日本地球惑星科学連合2018年大会

講演情報

[JJ] ポスター発表

セッション記号 M (領域外・複数領域) » M-GI 地球科学一般・情報地球科学

[M-GI28] 計算科学による惑星形成・進化・環境変動研究の新展開

2018年5月23日(水) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:林 祥介(神戸大学・大学院理学研究科 惑星学専攻/惑星科学研究センター(CPS))、小河 正基(東京大学大学院総合文化研究科広域科学専攻)、井田 茂(東京工業大学地球生命研究所、共同)、草野 完也(名古屋大学宇宙地球環境研究所)

[MGI28-P03] 粘性率の応力履歴依存を考慮した、プレート運動を伴う3次元マントル対流モデルの開発

*宮腰 剛広1亀山 真典2小河 正基3 (1.海洋研究開発機構、2.愛媛大学、3.東京大学)

キーワード:マントル対流、数値シミュレーション、プレート運動、応力履歴依存粘性

In today’s Earth, solid plate interiors and ruptured plate boundaries coexist at a stress level typical for the Earth’s interior. A stress much higher than this level is necessary to rupture an intact plate and to introduce a new plate boundary. Once a plate boundary develops, however, it does not immediately disappear, even if the stress is reduced to the original level: the rheological state of a plate depends on its stress history. We reproduced tectonic plates in our three-dimensional mantle convection models calculated with ACuTEMAN code (Kameyama 2005; Kameyama et al. 2005) by introducing this stress-history dependent rheology. We discriminated the plate boundaries and plate interiors by introducing a damage parameter that depends on the stress-history that the material has experienced: this parameter takes a value less than one in intact plate interiors, but takes a large value at plate boundaries. One of the difficulties we encountered in calculating this model is the numerical instability that occurs when a fine structure with a large viscosity contrast develops along plate boundaries: The viscosity contrast becomes as large as three orders of magnitude. To avoid this difficulty, we introduced a diffusion of the damage parameter. The magnitude of the diffusion is adjusted so that it does not affect the global configuration of tectonic plates but does smear out the fine structures at plate boundaries. In the poster, we will present some examples of tectonic plates that we calculated.