カラコーラム断層の滑り率の測定は,断層運動の世俗的な変動を暗示する可能性がある
M-L Chevalier1, F J Ryerson, P Tapponnier
1Laboratoire de Tectonique, Mécanique de la Lithosphère, Unité Mixte de Recherche (UMR) 7578, CNRS, Institut de Physique du Globe de Paris, 75252 Paris Cedex 05, France.
Science (New York, N.Y.)
|January 22, 2005
まとめ
ベリリウム10による年代測定は,カラコラム断層の長期滑り率10.7mm/yrを明らかにし,最近の測定値より大幅に高い. これは,地質学的時間尺度における大幅な滑り率の変動を示唆している.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 四次地質学 四次地質学
- テクトニクス (地質学) とは
背景:
- カラコーラム断層は,中央アジアにおける主要な地形構造の特徴である.
- 最近の地質測定 (InSAR) により,断層の滑り率が低いことが示唆されています.
- 長期の滑り率を理解することは,地震リスクの評価に不可欠です.
研究 の 目的:
- コスモゲンヌクレイド年代測定を用いてカラコラム断層の長期滑り率を決定する.
- 長期の滑り率を最近の地質測定値と比較するために.
- 断層滑落の時間的変動性を調査するために.
主な方法:
- ベリリウム-10 (10Be) を使用した表面曝露年代測定.
- ガー流域の西にあるカラコーラム断層の一部におけるオフセットモレーンの分析.
- インターフェロメトリック合成開口レーダー (InSAR) データとの比較.
主要な成果:
- 140万年前から2万年前までの期間に,右側滑り率10.7 ± 0.7 mm/yrの長期右側滑り率が決定されました.
- この長期的な割合は,最近のInSARデータ (≈ 1 ± 3 mm/yr) から推測された滑り率の約10倍です.
- この不一致は,断層滑りにおける重大な変動を,百年から千年までの時間スケールで示している.
結論:
- 地質学的データから得られた長期の滑り率は,短期的な地質測定から実質的に異なる可能性があります.
- カラコーラム断層は,高低活動期間のエピソード的な滑り方を経験している可能性が高い.
- 異なる断層ゾーン (地震発生性,脆性,柔軟性) の間の機械的結合は,これらの滑り率の変動を誘導する可能性があります.
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