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タイトル: 13. Gravity Surveys on Aso and Kuju Volcanic Region, Kyushu District, Japan
その他のタイトル: 13.阿蘇及び九重火山地域の迫力測定
著者: Kubotera, Akira
Tajima, Hirokazu
Sumitomo, Norihiko
Doi, Hikaru
Izutuya, Sadakatu
著者(別言語): 久保寺, 章
田島, 広一
住友, 則彦
土居, 光
井筒屋, 貞勝
発行日: 1969年7月31日
出版者: 東京大学地震研究所
掲載誌情報: 東京大学地震研究所彙報. 第47冊第2号, 1969.7.31, pp. 215-255
抄録: Gravity survey at 446 points in an area of about 4300km2 over the Aso and Kuju volcanic region occupying the central part of Kyushu Island of Japan was made by use of Worden and LaCoste and Romberg Geodetic Gravimeters from 1965 to 1966. This survey was carried out as one of the branch projects of "Combined Aeromagnetic-Gravity Studies of Calderas in Japan". Bouguer gravity anomalies over this area are characterized by 1) a strong negative anomaly on the Aso caldera, 2) a circular negative anomaly over the Kuju volcano group on the north-eastern side of the Aso caldera, 3) positive anomalies on the south-western flank of somma of the Aso caldera and 4) a narrow belt of relatively high gravity running from Ooita to Kumamoto. The gravity low of the Aso caldera shows characteristic feature of the "low anomaly type caldera" as is pointed out by Yokoyama. The Kuju volcanic group also shows the similar feature of "low anomaly type caldera", though existence of caldera is not identified from topographical view point. This fact coincides with the geological presumption of buried existence of the Kuju caldera which was once as gigantic as that of the Aso caldera. On the south-western flank of the somma of the Aso caldera, the oldest formation consists of semi-shist (Sambagawa System) and the outcrop of basalt is also being found from geological surveys. The gravity high which reaches 22 mgal at the center coincides with the distribution of basaltic formation. It reveals, therefore, the high density material such as basaltic or metamorphic rocks. A narrow belt of relatively high gravity is remarkably observed. The tectonic line which is geologically presumed to run from Ooita westward to Kumamoto through the Kyushu Island just coincides with this belt.|阿蘇及び九重火山地域を含む,約4300平方キロメートルの面積における重力測定結果について述べる.この研究は,日米科学応力の一環として行われた研究「日本火山カルデラの航空磁気重力測量」の一部をなすものである.
URI: http://hdl.handle.net/2261/12458
ISSN: 00408972


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