著者

佐藤 博明 原 郁男

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

巻号頁・発行日

vol.1990, no.2, 1990-11-06

著者

及川 輝樹 八木原 寛 高 美喜男 平野 舟一郎 中野 俊 中尾 茂 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.58, no.4, pp.563-567, 2013-12-27 (Released:2017-03-20)

著者

三浦 大助 荒井 健一 土志田 潔 落合 達也 田中 倫久 飯田 高弘

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

巻号頁・発行日

vol.2008, 2008-10-10

著者

黒墨 秀行 土井 宣夫

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

巻号頁・発行日

vol.1994, no.2, 1994-10-20

著者

小林 淳 萬年 一剛 奥野 充 中村 俊夫 高田 亮

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

巻号頁・発行日

vol.2004, 2004-10-19

著者

平田 由紀子

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

巻号頁・発行日

vol.1990, no.1, 1990-04-05

著者

西村 裕一 荒牧 重雄

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.44, no.1, pp.51-53, 1999-03-05

参考文献数

6

被引用文献数

1

著者

西 潔 石原 和弘

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.5, pp.407-413, 2003-11-06

参考文献数

11

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A new scheme for hypocenter calculation is proposed for volcanic regions. The scheme finds the global minimum of the travel time residual, and the resulting solution is more stable than that from the conventional Geiger's method, especially when the number of observations is small or the station distribution is unsuited. In the first step (Step 1) of this scheme, the target area js parameterized by the node. The node distance depends on the heterogeneity of the velocity structure; usually about 0.3-1 km is sufficient. Travel times between nodes and stations are stored. In the first half of the second step (Step 2A), a node is sought that minimizes the sum of squares of the travel time residuals for the event. By changing the depth of this node, a set of initial hypocenter candidates is generated. In the following step (Step 2B), with these candidates for the initial hypocenter, precise locations of the event are obtained by nonlinear calculations using the simplex method. The hypocenter with minimum travel time residual is then selected as the most probable hypocenter. For the travel time calculation, the 3-D robust seismic ray tracer known as Fermat (Nishi, 2001) is used. If the velocity structure and the locations of the observation stations do not change, the results of Step 1 are effective for all events. Consequently, repetitions of only Step 2A and 2B are sufficient for every event. Successful outcomes of calculation using synthetic and actual data are obtained with practicable CPU times.

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.

著者

山田 浩之 佐藤 元宣 小笠原 永久 吉本 充宏

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

巻号頁・発行日

vol.2015, 2015-09-28

著者

山県 耕太郎 町田 洋 新井 房夫

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

巻号頁・発行日

vol.1986, 1986

著者

勝井 義雄

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.12, no.3, 1967-12-01

著者

勝井 義雄

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.1, 1972-06-01

著者

宮地 直道

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.29, no.1, pp.17-30, 1984-04-01

被引用文献数

3

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"Fuji 1707 Tephra" was thrown out from the three craters on the upper southeast flank of Fuji Volcano on December 16 to 31, 1707 (TSUYA, 1955). It is composed of scoria beds named Ho-II to -IV and lowest two pumice beds named Ho-I. Ho-I and -II are probably originated from the second and the third craters and Ho-III and -IV are from the first crater on the basis of distribution of ejecta and characteristics in apparent densities. Ho-I_a, the lower Ho-I, is studied with respect to its mode of eruption, transportation and sedimentation. This bed is composed of white to pale brownish pumice, and is readily recognizable in the field and traceable over 130 km eastward from the source. Ho-I_a is the Plinian pumice-fall deposit and its volume is calculated to be 0.067 km^3 by the method of "Cross section area" (SUZUKI et al., 1973). The axis of maximum pumice diameters (MP), maximum lithic fragment diameters (ML) and median diameters of grains (Md) run along the southern margin of the distribution area. The same feature is recognized in the apparent density distribution for pumice fragments. More than 130 km eastward from the source, such an asymmetric distribution for MP is preserved. These facts suggest that the eruption column of Ho-I_a was affected by the strong westerlies in the upper atmosphere and the local SW winds in the lower one. The present meteorological data support this interpretation. Consequently, it is concluded that the irregular distribution of this Plinian tephra was originated by the differences in wind direction and velocity due to the altitude.

