Recursos de colección

Hokkaido University Collection of Scholarly and Academic Papers (135.521 recursos)

HUSCAP (Hokkaido University Collection of Scholarly and Academic Papers) contains peer-reviewed journal articles, proceedings, educational resources and any kind of scholarly works of Hokkaido University.


Mostrando recursos 1 - 14 de 14

  1. 火山岩塊の運動再考(2)- 放出火山岩塊の空気抵抗と爆発主軸の傾き効果 -

    鈴木, 建夫; 新井田, 清信; 西田, 泰典; 大島, 弘光; 室伏, 誠
    The present authors pointed out, in the last paper, a mistake in the equation of motion for volcanic blocks. Reliable assumption of the air resistance to the blocks is required for accurate estimation of initial velocity of volcanic blocks. However, little attention has been given to the point. This paper organizes the problems about the estimation of the air resistance and proposes a new method of the estimation. Also this paper organizes the effect of factors on the distribution of volcanic blocks. Model calculations revealed the effect of the atmospheric air density cannot be ignored. For the effect of explosion...

  2. 火山岩塊の運動再考(1)- 放出火山岩塊の運動方程式 -

    鈴木, 建夫; 新井田, 清信; 西田, 泰典; 大島, 弘光; 室伏, 誠
    Many authors have discussed the eruption time sequence and the mechanism of volcanic eruptions by estimating the ejected velocity of the volcanic blocks, with the aid of other factors of eruptive phenomena. Equations of motion for the volcanic blocks have been proposed by considering the factors, such as the air resistance, the influence of the wind, the inclination of the explosion principal axis and so on. However, the equation of motion and its solution has not been considered that the air resistance power was vector quantity for the flight of volcanic blocks. In this paper a new equation of motion...

  3. 1977 年有珠山噴火で生じた噴煙柱の解析

    小野, 忍; 大島, 弘光
    The 1977 eruption of Mt.Usu generated four high-altitude eruption columns which produce BIGⅠ,BIGⅡ,BIGⅢ and BIGⅣ tephra-fall deposits respectively. Expressing the initial eruption velocity in terms of the solid mass eruption rate, the initial temperature, the initial radius and the initial gas fraction from the conservation of solid particles, we apply a steady plume model to the four eruption columns. The initial velocity increases with initial gas mass fraction and initial temperature for the solid mass eruption rate estimated from the volume of deposits, the apparent density of tephra and the eruption duration. For three eruption columns depositing BIGⅠ,BIGⅡ and BIGⅢ,...

  4. 有珠山自然電位観測2006

    長谷, 英彰; 橋本, 武志; 西田, 泰典; 宇津木, 充; 井上, 寛之; 佐波, 瑞恵
    We conducted self-potential (SP) surveys on Usu volcano since July to December 2006. The compiled SP map reveals positive anomalies around Ko-Usu lava dome and at the foot of the volcano, and a negative anomaly on the top of O-Usu lava dome. The SP profile on the summit caldera shows the same pattern of 1985’s. However, the peak-to-peak variation of the SP value is different: the 1985’s of that shows 1000 mV while the 2006’s shows 1400 mV. Topographic effect is clearly shown along the southwestern foot of the volcano, in which coefficient is about -2.5 mV/m. The SP profile...

  5. 広域水準測量から見た北海道駒ケ岳の深部マグマ溜まり

    森, 濟
    Mt. Hokkaido-Komagatake is located at the southwestern part of Hokkaido and one of the most active volcanoes in Japan. The volcano had made one of the largest eruptions in the 20th century in Japan. But the usual seismic activity of the volcano is extremely low, and only few earthquakes observed before the each small phreatic eruption in 1996, 1998 and 2000. Wide area and long range geodetic measurements, therefore, are important to infer the long term activity of the volcano. The first order leveling survey, which is administered by Geographical Survey Institute Japan, is the only one geodetic method having...

  6. 放熱率測定に基づいた有珠2000年噴火の活動推移長期予測

    後藤, 章夫; 鍵山, 恒臣; 宮本, 毅; 横尾, 亮彦; 谷口, 宏充
    The energy source of volcanic activity is the heat of magma. Heat discharge rate on the initial stage of Usu 2000 eruptive activity was estimated to be around 1×109 J/sec, that was over one order higher than that on the initial stage of the 1977 activity, and comparable to its peak release rate observed after two years from the beginning of the eruptive activity. Compare to the 1977 activity, much shorter duration of the 2000 activity may be the result of rapid cooling of the intruded magma. Abundant ground water supplied from Lake Toya might remove the heat effectively through...

