2006 Fiscal Year Final Research Report Summary
Estimation of three dimensional subsurface structure in Fukui Plain based on high-density observation of various kinds of ground vibration
| Project/Area Number |
16560409
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural engineering/Earthquake engineering/Maintenance management engineering
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| Research Institution | University of Fukui |
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Principal Investigator |
KOJIMA Keisuke University of Fukui, Faculty of Engineering, Associate Professor, 工学部, 助教授 (40205381)
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| Co-Investigator(Kenkyū-buntansha) |
NOGUCHI Tasuya Tottori University, Faculty of Engineering, Research Associate, 工学部, 助手 (20379655)
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| Project Period (FY) |
2004 – 2006
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| Keywords | S-wave velocity / Damping / Quaternary structure / Microtremor / Array observation / Strong motion / Inversion Analysis / Gravity anomaly |
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| Research Abstract |
The accurate evaluations of Quaternary structure of the region are indispensable in order to accurately predict the seismic damage. However, deep borehole, PS logging and elastic wave exploration have been executed only on limited points around the Fukui Plain. The problems treated in this study are statistical estimations of the 3D Quaternary configuration of the Fukui Plain based on various high-density ground vibration records. Firstly, microtremor array observations have been conducted at almost one hundred sites. The observed phase velocitie at each site were inverted to vertical S-wave profiles using a genetic algorithm. To interpolate the array observations, the 3-components single-site microtremor observations were carried out in every mesh of the 1 minute interval which covers the Fukui Plain. Next, we proposed an inversion procedure to estimate source, attenuation and site effect from observed seismic spectra. We back-analyze those three unknown effects, adopting the omega-squared source model, frequency dependent Qs-value, and multi refection of SH-wave in horizontal layering sediments. Applying this inversion procedure to the actual earthquake records observed at the stations deploying in and around Fukui plain, we evaluate the 2-D subsurface structure beneath the plain up to the tertiary. It was confirmed that the identified S-wave velosity structure give a fairly good agreement between observed and calculated spectra, the evaluated structure is harmonized with the existing exploration data. Finally, the 3D configuration models of Quaternary of the Fukui Plain have been evaluated by using kriging and cokriging procedure in which the correlations of the estimated depths of quaternary with the altitudes of the sites were taken into account. By comparing with kinds of inversion analysis results and boring data, the validity of the estimated structure was confirmed.
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Research Products
(16 results)
