{"created":"2021-03-01T06:52:40.675193+00:00","id":33848,"links":{},"metadata":{"_buckets":{"deposit":"7ff69d5b-f73a-4a32-9c34-9a1f4485f1a5"},"_deposit":{"id":"33848","owner":"1","owners":[],"pid":{"revision_id":0,"type":"depid","value":"33848"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00033848","sets":["80:4535:4997:5001","9:504:4538:4999:5002"]},"author_link":["132068","132067"],"item_4_alternative_title_1":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"28.北海道,駒ケ岳火山の軽石流堆積物"}]},"item_4_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"1960-07-10","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"3","bibliographicPageEnd":"466","bibliographicPageStart":"451","bibliographicVolumeNumber":"38","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":"Pumice-flows discharged from Komagatake Volcano, on June 17, 1929, descended from the lower, and perhaps slowly rising outer part of a vertically rising column of ash-laden cloud, during the paroxysmal phase of the eruption. The outer part of an ash column became denser than the surrounding atmosphere, and pumice-laden dense cloud discharged laterally. Crystals and coarse pumice-blocks were concentrated in the lower layers of descending dense cloud, and crystal-rich pumice-flow deposits were deposited on the mountain-slope of the volcano. Similar pumice-flows were discharged by former eruptions, and their deposits are quite similar to those of the 1929 eruption.|北海道南端の渡島半島東部に位置する駒ケ岳火山は,活火山として知られ,古くから烈しい噴火を繰返えしてきた.寛永17年(1640年),安政3年(1856年),昭和4年(1929年)の噴火は特に烈しかつた.昭和4年の噴火の際には,軽石流の噴出が起つた.噴火は6月17日午前0時30分頃より始まり,午前10時頃に烈しい爆発が起つた.噴煙は空中高く噴き上げられ,軽石や火山礫火山灰が間断なく拠出された.正午を少しすぎた頃,最初の軽石流が噴出した.噴煙はますます烈しさを増し,その高さは午後2時頃には13,200mと測定された.午後2時より3時にかけて,軽石流はあいついで噴出し,北西,南西,南東斜面を流下した.その後も軽石流の噴出は続き,午後10時頃最後の軽石流が南西斜面に流下した.噴火は午後11時30分頃まで続き,そのご衰えて,18日午前1時30分には降灰もおさまつた.軽石流は,北,西,東方の山腹斜面上に拡がり,その面積は27～30km2におよんだ.堆積物の厚さを平均5mと仮定すれば,総体積は約0.15km3とたる.筆者はこの軽石流堆積物の試料を数ケ所から採集して機械分析を行つた.その結果は一般の軽石流堆積物と共通の特徴を示した.すなわち,分級が相当悪く,粗粒部および細粒部に長く尾を引き,主モードの位置はφスケールでO～1の間に常に現れ,粗粒部に副モードを持ち,採集地点の相違にかかわらず共通の粒度分布を示し,中位粒径の値はほとんど変化がない,等の特徴を示した.駒ケ岳火山の軽石流堆積物の粒度組成の特徴として特に注目すべき点は,結晶粒の集中が著しいことである.すなわち,軽石塊では,斑晶が45%に対してガラス質が55%を占めているが,軽石流堆積物では,軽石塊および石質破片を除くと,結晶粒がガラス破片よりもかなり多くの比率を占めている.ヒストグラムで見られるような中核部の顕署な主モードがこれを表わしている.結晶粒の集中は堆積物の下部において著しく,これに対し,堆物の上部および末端部では粗粒の軽石塊の集中が認められる.軽石流堆積物のこのような特徴は,軽石流の噴出の機構を示唆するもののように考えられる.すなわち,垂直に上昇する噴火雲の中の比較的ゆるやかに上昇する外側部で,比重の大きな結晶粒と粗粒の軽石塊とが分級されて集中し,その部分が周囲の大気よりも比重が大きくなつて,側方に流下して軽石流を生じたと解釈することも可能であろう.いつたん軽石流の流下が始まれば,その流下雲の中で更に結晶粒の分級が続き,堆積物の下部に集中すると考えられる.さらに粗粒の軽石流は堆積物の上部および末端に集中する.細粒のガラス破片は上層にまい上り,粗粒な堆積物の前面にそつて堆積して,細粒のガラス質の軽石流堆積物となる.駒ケ岳火山では,古くから火山砕屑流を繰返して噴出した.筆者はこれらの火砕流の堆積物から4個の試料を採集して,機械分析を行つた.その結果は昭和4年の軽石流堆積物と全く同一であつた.駒ケ岳火山では,同じような噴火が古くから繰返えして行われたものと見られる.駒ケ岳火山は,かつて烈しい爆発により,その頂部が破壊され,泥流が発生して南方および東方山麓に流下し,特徴的な流れ山地形を作つた.この泥流堆積物から俵の資料を採集して機械分析を行つた.泥流堆積物では,分級が一層悪く,粒度分布の形は不安定で,中位粒径の値も大きく変化する,等の特徴が認められた.","subitem_description_type":"Abstract"}]},"item_4_full_name_3":{"attribute_name":"著者別名","attribute_value_mlt":[{"nameIdentifiers":[{"nameIdentifier":"132068","nameIdentifierScheme":"WEKO"}],"names":[{"name":"村井, 勇"}]}]},"item_4_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.15083/0000033848","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":"Murai, Isamu"}],"nameIdentifiers":[{"nameIdentifier":"132067","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":"2017-06-27"}],"displaytype":"detail","filename":"ji0383007.pdf","filesize":[{"value":"1.6 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"ji0383007.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/33848/files/ji0383007.pdf"},"version_id":"b451a74a-7e13-48ed-b091-51efb76f072d"}]},"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":"28. Pumice-flow Deposits of Komagatake Volcano, Southern Hokkaido","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"28. Pumice-flow Deposits of Komagatake Volcano, Southern Hokkaido","subitem_title_language":"en"}]},"item_type_id":"4","owner":"1","path":["5001","5002"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2008-05-30"},"publish_date":"2008-05-30","publish_status":"0","recid":"33848","relation_version_is_last":true,"title":["28. Pumice-flow Deposits of Komagatake Volcano, Southern Hokkaido"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2022-12-19T04:09:09.020809+00:00"}