著者

鈴木 毅彦 早川 由紀夫

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.29, no.2, pp.105-120, 1990

被引用文献数

15 17

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Five distinctive tephra beds (A₁Pm-A₅Pm), carrying abundant biotite and quartz crystals, are widely distributed in central Japan. They are here collectively called Omachi APms or APms in short, and are petrographically identified by high refractive indices of hornblende (n₂=1.685-1.696) and orthopyroxene (γ=1.728-1.737). One bed of the APms is found as far as 239km from the presumed source, Momisawadake in the Hida Mountains, where it is 4cm thick and composed mainly of silt-sized glass. No proximal deposit made up of coarse pumice fragments is found owing to unfavorable preservation of the mountainous landscapes; however, the eruption style is supposed to be of plinian type based on analyses of grain size along the dispersal axis.<br>Assuming that the accumulation rate of loess soil has been constant at each locality, the age of APms is estimated 0.24-0.33 Ma by the overlying soil thickness. Moreover, in the south Kanto district, one of the APms is intercalated between two well-established marker-tephra: GoP (0.25-0.30Ma) and TE-5 (0.35-0.40Ma). It is very likely that the age of APms is 0.30-0.35Ma. The time interval between A₁Pm and A₅Pm eruptions is estimated to be less than 0.05Ma, because the thickness of the soil layer intercalatcd between APms does not exceed 106cm at any locality.<br>The Omachi APms are found on the flanks and slopes of many volcanoes in central Japan, such as Azumaya, Yatsugatake, Kusatsu Shirane, and Takahara. They are also found among deposits forming fluvial terraces in north Kanto. The significance of APms as Middle Pleistocene time-markers will be established hereafter.

著者

早川 由紀夫

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.38, no.6, pp.223-226, 1993-12-20

被引用文献数

4 9

著者

早川 由紀夫 藤根 久 伊藤 茂 Lomtatize ZAUR 尾嵜 大真 小林 紘一 中村 賢太郎 黒沼 保子 宮島 宏 竹之内 耕

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.120, no.3, pp.536-546, 2011-06-25 (Released:2011-09-06)

参考文献数

11

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Two wood trunks, one charred and 75 years old and the other not charred and more than 199 years old, were collected from Hayakawa ignimbrite of Niigata Yakeyama Volcano. They were investigated using the radiocarbon wiggle-matching method to determine the age of the eruption. The result was 1225-1244 cal AD (95.4%), which is over 200 years younger than previous estimates. The eruption, including the Hayakawa ignimbrite, was the largest during the volcano's life period of 3000 years. Co-ignimbrite fallout KGc ash has been found at many archaeological sites spreading on the eastern flanks of Myoko Volcano and the Takada Plain. The age obtained here will provide a useful time constraint for archaeologists and volcanologists studying this area.

著者

早川 由紀夫

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.40, no.3, pp.211-212, 1995-07-31

著者

早川 由紀夫 小山 真人

出版者

群馬大学

雑誌

特定領域研究

巻号頁・発行日

2005

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中学1年で学ぶ「大地の変化」のうち、火山に関する部分の学習プログラム(全9時間)をつくって授業実践した。1時間目:火山噴火とは2時間目:火山噴出物とマグマ3、4時間目:火山の形、溶岩の色、噴火の様子とマグマ5時間目:火山がつくる地形・地層と人間生活6、7時間目:火成岩と鉱物8時間目:火山の災害と恵み9時間目:火山について調べよう当初計画していた地震と地層については、教材をいくつか作成するに留まり、学習プログラムをつくるまでには至らなかった。作成した火山学習プログラムには、ITを利用したデジタル教材を多用した。デジタル教材はリアルでわかりやすい表現を可能にしただけでなく、これまでできなかった新しい表現方法も生み出した。しかし、デジタル教材だけで学習プログラムを作成してもよい授業ができないことがわかった。従来のアナログ教材にも捨てがたい長所がある。古くからある教材に工夫を加えて使ったり、独創的なアイデアで新しい教材を開発するなどしてアナログ教材も使い続けるべきである。両者を併用して、バランスの取れた学習プログラムを作成するのが望ましい。本研究で新規作成あるいは改良した教材のうち主なものは次のとおりである。アナログ教材:コーラ噴火、減圧発泡、カルメ焼き、弁当パック立体模型、かざんきっずデジタル教材:カシミール3D、ウェブ紙芝居(立体地形編、自然史編、おはなし編)、噴火勤画、かざんくいず、噴火カタログ、噴火史料データベース、浅間山の北麓地質図、浅間山の火山灰を測ろう、オーロラカメラ、地震波シミュレーション

