著者
小山 真人 早川 由紀夫
出版者
公益社団法人 東京地学協会
雑誌
地學雜誌 (ISSN:0022135X)
巻号頁・発行日
vol.105, no.2, pp.133-162, 1996 (Released:2009-11-12)
被引用数
11 or 0

We reveal the detailed syn-and post-caldera eruptive history of Izu Oshima Volcano, Japan, by tephra and loess stratigraphy. Twenty-four tephra layers, which overlie the slope outside the caldera, show that 24 eruptions occurred since the formation of the caldera (about 1, 450 years ago). These eruptions are separated by 10-200 years clear dormant periods, which can be identified by eolian dust (loess) interbedded with tephra layers. The 24 eruptions can be classified into three types : 1) eruption with scoria and ash falls (12 eruptions), 2) eruption only with scoria falls (7 eruptions), and 3) eruption only with ash falls (5 eruptions). While tephra discharge mass of the type 1 is generally large (1.5×1010 to 7×1011 kg), that of the type 2 or 3 is small (0.6 ×109 to 1 ×1011 kg). The 1986 eruption is classified into the type 2. Debris avalanches, which occurred just before the caldera formation and covered almost all of the Izu Oshima island, demonstrate that the present caldera wall was formed by slope failure of an old edifice. The tephra-discharge stepdiagram, which shows a relationship between time and cumulative discharge volume / mass of magma, shows : 1) the average tephra-discharge rate is constant (92 kg/ s before the N1.0 eruption and 25 kg/s after the N1.0 eruption), showing an abrupt decrease of the rate at about the time of the N1.0 eruption, which occurred about 900 years ago and was the most voluminous eruption for the past 1, 450 years, 2) both before and after the N1.0 eruption, the type 1 eruption shows volume-predictability, that is, the discharge volume / mass of a next type 1 eruption can be predicted, 3) a type 1 eruption should occur sometime in the future again, and when it occurs, the discharge mass of tephra should attain to as much as 2×1011 kg or more.

言及状況

外部データベース (DOI)

Twitter (28 users, 36 posts, 26 favorites)

小山・早川(1996)伊豆大島火山カルデラ形成以降の噴火史 https://t.co/k6lfrMXHd4
参考(再掲):伊豆大島火山カルデラ形成以降の噴火史 https://t.co/4KMqVPH7lL テフラとレスからみたカルデラ形成以降の伊豆大島火山の噴火史(口絵写真と解説)https://t.co/XXS7gplmpx
続)Nakamura(1960,1964)と一色(1984a) は, 1338年 噴火記事をY5の噴火にあたると考えた。しかし,1338年記事には降灰以外の具体的な記載がないから,この対比には疑問が残る」https://t.co/4KMqVPH7lL
伊豆大島火山カルデラ形成以降の噴火史 https://t.co/EZQHGHswoj

収集済み URL リスト

https://www.jstage.jst.go.jp/article/jgeography1889/105/2/105_2_133/_pdf (25)

https://www.jstage.jst.go.jp/article/jgeography1889/105/2/105_2_133/_article/-char/ja/ (5)