2023 Fiscal Year Research-status Report
Advancements to predict local earthquake ground motions with applications in the Kansai region
| Project/Area Number |
23KF0149
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| Research Institution | Kyoto University |
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Principal Investigator |
浅野 公之 京都大学, 防災研究所, 准教授 (80452324)
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| Co-Investigator(Kenkyū-buntansha) |
HALLO MIROSLAV 京都大学, 防災研究所, 外国人特別研究員
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| Project Period (FY) |
2023-09-27 – 2026-03-31
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| Keywords | earthquakes / strong ground motion / site effects / amplification / spectral ratio / Kansai |
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| Outline of Annual Research Achievements |
In accordance with the Research Plan, we reviewed earthquake data and seismic velocity models available for the inner Kansai area (Osaka, Kyoto, and Nara basins). To investigate the empirical site response, we evaluated Horizontal-to-Vertical spectral ratios from 107,679 earthquake waveforms recorded in the years 1994-2023 at 449 monitoring sites (national, prefectural, and institutional monitoring networks). The processing was performed by our newly programmed software package that is custom-made for Japanese strong-motion waveform data. We found that the Fourier frequency and directionality of spectral peaks correlate with the thickness and disposition of the sedimentary lithological layer, respectively. These results were recently presented at the Annual Meeting of the Disaster Prevention Research Institute. Next, the physics-based site response modeling method is tackled in our newly published peer-reviewed publication. This method uses near-surface velocity profiles to predict the local amplification of seismic waves and it will be further developed in the next phase of this project. In addition, beyond the initial plan, we started with an analysis of the empirical site response at the strong-shaking zone of the M7.6 Noto earthquake, which occurred on January 1, 2024. This analysis is of interest because it is closely related to the project topic and up to date.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
Overall, the progress of this research project is smooth and without delays. In this phase, we investigated the empirical site response more deeply than originally planned, because of the occurrence of unexpected phenomena such as the directionality of spectral peaks. Still, it is in accord with the initial research plan. In the next project phases, we will focus on the spectral inversion of empirical amplification and further developments in the theoretical method. Beyond the initial plan, we started with an analysis of the newly emerged 2024 M7.6 Noto earthquake in order to study the site-specific response during strong ground shaking. This topic is important for the seismic hazard at long return periods, which are used for buildings of special importance (included in the initial research plan). We were able to perform the analysis very quickly because we utilized our new software package developed for the analysis of Japanese strong-motion data.
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| Strategy for Future Research Activity |
In the next phase of the project, we will finalize the analysis and proceed to publication about the site response during the 2024 M7.6 Noto earthquake. Then, following the initial Research Plan, we will evaluate the empirical amplification at selected sites in the Kansai area by using the spectral inversion method. The empirical amplification will be compared with a prediction by the theoretical physics-based method. Keeping in mind features investigated in the previous phase, we will perform developments in the physics-based method, and conduct sensitivity tests. Next, we will use the available Osaka-Kyoto-Nara basin velocity model and apply the method to produce regional 2D amplification maps. We will be able to submit a peer-reviewed paper in this project phase. Also, we plan to present our results at two national and one international scientific conference in FY 2024. There are no significant changes in the research plan, yet it is extended by the analysis of the 2024 Noto earthquake.
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| Causes of Carryover |
購入予定の備品及び消耗品の納入価格が当初の想定よりも安価となったため、次年度使用額が生じた。これらは、今年度に得られた成果を次年度開催される学会にて発表するための旅費に充当する。
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