著者

田島 靖久 松尾 雄一 庄司 達弥 小林 哲夫

出版者

特定非営利活動法人 日本火山学会

雑誌

火山 (ISSN:04534360)

巻号頁・発行日

vol.59, no.2, pp.55-75, 2014-06-30 (Released:2017-03-20)

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The Kirishima volcanoes located in southern Kyushu are comprised of more than 20 volcanic edifices. The volcanoes occupy an elliptical area of approximately 330km2 with the WNW-ESE direction. Among the different types of volcanic edifices, the typical ones are compound maars and lava flows in Ebinokogen. We studied the volcanic history of Ebinokogen by geological examination of tephra layers and lava flows. After the Karakunidake-Kobayashi plinian eruption, seven tephra were formed in this area. We determined the ages of those tephra and two lava flows. The magmatic eruptions, produced Tamakino B tephra, occurred after Karakunidake-Kobayashi tephra eruption. The first activity in Ebinokogen from about 9.0 cal ka BP generated Fudoike lava flow, and Fudoike-Tamakino A tephra erupted from Fudoike crater. Karakunidake north-Ebino D tephra was generated from the northwest flank of Karakunidake at 4.3 cal ka BP, with debris avalanche and lahars. Phreatic Fudoike-Ebino C tephra erupted from the Fudoike crater at 1.6 cal ka BP. Ioyama-Ebino B tephra eruption started from around the 16th to 17th century with lava flow. Phreatic Ioyama east-Ebino A tephra erupted from Ioyama east crater in 1768 AD. The Ebinokogen area is one of the active regions of Kirishima volcanoes explicated by geophysical observations. Our results indicate cyclical tephra depositions mainly produced by small magmatic and strong phreatic eruptions in this area after the Karakunidake-Kobayashi pyroclastic eruption. Furthermore, the vent locations were found to migrate with each eruption.

著者

田島 靖久 宮地 直道 井上 公夫

出版者

日本第四紀学会

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.45, no.4, pp.287-301, 2006 (Released:2007-07-27)

参考文献数

31

被引用文献数

2 3

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日本最大の活火山である富士火山には, 山麓部に複数の扇状地が分布する. 本論では, 富士火山の西側に位置する上井出扇状地について, その形成過程を解明した. 上井出扇状地は堆積物の構成物質や地形より, その形成時期をYFM-K1~K3期の3時期に区分できる. このうち, YFM-K1期 (cal BC 3,400~2,100) は中期溶岩の噴出時期にあたり, cal BC 2,500頃には到達距離の長い岩樋火砕流が発生した. YFM-K2期 (cal BC 1,500~1,000) は, 比較的規模の大きな降下テフラや火砕流が噴出するとともに, 御殿場岩屑なだれと近接した時期に107m3オーダーの規模の大きな猪の窪ラハール-Aが発生した. YFM-K3期 (cal BC 800~AD 300) は, 湯船第2スコリア (Yu-2) をはじめとする山頂火口に由来する降下テフラの噴出時期に対応し, これらに伴うラハールが発生した.マグマ噴出率の変化と, cal BC 3,400以降の上井出扇状地における土砂堆積量の変化傾向は, おおむね一致していることが判明した. 上井出扇状地のYFM-K1期の場合, 大規模な降下テフラの発生が少なく, このため山体近傍に堆積する溶岩の供給量の変化は, 扇状地での堆積量の変化に大きく影響を与えていると考えられる. YFM-K2期については, 107m3オーダーのラハールが短時間に流出する現象が扇状地の形成に関与していた.

著者

田島 靖久 及川 純 小林 哲夫 安田 敦

出版者

特定非営利活動法人 日本火山学会

雑誌

火山 (ISSN:04534360)

巻号頁・発行日

vol.67, no.1, pp.45-68, 2022-03-31 (Released:2022-04-26)

参考文献数

105

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Shinmoedake is the compound volcano in Kirishima Volcano and the most active volcano in Japan, having recorded frequent magmatic eruptions during 1716-1717, 2011, and 2018. The three geological active periods of Shinmoedake in the last 8 ka were recorded by a geological survey (Tajima et al., 2013a). The geological eruptive time category of Shinmoedake is divided into long-term, middle-term, and short-term activities. Short-term activity is captured by monitoring and covers a period of several years or more. The magma eruption rates during middle-term activities were estimated to be several times higher than the long-term magma eruption rate. Moreover, the centers of magma eruptions within each middle-term period had stabilized in terms of location. Additionally, the magma eruption rates during each period of middle-term activity were not constant. Therefore, knowledge regarding the variation in the magma production of Shinmoedake during geologically short-term, middle-term, and long-term activities is required to understand its development and plumbing system. In this paper, we compile recent geological investigation results of Shinmoedake and propose a rational conceptual model of its current state supported by petrological and geophysical data. A well-known conceptual plumbing model of Kirishima Volcano was proposed by Kagiyama et al. (1997). The seismic attenuation spot (reservoir A) is located at a depth of 4-5 km below Karakunidake (Oikawa et al., 1994), and a wide P-wave velocity anomaly area (reservoir W) is situated at a depth of 10-15 km below Kirishima Volcano (Yamamoto and Ida, 1994). Recently, geophysical observations have indicated that magma was supplied from a depth of 8-10 km (reservoir B) to the western area of Shinmoedake during the 2011 magmatic eruption (Nakao et al., 2013). In addition, petrological analysis suggested two different sources of silicic magma from a level of reservoir A and mafic magma from a level of reservoir B (Suzuki et al., 2013a). Therefore, reservoir B might have been connected to reservoir A, where magma mixing occurred during the 2011 eruption. Furthermore, analysis of the deep low-frequency (DLF) earthquake of the 2011 eruption of Shinmoedake revealed that the DLF activities at a depth of 20-27 km (reservoir L1) in the eastern part of Kirishima Volcano were involved (Kurihara et al., 2019). Reservoirs L1 and B may also be connected. These results support the increasing activities of Kirishima Volcano revealed by the geological survey (Tajima et al., 2013a). It is concluded that the complex magma plumbing system of Shinmoedake may cause different magma eruption rates during periods of middle- and long-term activities.