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

被引用文献数

4

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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

早川 由紀夫 井村 隆介

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.36, no.1, pp.25-35, 1991-04-15 (Released:2017-03-20)

被引用文献数

1

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The eruptive history of Aso volcano for the past 80,000 years is revealed by tephrochronology and loess-chronometry. Around the Aso caldera is a thick accumulation of loess, which is intercalated with numerous Aso tephra layers of limited dispersal as well as three widespread tephra layers of known age that are good marker horizons ; the Akahoya ash (6.3 ka), the Aira-Tn ash (22 ka), and the Aso-4 ignimbrite (70 ka). Loess-chronometry is based on the assumption that, in the Aso region, the accumulation rate of loess has been constant as 12 cm/ky from 80 ka to the present. Most of tephra layers after the caldera-forming Aso-4 eruption are composed of volcanic sand or scoria lapilli of basaltic andesite composition. However the 27 ka Kusasenri dacite (SiO2 = 67%) pumice is a conspicuous exception. The large volume of 5.85 km3 (bulk) and wide dispersal of this pumice suggests that it is a product of plinian eruption. From October 5 to the end of November 1989, the Nakadake crater of Aso volcano was in eruption. Ash was uninterruptedly emitted from a 500-1,000 m high eruption column coming out of the crater. The average discharge rate of ash was 5 × 107 kg/day. The total mass of ash discharged during the two months reached 3 × 109 kg. The penultimate eruption in recent history was June-August 1979, when 7.5 × 109 kg of ash was discharged. Outside the Aso caldera, the thickness of the 1989 ash is less than 1 cm. It is almost impossible to detect an old ash layer of thickness about 1 cm in a loess cross section, suggesting that sedimentary records 10 km away from a volcano are insufficient to reconstruct past eruptions smaller than 1010 kg. Eruptions smaller than 1010 kg can be determined only from proximal deposits. The history of eruptions of Aso volcano over the last few thousand years is tentatively determined from cross sections 2-4 km west of the Nakadake crater. After a 580-1,250 year dormant period, Aso volcano became active about 1,780 years ago. From then, small eruptions each with 109-1010 kg ash discharge have been repeated 48-88 times up to the present. The duration of each eruption was a few months, and the dormant interval between eruptions averaged 20-37 years.

著者

早川 由紀夫

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.107, no.3, pp.444-457, 1998-06-25 (Released:2009-11-12)

参考文献数

18

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ハワイ島はハワイ諸島最大の島で, 群馬県と埼玉県を合わせたくらいの面積をもつ。活発に噴火を続けるキラウエアのほか, 歴史時代に噴火記録があるマウナロアとフアラライ, 4,205mの山頂まで車で行くことができるマウナケア, 山頂近くまで深い谷に刻み込まれたコハラ, の5火山からなる火山島である (図1) 。ハワイ・ホットスポットの火山活動を観察するのに最適の島だ。オアフ島のホノルルから直行便が, 東海岸のヒロと西海岸のコナへ毎日数便飛んでいる。私たちはキラウエアに近いヒロへ飛ぶことにしよう。アメリカのレンタカーは一週間単位で借りると割安だから, ハワイ島に7泊する旅行計画を立てるとよい。40ドルの乗り捨て料金を負担すれば, ヒロ空港で借りた車をコナ空港に返すこともできる。実際, 私は11人の仲間といっしょに1997年12月24日にヒロ空港に降り立ち, 南回りで移動して, 12月31日早朝コナ空港から帰国の途についた。この火山見学案内は, そのときの体験と, 過去3回の私自身のハワイ島旅行経験 (1983年, 1987年, 1991年) に基づいて執筆したものである。出発当日に旅行代理店の倒産を知らされるという困難を克服して, 9日間の旅行を実り多く, しかも楽しく終えることができたのは, 旅行に参加した群馬大学教育学部学生と卒業生みなさんの力による。なお, 旅行参加者全員の分担執筆による体験記をウェブページ (http://www.edu.gunma-u.ac.jp/~hayakawa/fieldguide/p/US/HI/hawaii 97.html) で公開している。これから現地に行く人に利用していただけたら幸いです。

著者

早川 由紀夫

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.40, no.Special, pp.S1-S15, 1995-12-25 (Released:2017-03-20)

