| 研究課題/領域番号 |
23K22843
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| 補助金の研究課題番号 |
22H01573 (2022-2023)
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| 研究種目 |
基盤研究(B)
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| 配分区分 | 基金 (2024)
補助金 (2022-2023) |
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| 応募区分 | 一般 |
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| 審査区分 |
小区分22020:構造工学および地震工学関連
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| 研究機関 | 東京大学 |
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研究代表者 |
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| 研究分担者 |
加藤 愛太郎 東京大学, 地震研究所, 教授 (20359201)
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| 研究期間 (年度) |
2022-04-01 – 2026-03-31
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| 研究課題ステータス |
交付 (2024年度)
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| 配分額 *注記 |
15,860千円 (直接経費: 12,200千円、間接経費: 3,660千円)
2025年度: 3,770千円 (直接経費: 2,900千円、間接経費: 870千円)
2024年度: 5,980千円 (直接経費: 4,600千円、間接経費: 1,380千円)
2023年度: 3,380千円 (直接経費: 2,600千円、間接経費: 780千円)
2022年度: 2,730千円 (直接経費: 2,100千円、間接経費: 630千円)
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| キーワード | Fault rupture / complex geometry / consistent stress / super-shear rupture / effect of geometry / high fidelity models / fault rupture / large sclae simulations / super-shear / PDS-FEM / far-field boundary / off-fault damage zone / visco-plasticity / rupture speed / sub-Rayleigh / far-field loading / MTL / HPC |
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| 研究開始時の研究の概要 |
Though earthquake generating faults have geometrically complex structure, existing simulations use simple geometric models. Further, the initial stress of standard models is incompatible with fault geometry and material distribution. Both this geometric simplification and incompatible initial stress can make the standard models diverge from the response of the natural faults. We plan to compare geometrically complex model with consistent stress and standard model to quantify the difference in their responses to demonstrate the importance of geometric complexities.
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| 研究実績の概要 |
As planned, we performed large scale simulations of the rupture of the Palu-Koro fault under the initial conditions corresponding to the 2018 event and reproduced the corresponding super-shear rupture. We showed that the initial stress and frictional properties have a significant influence on the nature of the rupture, such as when a rupture jumps to neighboring faults, by simulating several 2D multiple fault systems. We developed two geometric models of the median tectonic line. The first model is based on the data provided by J-SHIS. Although this is the standard model, it is highly simplified. Therefore, we generated an accurate geometric model based on fault trace data from the Geological Survey of Japan (GSJ), and preliminary simulations were performed on coarse mesh models.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
We successfully completed all the tasks planned for FY2023 except SCEC benchmark verification. The reason for this exception is the difficulty of reproducing the artificial initial stresses of the SCEC benchmarks using far-field boundary conditions. To prevent this from hampering our progress, we verified our simulations by reproducing some theoretically expected behavior. We have automated the tedious and time-consuming task of geometric modelling and mesh refinement using fault trace data as input. This allows us to easily correct our models or generate models for other faults. We have submitted two papers to AGU Journal of Geophysical Research and Computational Mechanics by Springer. Successful completion of all planned tasks led us to conclude that the research has progressed well.
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| 今後の研究の推進方策 |
We plan to identify the far-field boundary conditions required to trigger different rupture patterns on a coarse mesh, and simulate fine mesh models of both the simplified fault geometry from J-SHIS data and the detailed geometry from GSJ data. These two simulations will be compared to highlight the importance of using detailed fault models and setting the initial stress consistent with the complex fault geometry and distribution of nonlinear materials. Further, we plan to study the rupture characteristics under heterogeneous distribution of friction parameters. We plan to make another attempt at verification using SCEC benchmark tests to build confidence. Code performance on ARM A64FX based Wisteria supercomputer will be improved since the Oakbridge system has been decommissioned.
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