2018 Fiscal Year Research-status Report
Numerical simulations for the formation of dynamic decollement and subduction plate interface
| Project/Area Number |
18K13643
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
Bauville Arthur 国立研究開発法人海洋研究開発機構, 数理科学・先端技術研究分野, 研究員 (90811498)
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Keywords | accretionary prism / critical taper theory / fault weakening / numerical simulations / structural style |
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| Outline of Annual Research Achievements |
I successfully carried out the first part of my project. The initial problematic was modified to address the following problem.
In natural active margins underthrusting is observed when the plate boundary (i.e. basal fault) is weak compared to the wedge strength. However, a static force balance of this system indicates the opposite behavior.
To resolve this paradox, I carried out a mathematical analysis and numerical simulations to study the control of fault weakening on the structural styles of underthrusting-dominated accretionary wedges. The numerical results are bounded by the analytical solutions and reveals transient behaviors.
This study reveals that the weakaening of an initially strong fault favors underthrusting rather than frontal accretion, in agreement with natural observations.
The results of this study have been summarized in a manuscript that will be submitted in May 2019.
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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
As initally planned, the first study was carried out during the first year of the project. The manuscript will be submitted this month (May, 2019). Furthermore, numerical results show an unexpected behavior which has strong implications for the development of overpressure/underpressure in accretionary wedges and orogens. Initial tests have already been performed and data treatment have already been performed.
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| Strategy for Future Research Activity |
The initial plan of my project was to carry lithospheric scale numerical simulations in the next fiscal year. However, the results of the simulations performed during the first study are very rich. Indeed, simulations reveal transient changes of the stress field associated with faulting events. The magnitude of pressure change during these transient events could explain the sudden pressure drop observed in metamorphic rocks at peak pressure. This is a much debated topic in geology at the moment and the effect I observed has not been discussed yet and has a lot of potential. Therefore, in the next fiscal year I want to focus on analyzing data and writing a manuscript about these new results.
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| Causes of Carryover |
Funds for a computer were not used because institute budget got available for this purpose. The planned publication budget for the first will be used in the next year because the mansucript has not been published yet.
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