著者

中村 保夫 他KAIKO計画・LEG III乗船科学者一同

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.29, no.4, pp.305-306, 1984

著者

田中 康裕 古田 美佐夫 中礼 正明

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:24330590)

巻号頁・発行日

vol.21, no.3, pp.185-197, 1976-12-15 (Released:2018-01-15)

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The authors carried out temperature measurement of the ground surface at the Nakadake Crater of Asosan, used an infrared radiation thermometer, and compared the twice observation results at the calm period and the eruption time of the volcano. High temperature zones in the crater bottom and the crater wall were situated at the north half part of the Nakadake Crater, and anomalous high temperature zones at the eruption time extended about ten times as large as that of the calm period. Furthermore, these anomalous high temperature values at the eruption time were 10℃ to 15℃ higher than that of the calm period. These suggest that some thermally anomalous areas in the crater may change their thermal characteristics before or at the future eruptions. The thermal infrared surveys are very useful to volcano observation for the monitoring of some potentially hazardous crater, and these surveys can be done with safety and quickness.

著者

竹内 晋吾

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 2017 (ISSN:24335320)

巻号頁・発行日

pp.219, 2017 (Released:2018-02-01)

著者

荒井 健一 小山 真人

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 1996.2 (ISSN:24335320)

巻号頁・発行日

pp.25, 1996-11-05 (Released:2017-02-10)

著者

宝田 晋治 星住 英夫

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 2016 (ISSN:24335320)

巻号頁・発行日

pp.26, 2016 (Released:2017-02-07)

著者

風間 卓仁

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.64, no.3, pp.189-212, 2019-09-30 (Released:2019-10-15)

参考文献数

107

著者

和田 恵治 佐野 恭平

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.60, no.2, pp.151-158, 2015-06-30 (Released:2017-03-20)

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The Shirataki obsidian-rhyolite field (Shirataki Geopark, Hokkaido) contains many outcrops of densely compact obsidian layers of excellent quality. The Shirataki obsidian lavas (SiO2=76.7-77.4 wt.%) were erupted at ca. 2.2 Ma and formed a monogenetic volcano comprising 10 obsidian-rhyolite lava units. The thickness of the units ranges from 50 to > 150m, and each unit comprises a surface clastic zone, an upper dense obsidian zone, an upper banded obsidian zone, a central thick rhyolite zone, a lower banded obsidian zone, a lower dense obsidian zone, and a lower clastic zone. The dense obsidian is > 98% glass with microlites of mainly magnetite and plagioclase, and rare plagioclase phenocrysts. Obsidian and rhyolite within single lava flows have similar bulk-rock compositions and number density of microlites, although the rhyolite contains glass with perlitic cracks and a large amount of crystalline material (spherulites and lithophysae), while the dense obsidian contains 0.4-0.8 wt.% H2O. These geological and petrological features indicate that the formation of obsidian and rhyolite layers in the lava units was controlled mainly by the timing of the vesiculation and degassing of magmas, in addition to the cooling effect.

著者

早川 由紀夫 中島 秀子

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.43, no.4, pp.213-221, 1998-08-31 (Released:2017-03-20)

参考文献数

33

被引用文献数

2

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The 1108 eruption of Asama is the largest among numerous eruptions of the volcano during the Holocene. The magnitude is twice as large as that of the notorious 1783 eruption, which killed about 1,400 people. It is also the oldest written eruption of Asama. Chuyuki, which was written in Kyoto, 300 km SW of Asama, describes that the eruption started on September 29, 1108, by the Julian calendar, and that fields of rice and other crops were severely damaged. Many fatalities are strongly suspected by the distribution of the Oiwake ignimbrite, but no description is given for human loss in Chuyuki. A thin pumice layer intercalated between the 1108 scoria and the 1783 pumice can be correlated to a record of Pele’s hair-fall in Kyoto in 1596. As many as 800 fatalities at the summit in 1598 described in Todaiki cannot be true. Tenmei Shinjo Hen’iki, which describes that a number of villages along the Jabori River were swept away by hot lahars in 1532, is not a contemporary document. It was written in the late 18th century. Fifteen fatalities at the summit in 1721 can be true. After the 1783 eruption, Asama had been relatively quiet for 100 years. During the early and middle 20th century, Asama had been very active with a peak of 398 times vulcanian explosions in 1941. About 30 Iives were lost at the summit, in the 20th century, by 12 explosions among the total about 3,000 explosions.

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

日本火山学会講演予稿集 2015 (ISSN:24335320)

巻号頁・発行日

pp.15, 2015-09-28 (Released:2017-02-10)

著者

安部 祐希

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.64, no.2, pp.139-145, 2019-06-30 (Released:2019-07-06)

参考文献数

32

著者

川本 竜彦

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:24330590)

巻号頁・発行日

vol.35, no.1, pp.41-56, 1990-04-14 (Released:2018-01-15)

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The Kannabe monogenetic volcano group is situated in the back-arc region of southwest Japan and is composed of six scoria cones (Nishiki, Yamanomiya, Buri, Otsukue, Kiyotaki and Kannabe) and one scoria bed (Nishibashi-kita). Stratigraphic relationships between various groups of ejecta are inferred from the tephrochronology of fall scoriae and widespread tephra. With the exception of Yamanomiya and Kiyotaki, the volcanic activity began with the formation of scoriae and ended with a phase of lava flow extrusion. No such lava flows are developed in either Yamanomiya or Kiyotaki. The volcanic activity of the Kannabe volcano group mainly took place prior to 21,000-22,000 y. B. P. with the exception of the Kannabe scoria cone itself, which was active before 6,000-6,500 y. B. P. In the vicinity of the Yamanomiya scoria cone, a new debris avalanche deposit has been discovered. This consists mainly of blocks of the Yamanomiya scoria cone, which preserve their original stratification defined by preferential alignment of scoriae and spatters.

