暖かい対冷たい沈殿変異の地震的影響:日本の南西と北東からの例
1Department of Geology, Arizona State University, Tempe, AZ 85287-1404, USA. Pacific Geoscience Centre, Geological Survey of Canada, Sidney, BC V8L 4B2, Canada.
Science (New York, N.Y.)
|November 5, 1999
まとめ
サブドクションゾーンは温度によって変化し,地震活動や火山活動に影響を与えます. 日本南西部のような暖かい地域では,海殻の明確な変形反応のために,浅い地震と火山活動が少なくなります.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- ペトロロジー・ペトロロジーとは
- 地震学 地震学とは
背景:
- サブドクションゾーンは,地震性,地震構造,および弧マグマティズムの変動を示しています.
- これらの変異は,海殻を浸透させる海洋内での変異反応と関連しています.
- 日本南西部と日本北東部は,対照的な潜水地帯環境を表しています.
研究 の 目的:
- サブドクションゾーン間の熱差異を調査するために.
- これらの熱変化と,観測された地震性および弧磁気性の違いを相関させるため.
- 海洋地殻の沈殿で起こる変形反応をモデル化するために.
主な方法:
- 日本南西・北東における地震性および弧火山性の比較分析.
- 熱石油学モデルの開発と応用.
- エクロギット変換と脱水を含む変異反応のモデリング.
主要な成果:
- 日本南西部の地殻は,日本北東部の地殻より300~500°C暖かくなると予測されています.
- 温度の上昇は,より浅い水域でのエクロジットの変容と脱水反応につながります.
- イントラスラブ地震は,日本南西では65kmの深さに達し,日本北東では200kmに達する.
- 日本北東部と比較して,日本南西部のアルク火山は稀です.
結論:
- 温度は,海洋地殻を沈殿するメタモルフィック反応を制御する重要な要因です.
- サブドクションゾーンの熱変動は,地震性の深さと弧マグマティズム強度に直接影響します.
- 薄い融解は,より暖かい潜水地帯で起こり,マントルのの化学反応と弧の活動に影響を与える可能性があります.
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