日本地球惑星科学連合2015年大会

講演情報

インターナショナルセッション(ポスター発表)

セッション記号 S (固体地球科学) » S-SS 地震学

[S-SS02] Frontier studies on subduction zone megathrust earthquakes and tsunamis

2015年5月25日(月) 18:15 〜 19:30 コンベンションホール (2F)

コンビーナ:*金川 久一(千葉大学大学院理学研究科)、Demian Saffer(Dept. of Geosciences, The Pennsylvania State University, USA)、Michael Strasser(Geological Institute, Seiss Federal Insitute of Technology ETH Zurich)、山田 泰広(京都大学工学研究科都市社会工学専攻)、小平 秀一(海洋研究開発機構 地球内部ダイナミクス領域)、日野 亮太(東北大学災害科学国際研究所)、氏家 恒太郎(筑波大学生命環境系)、伊藤 喜宏(京都大学防災研究所)

18:15 〜 19:30

[SSS02-P01] 動力学的断層破壊シミュレーションによる巨大地震の断層浅部の挙動の検討

*津田 健一1石井 透2小川 幸雄1渡辺 孝英1浦谷 裕明3岩瀬 聡3アンプエロ ジャンポール4 (1.大崎総合研究所、2.清水建設技術研究所、3.中部電力株式会社、4.カリフォルニア工科大地震学教室)

Recent inter-plate mega-thrust earthquakes, such as the 2011 Off the Pacific Coast of Tohoku earthquake (Tohoku Earthquake, Mw 9.0), the 2010 Maule, Chile earthquake (Mw 8.8) and the 2004 Sumatra earthquake (Mw 9.2), revealed some special features of ruptures, such as very large slip (order of several ten meters) and limited short period seismic radiations close to the trench. However, the mechanical origin of these phenomena has not been clarified yet.
In this study, we carry out simulations of the rupture process of large mega-thrust earthquakes based on dynamic models to understand the behavior of shallow parts of the faults. The model is governed by a slip-dependent friction law (Ida, 1972). The simulations employ the 3D Spectral Element Method (Galvez et al., 2014), which is numerically stable and accurate even for subduction models with low dipping angle. Based on these simulations, we explored some possible hypothesis for the generation of large slip on the shallow parts of the faults: large stress drop and thermal pressurization (e.g., Bletery et al., 2014). The results of our dynamic simulations provide useful clues to understand more generally the behavior of shallow parts of the mega-thrust earthquake faults.