著者

安田 敦 馬場 章 藤井 敏嗣 外西 奈津美

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.64, no.2, pp.83-101, 2019-06-30 (Released:2019-07-06)

参考文献数

52

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Gabbroic inclusions newly found in the Yakeno lava flow, erupted about 1300 years ago on the northwestern flank of Fuji volcano, are divided into two groups; one consists of troctolite and the other consists of olivine gabbronorite and gabbronorite. Troctolite fragments are considered to originate from shallow dykes because of their mineral composition and high porosity. On the other hand, estimated equilibrium conditions of gabbronorite and olivine gabbronorite are 1020-1050°C and 250-380MPa, showing their deep origin; probably they had been caught in the Yakeno magma (i.e. the magma erupted as the Yakeno lava flow) at differentiated small magma bodies just above a substantial basaltic magma chamber of Fuji volcano. Pre-eruptive temperature and water content of the Yakeno magma are evaluated by olivine-liquid thermometer and plagioclase-liquid hygrometer to be 1090°C and 2.8wt%, respectively. So the viscosity of the Yakeno magma is calculated to be several tens Pascal second. Therefore the minimum ascent velocity required to lift the gabbroic fragments is ca.10m/h, implying that the Yakeno lava flow had ascent without significant pause en route to the surface.

著者

伴 雅雄 及川 輝樹 山崎 誠子 後藤 章夫 山本 希 三浦 哲

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.64, no.2, pp.131-138, 2019-06-30 (Released:2019-07-06)

参考文献数

27

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Based on the history of volcanic activity of Zao stage VI, we examined possible courses of future activity of Zao volcano. All activities will start with precursory phenomena. Next, phreatic eruptions from Okama crater or other place inner part of Umanose caldera will occur, and may cause ballistic materials release, ash fall, pyroclastic surge, and lahar. The possibility of small scales edifice collapse and lava flow swelled out is very low but should be included. When the activity progresses, magmatic eruptions will be taken place from Goshikidake, and cause same phenomena as in the phreatic eruptions but larger in scale. The possibility magmatic eruption takes place without preceding phreatic eruption can not be excluded. Rarely, the activity will go up further and resulted in sub-Plinian eruption. Aside from the above sequence, larger scale phreatic eruption from Goshikidake area should be listed, although the possibility of this is very low.

著者

金崎 裕之 伊豆 智幸 森山 裕二 島田 徹 手束 宗弘 永田 直己 皆川 淳 金井 啓通 永谷 圭司 谷島 諒丞

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.2017, pp.195, 2017

著者

横山 泉

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.34, no.2, pp.125-126, 1989

著者

木下 茜 寅丸 敦志

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 2016 (ISSN:24335320)

巻号頁・発行日

pp.15, 2016 (Released:2017-02-07)

著者

藤井 敏嗣

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.48, no.1, pp.157-159, 2003

参考文献数

5

著者

岩森 光

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.1-22, 2016-03-31 (Released:2017-03-20)

被引用文献数

1

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Earth’s mantle constitutes the largest sub-system of the whole Earth system, involving 70% of the total mass, ~80% of the heat capacity, and more than 50% of the internal heat generation by radioactive decay. Therefore, the mantle and the inherited dynamics may control the whole system to a great extent, e.g., in terms of convective motion (including plate motion as its surface expression) and heat transport from the core to the surface, regulating the core cooling and dynamo that eventually affects the surface environment and life. First the basic structures and dynamics of the mantle convection are described, which demonstrate that the surface cooling dominantly drives the convection, creating buoyancy of several to 10 times greater than that generated near the core-mantle boundary. This estimate for the much larger role of near-surface cooling is consistent with the seismic tomography. Then various types of observations on the structures and dynamics of mantle, particularly three boundary layers (i.e., the near-surface, mid-mantle around 660km discontinuity, and core-mantle boundary) have been reviewed and are compared with the simple estimation. Of these, the ’geochemical probe’ approach, which utilizes composition (in particular the isotopic composition) of young basalts that fingerprint geochemical nature of the mantle materials, has been reviewed in conjunction with convective regimes. The latest result of high spatial resolution has revealed that the mantle can be divided into the eastern and western hemispheres, in terms of an anciently (several hundred million years ago) subducted fluid-component. The spatial pattern is strikingly similar to the hemispherical seismic structure of the inner core. Based on these observations, a model for ‘top-down hemispherical dynamics’ is introduced, as a result of focused subduction towards the supercontinents that existed mostly in the eastern hemisphere from ~900 to 250 million years ago (i.e., Rodinia, Gondwana and Pangea). The cooled domain of mantle may absorb heat from the eastern hemisphere of the core, resulting in faster growth and velocity of the eastern half of the inner core. Such ‘top-down’ dynamics is consistent with the various types observations and arguments (made in the first half of this paper) on mantle convection.

著者

西村 太志 内田 東

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.50, no.5, pp.387-391, 2005

参考文献数

11

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We analyze five explosion earthquakes observed at Asama volcano in 2004. The main phase consisting of Rayleigh wave is well explained by a vertical downward single force with peak amplitude of 10¹⁰-10¹¹ N and pulse width of 5-6s. These source parameters are in the range expected from a scaling relation presented by Nishimura and Hamaguchi (1993), which suggests that the 2004 explosions of Asama volcano are typical Vulcanian eruptions. The internal pressure built up beneath the crater is estimated to be 0.2-1.5MPa, which tends to become large after the formation of lava dome in the crater.

著者

佐藤 彰 永尾 隆志 堀川 義之 堀江 智敬

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.2008, 2008