[S-CG44] Science of slow-to-fast earthquakes

[SCG44-33] Geological structure and mechanical properties due to the collision of multiple seamounts in a accretionary wedge: insights from numerical simulations

*宮川 歩夢¹、野田 篤¹、高下 裕章¹ (1.国立研究開発法人　産業技術総合研究所 地質情報研究部門)

キーワード：前弧付加体、海山衝突、沈み込み帯、数値シミュレーション

We propose a conceptual geological model for the collision of multiple basement topographic highs (e.g., seamounts, ridges, and horsts) with a forearc accretionary wedge. We conducted numerical simulations using the discrete element method to examine the effects of three seamount collisions with forearcs. Multiple seamount collisions create a cycle of formation of seamount collisional structures. At a low horizontal compressive stress, a “shadow zone” is formed behind (i.e., seaward of) the seamount. When the next seamount collides, the horizontal compressive stress increases and tectonic compaction progresses, which reduce the porosity in the underthrust sediments. The strong horizontal compressive stresses associated with the current seamount collision has increased the pore pressure within the underthrust sediments associated with previous seamounts.