アラスカの氷河で測定された3次元変形
1J. T. Harper and N. F. Humphrey, Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071, USA. W. T. Pfeffer, Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA.
まとめ
氷河の流れは複雑で,ほとんどの動きは床で起こります. 氷の変形速度は深さによって変化したが,滑り速度とは無関係であり,単純なモデルに挑戦した.
科学分野:
- 氷河学 氷河学とは
- 地質物理学 地質物理学とは地質物理学です.
- 地球科学 地球科学 地球科学
背景:
- 温帯渓谷の氷河は,複雑な流れダイナミクスを示しています.
- 氷河の動きを理解することは,海面上昇と水資源の予測に不可欠です.
研究 の 目的:
- ワーチントン氷河の3次元氷の流れを調査するために.
- 氷河運動に対する基礎滑りと内部氷の変形の貢献を決定する.
- 平面張力などの一般的なモデリング仮定の妥当性を評価する.
主な方法:
- 28の掘削孔を使って氷の移動を測定した.
- 氷内の表面運動と張力率の分析.
- 3次元フローフィールドの特徴.
主要な成果:
- 氷河の表面運動の60~70%をベーススライドが占めている.
- 氷の歪み率は上部120メートルでは低く,床に向かって急速に増加した.
- 内部氷の変形は,基礎滑り速度の時間的変化と相関関係を示さなかった.
結論:
- ワーチントン氷河は,基礎滑りが顕著である.
- 平面ストレスは,この氷河の粘着性の流れをモデル化するための不十分な仮定です.
- 詳細な3D測定は,正確な氷河流のモデリングに不可欠です.
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