上板の硬さは,巨大地震の深度変動の破裂行動を決定する
Valentí Sallarès1, César R Ranero2,3
1Barcelona Center for Subsurface Imaging, Institute of Marine Sciences, CSIC, Barcelona, Spain. vsallares@icm.csic.es.
Nature
|November 29, 2019
まとめ
浅いメガトラストの地震は 深い地震と比較して 明確な破裂行動を示します この研究では 岩石の硬さの違いが 障害のメカニズムではなく これらの違いを説明し 津波の警告に 役立つ可能性があることが明らかになりました
科学分野:
- 地理学
- 地震学
- 地震科学
背景:
- サブダクションゾーンにおけるメガスラスト地震は,深度依存の破裂特性を示します.
- 浅い破裂はより大きな滑り,より長い期間,そしてより深い出来事よりも異なるエネルギー放射を持っています.
- これらの性質は 限られた警告で破壊的な津波を引き起こします
研究 の 目的:
- 観測された深度依存の地震破裂の基本的な物理的原因を特定する.
- 地震源の性質と焦点の深さを結びつける量的な枠組みを開発する.
- 地震の滑り方,大きさ,津波の可能性を予測する.
主な方法:
- グローバル・サブデュークション・ゾーンの圧縮波速度モデルの分析.
- 地震の焦点深さの正確な推定と現実的な弾性特性の統合.
- オーバーライディング上のプレートにおけるダイナミック・ストレスの移転のモデリング.
主要な成果:
- 上の板の硬さの系統的な深さの変動が一般的な原因とされています.
- この硬度変動は,故障メカニズムの変化を誘発することなく,対照的な破裂行動を説明します.
- このモデルは共地震と地震の大きさを 予測しています
結論:
- メガスラストの地震の破裂の振る舞いを支配するプレートの深度依存の剛性変動.
- この発見は観測された地震現象に 統一された物理的な説明を提供する.
- この結果は,地震の大きさの推定と津波の早期警告システムを強化する可能性を秘めています.
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