Geological Investigations on the Zao Volcanoes : I. Goshiki-dake, a Central Cone of the Zao Proper.
スポンサーリンク
概要
- 論文の詳細を見る
(i) Goshiki-dake is a central cone of the Zao proper and rises up to 1674 meter above the sea level. It is formed within the semi-circular explosion crater surrounded by Kumano-dake, Umanose, Katta-dake and Haizuka-yama. (ii) This central cone rests upon the eroded surface of lava flows and ejecta which have their sources in the pre-existing crater destroyed largely by later explosions, being deeply dissected and highly cliffed along the Osawa and at the eastern side of Okama. It has a diameter of more than 1000 meters at its base and is about 200 meters high above the bottom of the Osawa. (iii) The central cone is chracterized by the presence of explosion cratercalled generally "Okama" which is found at dts western side. It is a nearly circular depression about 300 meters in diameter, being now filled with beautifully-colored water. (iv) The internal structure is well shown along the crater wall and high cliff dissected deeply by the Osawa. The cone is built up of ash, sand, lapilli and agglomerate which are distinctly stratified and incline to the west at an angle of 10°-15°. They have accumulated alternately with no intercalation of lava flows. The surface of the central cone and its surrounding area are largely veiled with recent ejecta thrown out from Okama. They are composed of ash and lapilli, the prevailing color being light grey or grey. (V) Volcanic sand and ash here consist of plagioclase, augite, hypersthene and magnetite as well as of tuffaceous substances and minute fragments of two pyroxene andesite. The recent lapilli is, however, represented by two pyroxene andesite subjected mostly to solfataric action. Agglomerate contains angular or subangular fragments of two pyroxene andesite with such component minerals as labradorite, bytownite, augite, hypersthene, magnetite and brown glass. (vi) The volcanic activities of the central cone are recorded since 884. The most recent one took place in 1939. So far as is shown by historic records, these activities always took place in Okama, and the explosion was frequently followed by the inundation of lake water which caused a serious damage to the district along the Nigori-gawa, Matsu-kawa, Shiroishi-gawa, etc. The fumaroles newly opened in 1940 are still active at present, their exhalation being composed mainly of superheated steam with a small amount of SO2. In conclusion, the writer's thanks are due to Dr. H. Tsuya who allowed him to continue his work in the Earthquake Research Institute of Tokyo University. The writer is also deeply indebted to Mr. R. Morimoto and Mr. F. Hori for their co-operation in his laboratory work. The expense of this research was defrayed from the fund for the Scientific Research of the Educational Ministry.
- 1951-08-30
論文 | ランダム
- Bi_2Te_3の電子構造とゼーベック係数
- 基調講演 民生技術への移行と日本の役割 (第9回自由民主党軽井沢セミナ--2-) -- (第3分科会 科学技術--優れた民主技術を活用し世界に貢献〔含 質疑応答〕)
- 基調報告 「暫定の時代」から本格的な情報化時代を迎える (第6回自民党軽井沢セミナ---国際国家・日本の課題-2-) -- (第3分科会 高度情報社会--インテリジェント国家の構築〔含 質疑応答〕)
- 第3分科会 高度情報社会の課題 (第四回軽井沢セミナ- 日本の課題と指針)
- 八犬士論のための序論、毛野の成長--八犬伝第三部、仁と智による犬士像完成へ