統計的地震学の2つの基本法則のストレスの共通の依存性
Clément Narteau1, Svetlana Byrdina, Peter Shebalin
1Institut de Physique du Globe de Paris (UMR 7154, CNRS, Univ. P7), 4 Place Jussieu, 75252 Paris Cedex 05, France. narteau@ipgp.jussieu.fr
Nature
|December 4, 2009
まとめ
グーテンベルク-リヒター,オモリ-ウツー関係のような統計地震学の力法則は,ストレスの影響を受けます. 余震崩壊率 (c 値) は,主要な衝撃故障スタイルによって変化し,新しいストレスフィールドの洞察を提供します.
科学分野:
- 地震学 地震学とは
- 統計地震学 統計地震学
- 地質物理学 地質物理学とは地質物理学です.
背景:
- グーテンベルク-リヒター関係 (地震の頻度-震度) とオモリ-ウツー法則 (余震崩壊率) は,統計地震学の基本的な力法則である.
- 最近の研究では,グーテンベルク-リヒター b 値が,スタイルとストレスの欠陥と関連付けられています.
- オモリ・ウツー法則のパラメータ,特にc値 (時間遅延) は,ファールティング・スタイルに関連してあまり理解されていません.
研究 の 目的:
- メイン・ショック・フォールティング・スタイルとオモリ・ウツー法のc値との関係を調査する.
- 断層のスタイルが,地震の周波数-大きさの分布に与える影響に類似して,余震崩壊の発生に影響を与えているかどうかを判断する.
- ストレスフィールドを推論するための独立したツールとしてcとbの値の使用を探求する.
主な方法:
- 主な衝撃の断層スタイルに基づいて,余震の配列を分析した.
- パワー・ロー・アフターショックの崩壊の発生時間遅延 (c値) を,異なる断層スタイル (スラスト,ノーマル,ストライクスリップ) で比較した.
- グーテンベルク-リヒター b 値の誤差スタイルへの依存に関する既存の知識と相関する発見.
主要な成果:
- 余震崩壊が始まる前の時間遅延 (c 値) は,正規の故障主ショックと比較して,推力主ショックでは著しく短くなります.
- ストライクスリップメインショックは中間c値を示します.
- c 値と b 値の両方に対するこれらの故障型依存性は,ストレス状態による一般的な統治を示唆しています.
結論:
- グーテンベルク-リヒター関係 (b値) とオモリ-ウツー法則 (c値) の両方が,主ショックの故障スタイルと,その延長により,周囲のストレスフィールドの影響を受けていることが実証されています.
- c と b の値は,地球のストレスフィールドを推論するための独立した,価値のあるプロキシとして機能し,それ以外の場合は直接測定することは困難です.
- この研究は,地震が起こりやすい地域におけるストレス体制を理解するための新しい地震学的ツールを提供します.
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