Japan as Inferred from Magnetotelluric Fields at the Yatsugatake Magnetic Observatory"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2022-12-19T04:08:47.099524+00:00"}