著者

田島 靖久 林 信太郎 安田 敦 伊藤 英之

出版者

日本第四紀学会

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.52, no.4, pp.151-171, 2013-08-01 (Released:2013-09-28)

参考文献数

48

被引用文献数

7

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霧島火山の新燃岳では2011年に軽石を伴う噴火を起こした.新燃岳は,最近1万年間内に3回の軽石噴火をしているが,2011年噴火はこれらより短い間隔をもって噴火した.また,新燃岳の火口壁には複数の溶岩の露出が知られていたが,その噴出年代は解明されていない.そこで,新燃岳の長期的活動史を理解するために野外調査・年代測定・全岩化学分析を行い,テフラと溶岩の関係を考察した.その結果,既知のテフラ以外に4.5,2.7,2.3 cal ka BPにテフラ噴出があったことが新たに判明した.また,溶岩はテフラとの関係より牛のすね火山灰以前,新燃岳-新湯テフラ以前,新燃岳-享保テフラ以前,およびそれ以降に分けられる.新燃岳は,少なくとも 5.6~4.5 ka, 2.7~2.3 ka, 18世紀以降の3回の活発にマグマを噴出する活動的な期間と静穏な期間を繰り返しており,現在は活動的な期間に位置づけられる.

著者

中野 俊 高田 亮 石塚 吉浩 鈴木 雄介 千葉 達朗 荒井 健一 小林 淳 田島 靖久

出版者

国立研究開発法人 産業技術総合研究所 地質調査総合センター

雑誌

地質調査研究報告 (ISSN:13464272)

巻号頁・発行日

vol.57, no.11-12, pp.387-407, 2007-03-31 (Released:2014-06-11)

参考文献数

23

被引用文献数

1 4

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富士火山噴出物の噴火年代決定を目的として産総研が実施したトレンチ調査のうち,北東山麓で行ったトレンチ調査結果及びそれに関連した露頭観察の結果をまとめ,そこから得られた放射性炭素年代測定値を合わせて報告する.トレンチ調査の対象は,新富士旧期の大臼,小臼などの火砕丘群及び新富士新期の檜丸尾,鷹丸尾,中ノ茶屋,雁ノ穴丸尾,土丸尾などの溶岩流群である.

著者

及川 純 田島 靖久

出版者

特定非営利活動法人 日本火山学会

雑誌

日本火山学会講演予稿集 2020 (ISSN:24335320)

巻号頁・発行日

pp.8, 2020 (Released:2021-02-01)

著者

田島 靖久 松尾 雄一 庄司 達弥 小林 哲夫

出版者

特定非営利活動法人日本火山学会

雑誌

火山 (ISSN:04534360)

巻号頁・発行日

vol.59, no.2, pp.55-75, 2014

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The Kirishima volcanoes located in southern Kyushu are comprised of more than 20 volcanic edifices. The volcanoes occupy an elliptical area of approximately 330km^2 with the WNW-ESE direction. Among the different types of volcanic edifices, the typical ones are compound maars and lava flows in Ebinokogen. We studied the volcanic history of Ebinokogen by geological examination of tephra layers and lava flows. After the Karakunidake-Kobayashi plinian eruption, seven tephra were formed in this area. We determined the ages of those tephra and two lava flows. The magmatic eruptions, produced Tamakino B tephra, occurred after Karakunidake-Kobayashi tephra eruption. The first activity in Ebinokogen from about 9.0 cal ka BP generated Fudoike lava flow, and Fudoike-Tamakino A tephra erupted from Fudoike crater. Karakunidake north-Ebino D tephra was generated from the northwest flank of Karakunidake at 4.3 cal ka BP, with debris avalanche and lahars. Phreatic Fudoike-Ebino C tephra erupted from the Fudoike crater at 1.6 cal ka BP. Ioyama-Ebino B tephra eruption started from around the 16^<th> to 17^<th> century with lava flow. Phreatic Ioyama east-Ebino A tephra erupted from Ioyama east crater in 1768 AD. The Ebinokogen area is one of the active regions of Kirishima volcanoes explicated by geophysical observations. Our results indicate cyclical tephra depositions mainly produced by small magmatic and strong phreatic eruptions in this area after the Karakunidake-Kobayashi pyroclastic eruption. Furthermore, the vent locations were found to migrate with each eruption.