{"created":"2021-03-01T06:51:39.658764+00:00","id":32934,"links":{},"metadata":{"_buckets":{"deposit":"06823e34-22f5-4720-9049-014b7afb15e3"},"_deposit":{"id":"32934","owner":"1","owners":[],"pid":{"revision_id":0,"type":"depid","value":"32934"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00032934","sets":["80:4535:4797:4798","9:504:4538:4799:4800"]},"author_link":["128410","128409"],"item_4_alternative_title_1":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"35. 線形ピエゾ磁気変化の面積分による表現"}]},"item_4_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"1984-03-31","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"4","bibliographicPageEnd":"785","bibliographicPageStart":"763","bibliographicVolumeNumber":"58","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":"A representation theorem of the linear piezomagnetic field is formulated for a homogeneous and isotropic magneto-elastic material. The tectonomagnetic field is given by surface integrals of the displacement and its normal derivatives over the strained body. This is a corrected version of previous results (SASAI 1980). Applying the theorem to a medium including a dislocation surface within it, we find that the dislocation surface behaves as a magnetic sheet. For a special type of dislocations where all the stress components are continuous across the dislocation surface, the magnetic sheet is simply a double layer, of which moment is given by the inner product of the displacement discontinuity and the magnetization vector. The seismomagnetic moment thus defined is useful to intuitively presume coseismic magnetic changes, which is demonstrated for the seismomagnetic effect accompanying the 1946 Nankaido Earthquake of M8.1. With the aid of potential theory, the tectonomagnetic field at the Earth's surface is found to contain some information of the strain field at the observation site. This gives a measure of sensitivity of the magnetic measurement as a strain sensor, which amounts to roughly 10μ-strain per nT in a strongly magnetized region. The use of representation theorem greatly reduces efforts of tectonomagnetic calculations in comparison with the traditional dipole force law. It is exemplified by actually applying the theorem to the Mogi model.","subitem_description_type":"Abstract"},{"subitem_description":"筆者(1980)は一様均質な磁気弾性体が歪んでいる時,ピエゾ磁気効果で生ずる磁場を,その物体の表面変位と垂直微分の面積分で表現する式を得た.この定式化の一部に誤りがあったので訂正し,あわせて前報より多少ふみこんだ考察を行なった.筆者とは独立に,同じような定式化がBONAFEDE and SABADINI(1980)によって行なわれ,一般の異方性磁気弾性体の作る磁場のベクトル・ポテンシァルについての表現定理が得られている.筆者の方法では,磁化を磁場の源泉とし,スカラーポテソシァルで場を記述する.STACEY(1964)以来の仮定に従って,磁歪と二次的誘導磁化を無視し,帯磁率と硬い残留磁化の応力変化を同等に扱った.磁場についてのガウスの法則と弾性体の静的つりあいの式とを,磁気弾性体の構成法則(線形ピエゾ磁気公式とフックの法則)で結合して,基礎方程式を導く.これは変位場で表わされた源泉項を持つポアソン方程式になる.体積分項を含むその解をグリーンの公式を用いて変形して,上記の表現定理を得た.この式をくい違い面を含む物体に適用すると,くい違い面の位置にも磁気的一重層と二重層が現われる.特にくい違い面上で全ての応力成分が連続な場合(ヴォルテラ型くい違い等はこれに当る),二重層のみが残り,その磁気モーメントはくい違い量と磁化ベクトルの内積で与えられる.この量は地震地磁気効果の大きさを表わすのに最適なので,これを地震地磁気モーメントと呼ぶことにする.地震地磁気モーメントの考えを用いると,地震に伴う地磁気変化の様相を定性的に理解するのが容易になる.一例として有名な南海道地震に伴った地磁気変化(KATO and UTASHIRO, 1949)を考察し,観測された通り,偏角の東偏が期待されることを示した.表現定理の形から.磁気ポテンシァルと変位,磁場と歪の対応関係が予想される.ポテンシァル論の定理を用いて,地表での磁場変化がその点の歪変化のある成分に比例した項を含むことを示した.大体,10μ-strain程度の歪に対して,1nTの地磁気変化が対応する.しかし実際の磁場変化にはそれ以外の項の寄与が大きく,磁場観測が直ちに観測点の歪だけを測っているとはいえない.表現定理を茂木モデル(MOGI 1958)に適用して,これに伴う地磁気変化を求めた.結果は従来得られていた体積分による解(SASAI 1979)と全く一致するが,本稿の方法による方が著しく計算量を節約できる.実際の地球では地殻の上部しか帯磁していないため,地震地磁気モーメントの考えをそのまま適用できない場合も多い.しかし簡単な2次元断層モデルでは,非磁性の断層面上にも,見掛上地震地磁気モーメントと等しい磁気二重層が現われる.最後に本稿の方法が境界要素法と原理的に同じ考えに基づいていること,更に複雑な形状の磁気弾性体による磁場を数値的に求めるのに,境界要素法が有効である点にも触れた.","subitem_description_type":"Abstract"}]},"item_4_full_name_3":{"attribute_name":"著者別名","attribute_value_mlt":[{"nameIdentifiers":[{"nameIdentifier":"128410","nameIdentifierScheme":"WEKO"}],"names":[{"name":"笹井, 洋一"}]}]},"item_4_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.15083/0000032934","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":"Earthquake Research Institute"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Sasai, Yoichi"}],"nameIdentifiers":[{"nameIdentifier":"128409","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":"ji0584002.pdf","filesize":[{"value":"1.2 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"ji0584002.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/32934/files/ji0584002.pdf"},"version_id":"00004aad-aef9-4e68-b673-0f6c7c8f7650"}]},"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":"35. A Surface Integral Representation of the Tectonomagnetic Field Based on the Linear Piezomagnetic Effect","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"35. A Surface Integral Representation of the Tectonomagnetic Field Based on the Linear Piezomagnetic Effect","subitem_title_language":"en"}]},"item_type_id":"4","owner":"1","path":["4798","4800"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2008-05-30"},"publish_date":"2008-05-30","publish_status":"0","recid":"32934","relation_version_is_last":true,"title":["35. A Surface Integral Representation of the Tectonomagnetic Field Based on the Linear Piezomagnetic Effect"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2022-12-19T05:17:30.030891+00:00"}