ニューマドリードの地震地帯における時間変動変形
1Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN 47906, USA.
まとめ
新しい地質学的データによると,ニューマドリードの地震地帯は,最近の大規模な地震のためにあまりにもゆっくりと変形している. これは,地質学的な負荷率や断層の性質が数千年にわたって変化し,地震の危険性評価に影響を及ぼすことを意味します.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 地震学 地震学とは
- ジオデシ (Geodesy) とは
背景:
- ニューマドリッド地震帯 (NMSZ) は,米国中部における主要な内板地震リスクである.
- NMSZの変形と地震の可能性を理解することは,危険性評価に不可欠です.
研究 の 目的:
- 地質測定を用いてニューマドリッドの地震地帯における現在の地形変形速度を評価する.
- 観測された変形が過去5000年の大規模な地震の発生を説明できるかどうかを評価する.
主な方法:
- NMSZ全域の新しい地質データ (GPS,InSARなど) の分析.
- 測定されたストレンスレートと,大きな史前地震に必要なストレンスレートの比較.
主要な成果:
- 地質測定では,NMSZの流動変形が非常に遅い,または軽微であることを示しています.
- 観測されたゆっくりとした変形は,過去の大規模地震 (過去5000年) の頻度と大きさを説明できない.
結論:
- NMSZにおける現在の地質学的な負荷率や断層の性質は,数千年の時間スケールで大きく変化する可能性があります.
- この変動性は,安定状態の仮定に基づいた伝統的な地震リスクモデルに挑戦しています.
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