  7. 2004 年留萌支庁南部地震震源域の重力測定

    本多, 亮; 神山, 裕幸; 山口, 照寛; 市原, 寛; 茂木, 透
    An earthquake (MJMA 6.1), occurred in December 14, 2004, at southern area of Rumoi sub-prefecture, northern Hokkaido, Japan. The earthquake intensity was assumed to 6 in Obira town. In Hokkaido, this is the first inland earthquake larger than M6 since Teshikaga earthquake (MJMA 6.5, 1967). Detailed aftershock distribution shows that the aftershocks occur on an eastward dipping plane of 10 km square, depth of which 5 km. The mainshock assumed to have occurred near the southern end of this plane. Despite the sparseness of existing gravity stations over the focal region, it was found that the aftershocks occur just above...

  8. ドーム状隆起に伴う磁場変化 ―有珠山2000 年噴火時の全磁力変化再検討―

    橋本, 武志; 茂木, 透; 西田, 泰典; 高田, 真秀; 鈴木, 敦生; 前川, 徳光; 佐藤, 秀幸
    We investigated geomagnetic changes due to dome-like deformation by using a truncated circular cone model. In the case of the normal magnetization, magnetic total field decreases in the northern side of the uplift center, while it increases in the southern side. We found that the original topography prior to the mound formation does not affect the pattern of this magnetic change. We then apply this calculation to the mound-forming activity in the 2000 eruption of Usu Volcano to infer the magnetic change on the foot of the mound. The expected range of magnetic total field change at the station U01...

  9. 極域電離圏上部におけるイオン上昇流の観測

    佐藤, 創我; LIU, Huixin; 渡部, 重十; 小川, 泰信
    Ion upflow has been investigated by use of ESR (EISCAT Svalbard Radar), SuperDARN, ACE satellite and CHAMP satellite. The field-aligned ion upflows were observed by ESR, which occurred in night-time between 16 and 17, April 2002, and 19 June 2004. However, ESR didn’t show remarkable increase of electron density, electron temperature and ion temperature, which are generated by auroral particle precipitation or frictional heating. The Solar wind parameters were obtained by ACE satellite. SuperDARN showed variation of convection electric field depending on By component of Interplanetary Magnetic Field. CHAMP satellite observed also variations of neutral density, neutral wind, ion density...

  10. 臨時稠密地震観測で見えてきた有珠山の微小地震活動

    青山, 裕; 鬼澤, 真也; 為栗, 健; 鈴木, 敦生; 前川, 徳光; 大島, 弘光; 森, 濟; 橋本, 武志; 志賀, 透; 小山, 寛; 中橋, 正樹; 吉川, 章文; 福山, 由朗
    We performed temporary dense observation at Usu volcano in summer 2006, aiming to reveal micro-earthquake activity under the summit crater during dormant period of the volcanic activity. During about 80 days of temporary observation, more than 330 volcanic earthquakes were observed. Of these earthquakes, well-recorded 142 events are selected for relocation analysis assuming the 3D-velocity structure model which is a result of the explosion seismic experiment at Usu volcano in 2001. Following the result of relocation, we estimated focal mechanism of 7 earthquakes whose magnitudes are more than 1.0. The temporal observation and analyses gave us three new insights about...

  11. 数値シミュレーションによる薩摩硫黄島硫黄岳の火山熱水系の考察

    松島, 喜雄
    The thermal activity of Iwodake volcano is characterized by the predominant volcanic gas ejection at the summit crater and the heat discharge from high ground temperature area which is distributed widely from the summit crater to hillside of the mountain. The volcanic gas at the summit crater is of magmatic origin and its temperature is observed to be 880°C in maximum. The total amount of the volcanic gas discharged from the summit area is estimated to be 150kg /sec from the SO2 measurement and the chemical composition of the volcanic gas. The heat discharge rate form the high ground temperature...

  12. 北海道における地殻,上部マントルの熱的構造:総合報告

    西田, 泰典; 橋本, 武志
    Many researchers have studied the thermal state of the crust and the upper mantle and its tectonic implications in Hokkaido, Japan. Terrestrial heat flow data have revealed the following characteristic features: (1) High heat flow (84〜125 mW/m2) is observed in the backarc side of the volcanic front, while low heat flow (< 42 mW/m2) is observed in the forearc side, showing the typical thermal aspects of the island arc. (2) The central axis zone of Hokkaido (the Kamuikotan and Hidaka metamorphic belts) shows relatively low heat flow (42〜80 mW/m2). The low heat flow zone extends for Sakhalin. (3) Extremely low...

  13. 岡田 弘教授記念号の発刊に際して

  14. 地球放射線帯の動径拡散モデルの構築

    小松, 研吾; 渡部, 重十
    The radiation belts are the region that energetic charged particles are trapped by Earth’s magnetic field. It is well known that the energetic particles flux are varied during geomagnetic disturbances. Many researchers have studied about the flux variation of radiation belt, but the mechanism of the variation has not been understood in detail. A radial diffusion model can reproduce a basic structure of the radiation belts. Radiation belt particles are supplied from the outer boundary of the radiation belt, and the flux is arranged by the balance of intensity of the diffusion and the loss due to pitch-angle scattering. An...

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