著者

小坂 丈予 野上 健治 吉田 稔

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 (ISSN:24335320)

巻号頁・発行日

vol.1994, 1994

著者

横尾 亮彦 石井 杏佳

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.66, no.3, pp.229-240, 2021

著者

石峯 康浩

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.61, no.1, pp.183-198, 2016-03-31 (Released:2017-03-20)

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This paper presents some basic concepts on possible cooperative framework for contributing to disaster mitigation during volcanic eruptions with the intention of enhancing discussion among members of the Volcanological Society of Japan. At first, this paper describes some examples of problems that have been argued during recent volcanic eruptions because of improper risk communication of volcanologists, and then, outlines the present state of a coordination system for effective disaster assistance by multiple stakeholders with a focus on recent efforts in public health and medical communities. Preliminary ideas on “Expert Assistance Team during Volcanic Crises” are also presented for further discussions.

著者

吉村 俊平

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.66, no.4, pp.375-384, 2021-12-31 (Released:2022-02-22)

参考文献数

24

著者

松本 亜希子 中川 光弘 小林 卓也 石塚 吉浩

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.66, no.4, pp.255-279, 2021-12-31 (Released:2022-02-22)

参考文献数

37

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The Tokachidake volcano group, central Hokkaido, is one of the most active volcanoes in Japan; three magmatic eruptions occurred from the crater area on the northwestern flank of Tokachidake in the 20th century. The Sandan-yama, Kamihorokamettokuyama, and Sampōzan edifices are on the southern flank of the volcano, and the first two bound the west-facing Nukkakushi crater. Although fumarolic activity and hydrothermal alteration are ongoing at Nukkakushi crater, its eruptive history remains unknown. Therefore, we performed a geological investigation of the Nukkakushi crater area. Based on topographical features, we inferred the following eruptive history. Sampōzan and Kamihorokamettokuyama formed during ca. 70-60 ka, after which the northern flank of Sampōzan collapsed and a new edifice (Nukkakushi volcano) was built within the collapse scarp. Finally, the collapse of the western flank of Nukkakushi formed Nukkakushi crater—perhaps during the Holocene, according to previous work. We identified eight Holocene eruptive products generated from the Nukkakushi crater area, the most recent of which was generated from a crater on the western flank of Sandan-yama sometime since the early 18th century. We also recognized three debris avalanche/landslide deposits that were generated within the last 750 years. Comparing the eruptive products of the northwestern crater area of Tokachidake with those of the Nukkakushi crater area revealed that magmatic eruptions from the two craters alternated until 1.8 ka. Their distinct magmatic compositions suggest the simultaneous existence of two isolated magma systems beneath Tokachidake and Nukkakushi, at least until that time. Since 1.8 ka, magmatic eruptions at the northwestern crater area of Tokachidake and phreatic eruptions at the Nukkakushi crater area have occurred in parallel. Moreover, around Nukkakushi crater, small-scale collapses/landslides have occurred. Previous studies recognized hydrothermal changes at Nukkakushi crater area, originating from the northwestern crater area of Tokachidake around the last two magmatic eruptions; it is therefore presumed that the Nukkakushi crater area was hydrothermally altered, even during periods of little eruptive activity. Such continuous and pervasive hydrothermal alteration explains the frequent collapses of edifices. The parallel yet contrasting eruptive activities in these adjacent areas are important for forecasting future eruptive activities and mitigating volcanic hazards.

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

宝田 晋治

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 2019 (ISSN:24335320)

巻号頁・発行日

pp.46, 2019 (Released:2020-04-13)

著者

水上 武

出版者

特定非営利活動法人 日本火山学会

雑誌

火山.第2集

巻号頁・発行日

vol.13, no.1, 1968

著者

藤原 善明 飯島 聖 坂井 孝行 加藤 幸司 中村 政道 内藤 宏人 山里 平 中禮 正明 平松 秀行 上田 義浩

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 (ISSN:24335320)

巻号頁・発行日

vol.2004, 2004

著者

ラカンナ ジョルジオ 市原 美恵 岩國 真紀子 武屋 実 井口 正人 リペペ マウリチオ

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 (ISSN:24335320)

巻号頁・発行日

vol.2012, 2012

著者

中田 節也

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.60, no.2, pp.143-150, 2015-06-30 (Released:2017-03-20)

