Japan Geoscience Union Meeting 2022

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[E] Oral

S (Solid Earth Sciences ) » S-CG Complex & General

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

Fri. May 27, 2022 3:30 PM - 5:00 PM 103 (International Conference Hall, Makuhari Messe)

convener:Aitaro Kato(Earthquake Research Institute, the University of Tokyo), convener:Yoshiyuki Tanaka(Earth and Planetary Science, The University of Tokyo), Asuka Yamaguchi(Atomosphere and Ocean Research Institute, The University of Tokyo), convener:Takahiro Hatano(Department of Earth and Space Science, Osaka University), Chairperson:Asuka Yamaguchi(Atomosphere and Ocean Research Institute, The University of Tokyo), Yoshitaka Hashimoto(Kochi University)

4:15 PM - 4:30 PM

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

*Ayumu Miyakawa1, Atsushi Noda1, Hiroaki Koge1 (1.Institute of Geology and Geoinformation , Geological Survey of Japan, AIST)

Keywords:Forearc accretionary wedge, Seamount Collision, Subduction zone, Numerical simulation

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.