著者

澤田 可洋

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.111, no.3, pp.374-394, 2002-06-25 (Released:2009-11-12)

参考文献数

44

被引用文献数

8 7

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The detection rate of eruption cloud with Geostationary Meteorological Satellite (GMS ; HIMAWARI in Japanese) is 12.1%, but GMS can detect and track, at a high rate of 81.5%, eruption cloud from a large explosive eruption higher than 10 km which may threaten aviation safety.Estimates of the top altitude of eruption clouds within the tropopause based on cloud-top temperature show fairly high values compared to those obtained by ground observations. Growth of vapor clouds over eruption clouds induced by strong ascending currents with eruption-onset may be the reason.Apparent dislocation of eruption clouds on GMS images due to the parallax of GMS is clarified for the case of the 1986 Izu-Oshima Eruption, Japan, and the underestimation of cloud-top is possibly due to warming of the cloud-surface by radiation from internal hot material.From inspections of the pattern of cloud-extent, type, strength, decay, and duration of eruption activity can be evaluated.Differential Thermal Infrared Imagery of GMS-5 is very effective for discriminating ashbearing cloud from ambient atmospheric cloud, but cannot clearly separate an eruption cloud with an extremely high content of water-vapor with phreatic/phreatomagmatic eruption.

著者

澤田 可洋 涌井 仙一郎 小宮 学

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.27, no.3, pp.195-202, 1982

被引用文献数

4

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Atmospheric pressure waves generated by the big eruption of Mount St. Helens at 15 32 GMT on May 18, 1980 are recorded with microbarographs at eight stations of Japan Meteorological Agency in Japan of about 7, 000-9, 000 km in great circle distance from the volcano. The wave train is also detected with World Wide Standard Seismograph (long period and vertical component) settled at Matsushiro, Nagano Prefecture. It is the third time since the 1883 Krakatau Eruption and the 1956 Bezymianny Eruption that atmospheric pressure waves caused by volcanic eruptions at long distance are recorded with barograph or micrographs in Japan. The barograms of atmospheric pressure waves begin with increase of atmospheric pressure and distinct waves which give the maximum amplitude of 3-5 minutes of period. The mean of the maximum amplitude of records is 0.10 mb and the mean propagation velocity 308 m/sec. The antipodean wave train (A₂) and the third one (A₃) are not detected. The estimated energy of the eruption by applying the results by HUNT et al. (1960) and WESTON (1961) is at least 10²³ ergs. This estimated energy almost coincides to the energy of the 1956 Bezymianny Eruption estimated by MURAYAMA (1969). It would not be appropriate to directly compare with the kinetic energy of the eruption estimated through the amount of ejecta, but the above-mentioned estimated energy is almost same order of the mechanical energy of the blast according to DECKER R. and DECKER B. (1981). Comparing with records of atmospheric pressure waves detected in the United States, West Germany and the Netherlands, the maximum amplitude of barograms obtained in Japan is less about 10%. This may be caused by prevailing westward winds in the upper atmosphere on the propagation path from Mt. St. Helens to Japan, but the remarkable difference of propagation velocity is not seen.

著者

澤田 可洋 Andal C. Marzan D.

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.25, no.4, 1980-12-01

著者

澤田 可洋

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.21, no.3, 1976-12-15