ペルー中央部のメガトラストで地震と無地震が滑り落ちている
Hugo Perfettini1, Jean-Philippe Avouac, Hernando Tavera
1Institut de Recherche pour le Développement, 44 Boulevard de Dunkerque, 13572 Marseille cedex 02, France. hugo.perfettini@ird.fr
Nature
|May 7, 2010
まとめ
サブドクションメガストラストの地震および無地震の滑り方は,プレート運動に対応します. ペルー中部では,アセイミック・スリップがスリップの70%を占め,地震の頻度と震度に影響を与えます.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- テクトニクス (地質学) とは
- 地震学 地震学とは
背景:
- サブドクションメガトラストは,地震性 (地震) と非地震性 (クリープ) スリップモードの両方を表しています.
- これらのスライドモードは,長期のプレート構造の動きに対応するために相互作用します.
- 浅いメガスラストゾーンは異質なストレスを示し,両滑りタイプの共存を示しています.
研究 の 目的:
- ペルー中央部のメガトラストにおける地震と無地震の滑り合いの相互作用を調査する.
- 大規模な地震の発生と特徴にアセイミック・クリープがどのように影響するかを理解する.
- ナスカ山脈のような地質学的特徴が滑り方を調節する役割を分析する.
主な方法:
- ピスコ地震 (Mw = 8.0) の破裂過程の分析.
- 地震間および地震後の変形のモデリング.
- アスペリティとアセイミック・アフタースリップ・パッチの識別.
主要な成果:
- ピスコ地震は,ロックされたアスペリティを破裂させ,隣接するパッチにアセイミック・アフタースリップを引き起こしました.
- 納スカ山脈の沈殿した領域は,低レベルの地震間結合を示し,破裂障壁として機能した.
- アセイミック・スリップに関連した速度強化パッチは,地震の規模と頻度を制御します.
結論:
- ペルーの中央のメガトラストは,交互に減速 (地震) と増速 (非地震) のパッチで構成されています.
- アシズミック・スリップは,スリップ予算の総額のうち,相当な割合 (50~70%) を占めています.
- ピスコ地域でのMw = 8.0の地震の推定戻り期間は約250年です.
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