{"created":"2021-03-01T06:51:04.402927+00:00","id":32405,"links":{},"metadata":{"_buckets":{"deposit":"0939f2da-1daf-4df0-9a2c-d03966191d82"},"_deposit":{"id":"32405","owner":"1","owners":[],"pid":{"revision_id":0,"type":"depid","value":"32405"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00032405","sets":["80:4535:4536:4537","9:504:4538:4539:4540"]},"author_link":["72453","72454","72455","72456","72457","72448","72449","72450","72451","72452"],"item_4_alternative_title_1":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"蔵王山，吾妻山の活動史と最近の噴火をもたらしたマグマ溜まり"}]},"item_4_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2016","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"3","bibliographicPageEnd":"39","bibliographicPageStart":"25","bibliographicVolumeNumber":"91","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_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"Since the 2011 Tohoku-Oki earthquake on March 11, 2011, several dormant volcanoes have shown signs of activity. In particular, many phenomena that are precursors to eruptions have been detected at Zao and Azuma volcanoes, which are located near the hypocenter of this earthquake. Eruption histories and current conditions of these volcanoes are reviewed, and the states of present sub-volcanic systems are considered on the basis of petrologic features of recent magmatic eruption products coupled with geophysical data. Both volcanoes have eruption histories of approximately 1 million years. At Zao, the first stage, ~1 Ma, is characterized by sub-aqueous eruptions of basaltic magma followed in stages by small to medium-sized andesitic stratovolcanoes building at ~0.5-0.04 Ma. The youngest stage, ~35 ka to the present, is characterized by explosive eruptions of basaltic andesite to andesitic magma. This stage is further divided into three phases: ~35 to 13 ka, ~9to 4 ka, and ~2 ka to the present. During the youngest phase, the Goshikidake cone-building phase, many historical eruptions were recorded; the youngest eruption from the present crater occurred in AD 1895. At Azuma, volcanic activity is divided into five stages: 1.2-0.8 Ma, 0.8-0.6 Ma, 0.6-0.4 Ma, 0.4-0.3 Ma, and less than 0.3 Ma. During each stage, small to medium-sized andesitic stratovolcanoes formed over the entire area of Azuma. The youngest activity began at about 7 ka in the eastern area. Five magmatic eruptions at ~6.7 ka, ~6.3 ka, ~5.9to 4.8 ka, ~4.3 ka, and ~AD 1331 and seven phreatic eruption episodes have been recognized by tephrostratigraphic studies. Many historical eruptions have also been recorded; the youngest eruption from the present crater occurred in AD 1977. Volcanic tremors were first detected at Zao in January 2013. Although such tremors were also recorded at Azuma, those with larger amplitudes have been detected since January 2010. The number of volcanic earthquakes increased beneath Zao in April 2015 and beneath Azuma in December 2014. At those times, volcanic tremors and deformation of the summit area were observed in both cases, which led to volcanic activity warnings. At both volcanoes, other precursory phenomena have been observed, including an increase in underground temperature revealed by total magnetic force surveys and an increase of geothermal activity. At Zao, the number of low-frequency earthquakes increased about one year before the first detection of volcanic tremors was reported. Magmatic eruptions of<~35 ka of Zao and<~7 ka of Azuma volcanoes produced basaltic andesites to andesites, which were formed by the mixing of mafic and felsic magmas. The felsic magmas are andesitic at Zao and dacitic at Azuma, containing about 60% and 65.5% SiO2, respectively. The temperature, pressure, and water content of these magmas are 955-970℃, 1.3-1.5 kb, and 1.7-1.8% H2O; and 880-890℃, 0.8-1.2 kb, and 2.75-3.25% H2O, respectively. The mafic magmas are basaltic in both cases, but that of Zao is slightly more differentiated than that of Azuma. In both cases, deeper mafic magmas infiltrated the shallower felsic magma chamber, which triggered the eruption. The felsic chamber locations, at ~6 km at Zao and ~4 km at Azuma, are deeper than the present shallow earthquakes. The shallow earthquakes are related to hydrothermal fluid released from shallow felsic chambers that have been reactivated. The deep earthquakes occurred in areas with a high P-wave to S-wave velocity ratio (Vp/Vs) at depths of about 20-37km below both volcanoes, where tomographic studies indicate melt. Therefore, the mafic magma probably originated from the melt.","subitem_description_type":"Abstract"}]},"item_4_full_name_3":{"attribute_name":"著者別名","attribute_value_mlt":[{"nameIdentifiers":[{"nameIdentifier":"72453","nameIdentifierScheme":"WEKO"}],"names":[{"name":"伴, 雅雄"}]},{"nameIdentifiers":[{"nameIdentifier":"72454","nameIdentifierScheme":"WEKO"}],"names":[{"name":"武部, 義宜"}]},{"nameIdentifiers":[{"nameIdentifier":"72455","nameIdentifierScheme":"WEKO"}],"names":[{"name":"足立, 辰也"}]},{"nameIdentifiers":[{"nameIdentifier":"72456","nameIdentifierScheme":"WEKO"}],"names":[{"name":"松井, るり子"}]},{"nameIdentifiers":[{"nameIdentifier":"72457","nameIdentifierScheme":"WEKO"}],"names":[{"name":"西, 勇樹"}]}]},"item_4_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.15083/0000032405","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_text_4":{"attribute_name":"著者所属","attribute_value_mlt":[{"subitem_text_value":"山形大学理学部地球環境学科"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Ban, Masao"}],"nameIdentifiers":[{"nameIdentifier":"72448","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Takebe, Yoshinori"}],"nameIdentifiers":[{"nameIdentifier":"72449","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Adachi, Tatsuya"}],"nameIdentifiers":[{"nameIdentifier":"72450","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Matsui, Ruriko"}],"nameIdentifiers":[{"nameIdentifier":"72451","nameIdentifierScheme":"WEKO"}]},{"creatorNames":[{"creatorName":"Nishi, Yuki"}],"nameIdentifiers":[{"nameIdentifier":"72452","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":"2017-06-12"}],"displaytype":"detail","filename":"IHO91301.pdf","filesize":[{"value":"8.7MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"IHO91301.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/32405/files/IHO91301.pdf"},"version_id":"e0ca9027-9cdc-4785-ab15-710b58947973"}]},"item_keyword":{"attribute_name":"キーワード","attribute_value_mlt":[{"subitem_subject":"Zao volcano","subitem_subject_scheme":"Other"},{"subitem_subject":"Azuma volcano","subitem_subject_scheme":"Other"},{"subitem_subject":"eruption history","subitem_subject_scheme":"Other"},{"subitem_subject":"2011 Tohoku-Oki earthquake","subitem_subject_scheme":"Other"},{"subitem_subject":"magma feeding system","subitem_subject_scheme":"Other"}]},"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":"Eruption Histories of Zao and Azuma Volcanoes and Their Magma Feeding Systems for Recent Activities","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Eruption Histories of Zao and Azuma Volcanoes and Their Magma Feeding Systems for Recent Activities","subitem_title_language":"en"}]},"item_type_id":"4","owner":"1","path":["4537","4540"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2017-04-26"},"publish_date":"2017-04-26","publish_status":"0","recid":"32405","relation_version_is_last":true,"title":["Eruption Histories of Zao and Azuma Volcanoes and Their Magma Feeding Systems for Recent Activities"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2022-12-19T05:16:25.800183+00:00"}