| 研究課題/領域番号 |
21K20374
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| 研究種目 |
研究活動スタート支援
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| 配分区分 | 基金 |
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| 審査区分 |
0204:天文学、地球惑星科学およびその関連分野
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| 研究機関 | 東北大学 |
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研究代表者 |
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| 研究期間 (年度) |
2021-08-30 – 2025-03-31
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| 研究課題ステータス |
交付 (2023年度)
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| 配分額 *注記 |
3,120千円 (直接経費: 2,400千円、間接経費: 720千円)
2022年度: 1,560千円 (直接経費: 1,200千円、間接経費: 360千円)
2021年度: 1,560千円 (直接経費: 1,200千円、間接経費: 360千円)
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| キーワード | Rapid hydration / Reaction zones / Slow Slip Events / 流体フラックス / 岩石流体反応帯 / 地震活動 / 地震モーメント / 地震規模 |
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| 研究開始時の研究の概要 |
地震発生に地殻内の流体が深く関与することが，認識されているが，地殻内で流体がどのように移動するかについては，地熱地帯などの一部の例を除いてはほとんど明らかにされていない．流体流動現象をコントロールする物理パラメータは浸透率である．すなわち，流体-岩石反応帯に保存されている地球化学的証拠を使用して、流体の浸透時間、時間積分された流体フラックスを推定し、それらを地震モーメントとマグニチュードの推定に結び付けることが申請者の手法である.
本研究は，流体の浸透によって引き起こされる地震活動を理解し、そのモデルを提供し，流体駆動による地殻の破砕と地震活動を高い解像度で理解することを目的とする.
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| 研究実績の概要 |
I conducted an analysis of metamorphic rocks that underwent rapid hydration over a period of tens of hours, estimating hydrological properties such as permeability evolution between the host rock and fluid-rock reaction zones. Employing all calculated parameters, I applied the advective reaction-transport equation to model fluid speciation phase equilibrium, estimating fluid volume based on Si solubility. The estimated fluid volumes correspond closely with the results of injection experiments conducted in geothermal fields. Subsequently, these fluid volumes were utilized to approximate seismic moments and magnitudes of potential seismic events.
I identified similarities in both the duration of fluid infiltration and magnitudes to slow slip events and tremors. These significant findings were published in Geophysical Research Letters in 2023, Volume 50, Issue 5, under the title "Short-lived and Voluminous Fluid-Flow in a Single Fracture Related to Seismic Events in the Middle Crust." Additionally, I presented this work as an oral presentation during the Slow-to-Fast workshop held in Taiwan and participated in fieldwork subsequent to the presentation.
During my involvement in several fieldworks in Japan, I collected potential samples for further analysis. Notably, during a visit to the Kochi core samples center, I discovered a core sample from Nobeoka that can be analyzed using the same methodology to potentially uncover evidence of slow slip events.
This research and its subsequent dissemination contribute significantly to our understanding of fluid dynamics and seismic events.
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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
New samples have been selected to employ the same methodology, but for rocks representing different fluid compositions. Estimating timescales using the previous advective-diffusion profile is not feasible, so I am exploring alternative methods. However, estimating timescales and fluid volumes for samples with varying fluid compositions may offer diverse insights into fluid-rock interactions in the continental crust.
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| 今後の研究の推進方策 |
I will be implementing a different method to estimate timescales based on the advective-diffusion profile in titanite. Additionally, I intend to calculate the time-integrated fluid flux for both scapolite-bearing veins and amphibolite epidote-bearing veins. These fluid fluxes can then be utilized to estimate fluid volumes and approximate the magnitudes of potential seismic events triggered by fluids with varying compositions. This approach may shed light on the impact of CO2-bearing fluids on the generation of seismic activity in the continental crust.
Furthermore, I am planning to enhance the visibility of my research by presenting it at the prominent international conference, EGU (European Geosciences Union). Attending this conference will provide an excellent platform to showcase my research findings and engage with the broader scientific community.
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