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Time-lapse changes of P- and S-wave velocities and shear wave splitting in the first year after the 2011 Tohoku earthquake, Japan: shallow subsurface
https://nied-repo.bosai.go.jp/records/4680
https://nied-repo.bosai.go.jp/records/46801b3ee393-1759-45dc-a8dd-cff9302fed43
| Item type | researchmap(1) | |||||||||||||||||
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| 公開日 | 2023-03-30 | |||||||||||||||||
| タイトル | ||||||||||||||||||
| 言語 | ja | |||||||||||||||||
| タイトル | Time-lapse changes of P- and S-wave velocities and shear wave splitting in the first year after the 2011 Tohoku earthquake, Japan: shallow subsurface | |||||||||||||||||
| タイトル | ||||||||||||||||||
| 言語 | en | |||||||||||||||||
| タイトル | Time-lapse changes of P- and S-wave velocities and shear wave splitting in the first year after the 2011 Tohoku earthquake, Japan: shallow subsurface | |||||||||||||||||
| 言語 | ||||||||||||||||||
| 言語 | eng | |||||||||||||||||
| 著者 |
SAWAZAKI Kaoru
× SAWAZAKI Kaoru
× SAWAZAKI Kaoru
× SNIEDER Roel
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| 抄録 | ||||||||||||||||||
| 内容記述タイプ | Other | |||||||||||||||||
| 内容記述 | We detect time-lapse changes in P- and S-wave velocities (hereafter, V-P and V-S, respectively) and shear wave splitting parameters associated with the 2011 Tohoku earthquake, Japan, at depths between 0 and 504 m. We estimate not only medium parameters but also the 95 per cent confidence interval of the estimated velocity change by applying a new least squares inversion scheme to the deconvolution analysis of KiK-net vertical array records. Up to 6 per cent V-S reduction is observed at more than half of the analysed KiK-net stations in northeastern Japan with over 95 per cent confidence in the first month after the main shock. There is a considerable correlation between the S-wave traveltime delay and the maximum horizontal dynamic strain (MDS) by the main shock motion when the strain exceeds 5 x 10(-4) on the ground surface. This correlation is not clearly observed for MDS at the borehole bottom. On the contrary, V-P and shear wave splitting parameters do not show systematic changes after the Tohoku earthquake. These results indicate that the time-lapse change is concentrated near the ground surface, especially in loosely packed soil layers. We conclude that the behaviour of V-P, V-S and shear wave splitting parameters are explained by the generation of omnidirectional cracks near the ground surface and by the diffusion of water in the porous subsurface. Recovery of V-S should be related to healing of the crack which is proportional to the logarithm of the lapse time after the main shock and/or to decompaction after shaking. | |||||||||||||||||
| 言語 | en | |||||||||||||||||
| 書誌情報 |
ja : Geophysical Journal International en : Geophysical Journal International 巻 193, 号 1, p. 238-251, 発行日 2013 |
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| 言語 | en | |||||||||||||||||
| 出版者 | OXFORD UNIV PRESS | |||||||||||||||||
| ISSN | ||||||||||||||||||
| 収録物識別子タイプ | ISSN | |||||||||||||||||
| 収録物識別子 | 0956-540X | |||||||||||||||||
| DOI | ||||||||||||||||||
| 関連識別子 | 10.1093/gji/ggs080 | |||||||||||||||||
