大陸のストライクスリップ断層の下のマントルの流れ: 1999年のヘクター鉱山地震後の地震後の変形
F F Pollitz1, C Wicks, W Thatcher
1U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, CA 94025, USA.
まとめ
カリフォルニア州で大規模な地震が発生.
科学分野:
- * 地質物理学と地質学
- * 地震学と地測量学
背景:
- * カリフォルニアのモハベ砂漠で起きた1992年のランダーズ (Mw 7.3) と1999年のヘクター鉱山 (Mw 7.1) の地震は,地殻に大きな変形を引き起こした.
- * 地震後の地質調査データは,水平速度の衰退と象限上昇を含む予期せぬパターンを明らかにした.
研究 の 目的:
- * 大規模な地震後の地殻の加速変形の原因を調査する.
- * 地震サイクルにおける上層マントルダイナミクスの役割を理解する.
主な方法:
- *ヘクター鉱山地震後に収集された地質データ (GPS測定など) の分析.
- * マントルフローモデルの文脈における変形パターンの解釈.
主要な成果:
- *観測された地震後の変形は,地震によるストレス変化に反応する上層マントルの活発な流れに起因する.
- * 下層はストレスガイドとして作用し,上層の地殻の過程と上層マントルの動態を結びつける.
結論:
- *マントルの一時的な流れは,地震サイクルにおける重要な要因である.
- * 下層は,上層とマントルの間のストレスを伝達する上で重要な役割を果たします.
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