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标题：Gravity structure of Akan composite caldera, eastern Hokkaido, Japan: Application of lake water corrections
其他标题：Gravity structure of Akan composite caldera, eastern Hokkaido, Japan: Application of lake water corrections
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作者：Takeshi Hasegawa ; Akihiko Yamamoto ; Hiroyuki Kamiyama 等
期刊名称：Earth, Planets and Space
电子版ISSN：1880-5981
出版年度：2009
卷号：61
期号：7
页码：933-938
DOI：10.1186/BF03353205
出版社：Springer Verlag
摘要：Akan volcano, eastern Hokkaido, Japan, is characterized by a rectangular-shaped caldera (Akan caldera: 24 km by 13 km) with a complex history of caldera-forming eruptions during the Quaternary. A new Bouguer anomaly map of the caldera is presented on the basis of a gravity survey around Akan volcano. As part of and in addition to this survey, we applied gravimetry over the frozen caldera lake including lake water corrections. The Bouguer map shows the distribution of at least three sub-circular minima indicative of multiple depressions inside the caldera. Lake water corrections, performed by a numerical integration method using rectangular prisms, sharpen edges of the sub-circular minima. This gravity feature is consistent with geological investigations suggesting that caldera-forming eruptions of Akan volcano occurred from at least three different sources. It is concluded that Akan caldera can be described as a composite caldera with three major depressed segments.
关键词：Gravity anomaly ;Akan volcano ;composite caldera ;lake water correction