パークフィールドのサンアンドレアス断層に沿った地震後の緩和は,連続した地震観測から得られた
F Brenguier1, M Campillo, C Hadziioannou
1Sismologie, Institut de Physique du Globe de Paris (IPGP) and CNRS, 4 Place Jussieu, 15252 Paris, France. fbrengui@ipgp.jussieu.fr
まとめ
大規模な地震はサンアンドレアス断層地帯に沿った地殻の性質を変化させ,地震速度の変化と非火山性震動を引き起こします. これらの影響は長年にわたって持続し,長期にわたる断層地帯の乱れを示しています.
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
- テクトニクス (地質学) とは
背景:
- 大規模な地震は,断層地帯の物理的性質を大幅に変化させることができます.
- これらの乱れを理解することは,地震の危険性評価に不可欠です.
研究 の 目的:
- サンアンドレアス断層地帯の地殻特性に対する大規模な地震の長期的な影響を調査する.
- 地震速度の変化と非火山の震動活動を相関させるため.
主な方法:
- 周囲の地震騒音の相関を用いた地震速度の変化の分析.
- 非火山の震動活動を監視する.
- グローバル・ポジショニング・システム (GPS) による滑り後のデータとの比較.
主要な成果:
- 2003年のサンシメオン地震と2004年のパークフィールド地震は,地震の速度を低下させた.
- 地震後のサンアンドレアス断層に沿って,非火山的震動活動の増加が観察されました.
- パークフィールド地震後の3年以上,速度減少と震動活動は上昇し続け,時間とともに衰退しました.
結論:
- 地震速度の変化は,浅いコセイミックダメージと深いストレス変化/リラクゼーションに関連しています.
- 非火山の震動活動は,断層地帯における地震後のプロセスの敏感な指標である.
- 地震はサンアンドレアス断層地帯の機械的性質に永続的な変化をもたらします.
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