書誌事項
- タイトル別名
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- Magnetization Intensity Distribution in the Western Unzen Region, Kyushu, Japan, Inferred from a Helicopter-borne Aeromagnetic Survey
- ヘリボーン クウチュウ ジキ タンサ カラ スイテイ サレル ウンゼン セイブ チイキ ノ ジカ キョウド ブンプ
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A helicopter-borne, aeromagnetic survey was performed in October 2004 over the western Unzen region, Kyushu, Japan. The survey was flown at an altitude of about 1100m above sea level along north-south survey lines and east-west tie lines, spaced 500m and 1000m apart, respectively. The observed aeromagnetic anomalies were reduced onto a constant surface of 1500m above sea level. Then, a magnetization intensity distribution was estimated, assuming that it varies only laterally. The characteristics of the magnetization intensity distribution are summarized as follows;(1) The hydrothermally altered areas of Unzen hot spring, Ii-Dake, Shimo-Dake, and Kami-Dake show magnetization lows, which indicates that high temperature fluids associated with hydrothermal activities reduce the rock magnetization. These fluids are likely to migrate through E-W trending faults developed inside the Unzen graben.(2) Magnetization lows lie outside of the Unzen graben, corresponding to debris flow deposits and pyroclastic-flow deposits of the Older Unzen (500-150ka). In contrast, magnetization highs are distributed in the northern part region of Azuma-Dake and Hachimaki-Yama and around Takaiwa-Yama, where the lava of the Older Unzen (500-300ka) is exposed. (3) Magnetization lows, corresponding to fan deposits of the Older Unzen (500-300ka), are distributed along the Chijiwa fault.
収録刊行物
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- 火山
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火山 51 (3), 175-181, 2006
特定非営利活動法人 日本火山学会
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詳細情報 詳細情報について
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- CRID
- 1390282679281616896
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- NII論文ID
- 110004751973
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- NII書誌ID
- AN10512786
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- ISSN
- 21897182
- 04534360
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- NDL書誌ID
- 8041524
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- 本文言語コード
- ja
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- データソース種別
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- JaLC
- NDL
- CiNii Articles
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- 抄録ライセンスフラグ
- 使用不可