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Statistical treatment of volcanic eruptions clearly shows the regularity of power law between the frequencies and the scales not only in the global scale but also in regional and individual volcano scales. However, ancient smaller eruption events tend to be not recorded, compared with recent data. In the log frequency-VEI plot, incompletely normalized frequency which ignores the time-dependent nature of the database, provides a gentler regression line than when the data time-dependence is considered; that is, the former reflects low numbers of small eruptions insufficiently recorded. The slopes of the regression lines are similar, irrespective of area scales. This regularity may help our understanding about the potential of future large eruptions in not only individual volcanoes but also caldera regions. Volcanic activity in Japan has been quiet recently; no VEI 4 eruptions occurred after the early 20th Century, and no VEI 5 eruptions did since the middle 18th Century. Considering the regularity of volcanic eruptions in the arc scale, it is likely that Japan will experience these large eruptions near future.

著者

田中 実 浜田 信生

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 1991.2 (ISSN:24335320)

巻号頁・発行日

pp.159, 1991-10-14 (Released:2017-02-10)

著者

石塚 治

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.61, no.1, pp.91-100, 2016-03-31 (Released:2017-03-20)

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How subduction begins and its consequences for global tectonics remain one of the essential outstanding problems of plate tectonics. Two different endmember mechanisms for subduction initiation have been hypothesized: spontaneous, and induced (or forced). Numerical models suggest that subduction initiation is induced by externally forced compression along a preexisting discontinuity in an oceanic plate such as a fracture zone or transform faults. However, it has been pointed out that spontaneous subduction must have occurred at some points in Earth's history to initiate plate tectonics, and recent numerical models demonstrated that lateral thermal/compositional buoyancy contrast along plate discontinuity or within lithosphere can cause spontaneous subduction initiation. Recent geological and geophysical surveys in the Izu-Bonin-Mariana fore-arc have revealed igneous processes in the initial stages of subduction. The oldest magmatism after subduction initiation generated MORB-like fore-arc basalts, which was associated with seafloor spreading caused by onset of sinking of slab into mantle. Then boninitic magmatism followed by tholeiitic to calc-alkaline arc lavas collectively makes up the extrusive sequence of the fore-arc crust. This magmatic evolution from initial basaltic magmatism to establishment of normal arc magmatism took several million years. Fore-arc stratigraphy observed in the Izu-Bonin-Mariana arc shares some of the key geologic and petrologic characteristics with many supra-subduction zone ophiolite, which implies that fore-arc crustal section produced in the initial stage of oceanic island arc formation could correspond to in-situ section of supra-subduction zone ophiolite prior to obduction. Recent ocean drilling projects targeting initial stage of the Izu-Bonin-Mariana arc inception revealed that subduction initiation to form the Izu-Bonin-Mariana arc took place spontaneously. The drilling results also revealed that the whole arc was established on the ocean crust produced associated with subduction initiation.

著者

林 信太郎

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 (ISSN:24335320)

巻号頁・発行日

vol.2003, 2003

著者

津久井 雅志

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.56, no.2-3, pp.89-94, 2011-06-30 (Released:2017-03-20)

参考文献数

9

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Old historical documents on 1779 AD An’ei eruption of Sakurajima, southwest Japan were collected from distal places as well as those from neighboring area of the volcano. These records revealed that the ash-fall front traveled to the northeast at about 50-100km/h, reached as far as Tohoku district 1200km from Sakurajima, and covered area of ca. 2.33×105km2. Investigation of old documents helped to improve understanding of behavior of the volcano and environmental effects at the time of infrequent and great eruption. The wide distribution of ash-fall in 1779 Sakurajima eruption suggests that there is a high potential that ash discharged by future eruption of Sakurajima may cover down through the mainland of Japan. We should keep in mind both physical and economical effects of ash-fall in assessing the activity and making the scenario of an eruption.

著者

久野 久

出版者

特定非営利活動法人 日本火山学会

雑誌

火山.第2集

巻号頁・発行日

vol.12, no.2, 1967

著者

久野 久

出版者

特定非営利活動法人 日本火山学会

雑誌

火山.第2集

巻号頁・発行日

vol.8, no.1, 1963

著者

一色 直記

出版者

特定非営利活動法人 日本火山学会

雑誌

火山.第2集 (ISSN:04534360)

巻号頁・発行日

vol.17, no.2, pp.99, 1972

著者

久野 久

出版者

特定非営利活動法人 日本火山学会

雑誌

火山.第2集

巻号頁・発行日

vol.5, no.1, pp.61-62, 1960

著者

久野 久

出版者

特定非営利活動法人 日本火山学会

雑誌

火山.第2集

巻号頁・発行日

vol.1, no.1, 1957