ヒマラヤのフロント・スラストの地震再発と断裂の動態,インド
S Kumar1, S G Wesnousky, T K Rockwell
1Center for Neotectonic Studies, University of Nevada, Reno, NV 89557, USA. senthil@seismo.unr.edu
まとめ
インドのブラックマンゴ断層は,過去650年間に大規模な地震があった証拠を示しています. この断層系は,活発なヒマラヤのフロント・スラスト地域における重要な上昇と地殻の縮小に貢献しています.
科学分野:
- 地質学 地質学 地質学
- 地震学 地震学とは
- テクトニクス (地質学) とは
背景:
- ブラックマンゴ断層はインド北西部の重要な構造的特徴であり,活動的なヒマラヤ前頭推力 (HFT) のセグメント間の動きに対応しています.
- 地震の歴史と変形を理解することは,この地域の地震リスクの評価に不可欠です.
研究 の 目的:
- ブラックマンゴ断層に関連した古地震の歴史と変形速度を調査する.
- ヒマラヤのフロント・スラスト (HFT) 全体の滑り率と地殻の縮小を定量化するために.
主な方法:
- 表面破裂事件の古地震学的な分析.
- マルカンダ川の地質測定とテラス上昇分析.
- 構造地質学 断層幾何学の解釈.
主要な成果:
- ブラック・マンゴ断層では,紀元1294年と紀元1423年以降,少なくとも2つの大きな地表破裂地震が起き,その震度がそれぞれ4.6mと2.4-4.0mであった.
- ホロセンの半ば以来,基礎のHFTの上昇率は4.8 ± 0.9 mm/年であり,重要な地震活動を示しています.
- フォールト・スライドと地殻の縮小率は,それぞれ約9.6mm/年,8.4mm/年で,HFTの30°の沈下を想定します.
結論:
- ブラックマンゴ断層は,大規模な地震を生成できる活発な構造です.
- HFTは,インド北西部の実質的な構造的縮小と上昇に対応しており,ブラックマンゴ断層のような断層からの大きな貢献があります.
- この構造的に活発なゾーンにおける地震の危険性を理解するために,継続的なモニタリングと研究は不可欠です.
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