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Age of a tephra can be determined by simple stratigraphy, if adequate number of time-markers are provided. Eleven master tephras are chosen as the time-markers for the last one million years. They are Kikai-Akahoya (7.330 ka), Aira-Tanzawa (26.00 ka), Daisen-Kurayoshi (50.00 ka), Aso-4 (87.00 ka), Ata-Torihama (250.0 ka), Kakuto (340.0 ka), Suiendani-TE5 (420.0 ka), Kobayashi-Sakura (540.0 ka), Kaisyo-Toriitoge (650.0 ka), Shishimuta-Azuki (870.0 ka), and Shishimuta-Pink (1000 ka). The present earth surface and Bruhnes/Matuyama boundary (780.0 ka) play a same role as master tephras. Ages of some master tephras are assigned rather arbitrarily, however, it is productive to affix them once to a specific value. A tephra sandwiched between two master tephras is afforded its age by interpolating the thicknesses of loess between them. This technique, loess-chronometry, has the advantage of ability to measure an interval of tens to thousands years in the geologic past, over radiometric dating. More than 900 tephras are presently recorded and linked each other in a computer database including name, source volcano, age, magnitude, stratigraphy, and remarks. An updated version is listed in WWW at "http://www.la.gunma-u.ac.jp/〜hayakawa/English.html".

著者

早川 由紀夫

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.36, no.3, pp.357-370, 1991-10-15

被引用文献数

4

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The recent progress of physical volcanology is reviewed focusing on studies on volcaniclastic flows and their deposits. Pyroclastic flows are high-particle-concentration, laminar currents with gas as a continuous phase. Pyroclastic surges are low-particle-concentration, turbulent currents with gas as a continuous phase. Lahars are flows of debris with liquid water as a continuous phase. Debris avalanches are catastrophic landslides in which a continuous phase is absent or plays no role for the motion. Owing to the upward gas flow, fluidization processes operate in pyroclastic flows. Flow behavior and resultant deposits are remarkably different depending the degree of fluidization, because it effectively reduces the yield strength of the flow. However, the distance traveled is slightly affected by the degree of fluidization. It is determined mainly by the mass incorporated at the source or by the velocity acquired when it wes initiated.

著者

早川 由紀夫 由井 将雄

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.28, no.1, pp.1-17, 1989

被引用文献数

5 23

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The eruptive history of the Kusatsu Shirane volcano is well described by means of 14 beds of key tephra and intercalating loess soil. Three eruptive stages are recognized. During early or middle Pleistocene the Matsuozawa volcano was formed; this is the first stage. The second stage was initiated by effusion of the Horaguchi lava, which was followed by eruptions of the Oshi pyroclastic flow, older lava flows, 3P pumice fall, and Yazawahara pyroclastic flow. Brown loess soil about 10m thick covering these deposits indicates that a dormant period of more than 100, 000 years followed this stage. The summit area upheaved about 400m or more against the foot of the volcano during this period, as is suggested by the extraordinarily steep (6.1°-3.0°) surface of the Oshi ignimbrite plateau. The third stage, which started about 14, 000 years ago, is the formation of three pyroclastic cones on the summit and contemporaneous effusion of the younger lava flows, <i>e. g.</i> the Kagusa lava of 7, 000 years ago and the Sessyo lava of 3, 000 years ago. In historic times, phreatic explosions have frequently occurred on the summit crater, Yugama. This means that the present belongs to the third stage. It is unlikely that eruptions of the third stage are caused by cooling of the magma chamber which was active in the second stage. The activity of the third stage seems to denote arrival of a new magma chamber at shallow depth.

著者

早川 由紀夫 荒牧 重雄 白尾 元理 小林 哲夫 徳田 安伸 津久井 雅志 加藤 隆 高田 亮 小屋口 剛博 小山 真人 藤井 敏嗣 大島 治 曽屋 龍典 宇都 浩三

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, pp.S208-S220, 1984-12-28

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Stratigraphy and thickness distribution of the pyroclastic fall deposits formed during the eruption of Miyakejima volcano on October 3-4, 1983, were studied immediately after the deposition. Of the total mass of 20 million tons erupted, 8.5 million tons were ejected as basaltic scoria to form a complex set of air-fall deposits east of the fissure vents. One million tons of the latter were ejected from the upper fissures as fire-fountain products. The rest was the product of phreatomagmatic explosions which occurred in the lower fissures where ground water chilled the magma to form dense scoria blocks which devastated villages. Explosion craters and a tuff ring were formed along the N-S trending lower fissures. Account of the general distribution of the deposits, nature of the constituents, mutual stratigraphic correlation and correlation with observed sequence are given.

