2023 Fiscal Year Research-status Report
岩石ー流体反応帯のフラックス解析による地震活動のモデルの構築
| Project/Area Number |
21K20374
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Project Period (FY) |
2021-08-30 – 2025-03-31
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| Keywords | Rapid hydration / Reaction zones / Slow Slip Events |
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| Outline of Annual Research Achievements |
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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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
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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| Strategy for Future Research Activity |
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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| Causes of Carryover |
I am planning to finish current analysis and publish a paper based on the results. I will also present at international conference with my research progress.
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