著者

鎌田 清吉

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.18, no.2, 1973-08-01

著者

中村 眞人

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

巻号頁・発行日

vol.2002, 2002

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.61, no.1, pp.211-223, 2016

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The main stream of the researches for prediction of volcanic eruption in Japan has been promoted through the national program which was established in 1974. The research has been advanced based on the development of basic volcanology and on the accumulation of practical knowledge obtained through the occasional volcanic eruptions. As it was shown in the review of the recent volcanic eruptions in Japan and the measures taken to mitigate the disasters caused by these eruptions, the prediction of volcanic eruptions in Japan is, however, on the stage of empirical pattern recognition. It is still far away from prediction based on the models of the underlying dynamics of volcano. Even in such situation, public society asks when and where eruption will occur, and how long the eruption will continue. It is difficult to answer these questions; however it is necessary to provide useful information based on the monitoring of eruption and the application of the available knowledge for the mitigation of volcanic disaster. In this context, several issues which might be concerned in the research of prediction of volcanic eruption and in developing the measures to mitigate volcanic disasters are described.

著者

津久井 雅志 荒牧 重雄

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.35, no.2, pp.231-248, 1990-07-02

被引用文献数

5

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22,000 years ago, about 100 km^3 of magma erupted from the northrn end of Kagoshima Bay, southern Kyushu. The eruption produced 5 units of pyroclastic deposits; (1) 98 km^3 of airfall pumice (Osumi pumicde fall, OS), (2) 13 km^3 of oxidized, fine-grained Tsumaya pyroclastic flow (TSU), (3) Kamewarizaka breccia (KM) of the new vent-opening and enlargement stage, (4) 250 km^3 of Ito pyroclastic flow (ITO) at the climactic stage, (5) >50 km^3 of co-ignimbrite ash fall (AT ash). Phenocryst mineral assemblage throughout the whole sequence is ubiquitously plag+qtz+opx(Mg#45-60) +mt+il. One exceptional sample (ITO 11c) carries Fe-rich oliv (Fo 26-28) and cpx beside other phases. Fifty-five new XRF analyses of 10 major and 15 trace elements show that the majority of the erupted magma consisted of a remarkably homogeneous, high-silica rhyolite with SiO_2 74-76.5%(H_2O free and 100% normalized). The maximum fluctuation found both in major and trace elements is ±40%. These variations can be explained by the crystal-liquid separation near the roof of the magma reservoir. Mt-il temperatures and opx-mt-qtz pressures show narrow ranges, i e., 770±20℃ and 3-5 kb, respectively. Although the sample ITO 11c shows similar temperature, its calculated pressure is close to 0 kb. The bulk and mineral chemistry and the temperature-pressure estimation suggest that the magma reservoir was not distinctly zoned but was very homogeneous throughout prior to eruption.

著者

後藤 芳彦 佐々木 央岳 鳥口 能誠 畠山 信

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.58, no.3, pp.461-472, 2013-09-30 (Released:2017-03-20)

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北海道クッタラ火山登別地熱地域,大湯沼の北東200m地点において,トレンチ調査(深さ6.3m)を行い,登別地熱地域の噴火史を解明した。トレンチ断面の層序は,12層の水蒸気噴火堆積物(厚さ3-100cm)と,それらに挟在するB-Tmテフラ,Us-bテフラからなる。12層の水蒸気噴火堆積物は,変質したデイサイト質石質岩片(最大粒径80cm)と粘土質のマトリクスから構成され,サグ構造を示すことから,登別地熱地域から噴出したと考えられる。各々の水蒸気噴火堆積物は土壌層を挟在し,12回の噴火が休止期を挟んで繰り返し起きたことを示す。水蒸気噴火堆積物の直下土壌層の放射性炭素年代測定値,および広域テフラとの対比により,水蒸気噴火は,約BC6450年,BC5370年,BC3980年,BC3440年,BC1990年,BC1710年,BC1280年,BC900年,BC200年,AD980年,AD1480年,およびAD1663年以降に起きたと推定される。登別地熱地域では,過去8500年間に12回以上の水蒸気噴火が起こり,噴火の頻度は700年に1回程度であると考えられる。

著者

石毛 康介 安田 裕紀 志水 宏行 富島 千晴 大橋 正俊 関根 大輔

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.62, no.1, pp.37-42, 2017-03-31 (Released:2017-03-28)

参考文献数

6