著者

早川 由紀夫

出版者

日本自然災害学会

雑誌

自然災害科学 (ISSN:02866021)

巻号頁・発行日

vol.26, no.1, pp.6-11, 2007-05-31

著者

早川 由紀夫 萩原 佐知子 野村 正弘 小山 真人

出版者

日本地図学会

雑誌

地図 (ISSN:00094897)

巻号頁・発行日

vol.53, no.1, pp.57-65, 2015

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<p>We have intended to popularize geological maps, which are restricted professional uses presently. Two geologists, a map designer, and a print coordinator worked together to publish two maps at Asama Volcano and five maps in Izu Peninsula. They are easy to read for everyone because topographic relief is used as a base map. Every map was finished beautiful enough you want to exhibit it on the walls. We sell those maps not only at local shops but through the Internet for 500 yen, a surprisingly lower price than existing geological maps.</p>

著者

井上 雄斗 早川 由紀夫 早川 由紀夫 HAYAKAWA Yukio

出版者

群馬大学教育学部

雑誌

群馬大学教育学部紀要. 自然科学編 = Science reports of the Faculty of Education, Gunma University (ISSN:00175668)

巻号頁・発行日

vol.67, pp.21-37, 2019

著者

早川 由紀夫

出版者

東京大学

巻号頁・発行日

1985

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博士論文

著者

早川 由紀夫 中村 賢太郎 藤根 久 中村 賢太郎 ナカムラ ケンタロウ Nakamura Kentaro 藤根 久 フジネ ヒサシ Fujine Hisashi 伊藤 茂 イトウ シゲル Ito Shigeru 廣田 正史 ヒロタ マサシ Hirota Masashi 小林 紘一 コバヤシ コウイチ Kobayashi Koichi

出版者

群馬大学教育学部

雑誌

群馬大学教育学部紀要. 自然科学編 = Science reports of the Faculty of Education, Gunma University (ISSN:00175668)

巻号頁・発行日

vol.63, pp.35-39, 2015

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Radiocarbon wiggle matching method was applied for precise dating of a tephra which was designated asone of the important key beds for archaeology. The FA tephra is a pyroclastic deposit from the Shibukawaeruption of Haruna Volcano during the Kofun period of Japan. The age of FA has been investigated usingarchaeological remains and also historical records of Japan and China. It has been estimated roughly as early6th century. Three tumbled logs were found being buried in the tephra whose thickness was about 4 m. Thelogs were cut in many groups with five tree rings and every two groups were sampled for C measurement. Asthese trees were thought to have the same age from the occurrence,all data were used for wiggle matchinganalysis. The age of the outermost tree ring group is determined as AD 491-500(AD 497/+3/-6).

著者

早川 由紀夫 ハヤカワ ユキオ Hayakawa Yukio

出版者

群馬大学教育学部

雑誌

群馬大学教育学部紀要. 自然科学編 = Science reports of the Faculty of Education, Gunma University (ISSN:00175668)

巻号頁・発行日

vol.62, pp.35-50, 2014

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2011年3月11日に起こった大きな地震と津波のあとしばらくして、大量の放射性物質が福島第一原発から大気中に出た。私はその汚染分布を迅速に把握して地図に表現し、インターネットで即座に公表した。放射性物質は原発から連続的定常的に放出されたのではなかった。3月12日、3月15日、それから3月20-21日に大きな放出イベントがあった。原子炉格納容器の圧力が低下あるいは上昇したときに対応する。順に1号機、2号機、3号機からの放出だった。大気中に出たセシウムは1京1000兆ベクレル(11PBq)。1986年のチェルノブイリ原発事故で出たセシウムの1/12である。しかし人口密度を考慮すると、被害は両者ほぼ同じかフクシマが3倍深刻である。芝生や森の林床だけでなく、アスファルトの上でも2011年3月に降り積もったセシウムはほとんど移動していない。そういった場所の放射線量率の自然減衰はセシウム134と137の半減期でよく説明できる。この事故で放出されたセシウムに起因するがん死の増加は5300人と見積もられる。今後50年間の福島中通りにおける放射能リスクは交通事故リスクの1/2である。

著者

飯塚 雅哉 早川 由紀夫 IIDUKA Masaya HAYAKAWA Yukio

出版者

群馬大学共同教育学部

雑誌

群馬大学共同教育学部紀要. 自然科学編 = Science reports of the Cooperative Faculty of Education, Gunma University (ISSN:00175668)

巻号頁・発行日

vol.69, pp.13-26, 2021

著者

早川 由紀夫

出版者

古今書院

雑誌

地理 (ISSN:05779308)

巻号頁・発行日

vol.65, no.1, pp.4-11, 2020-01