2004 Fiscal Year Final Research Report Summary
A study on ground-motion amplification and wave-propagation characteristics in a sedimentary basin
| Project/Area Number |
15560411
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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 | Meisei University |
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Principal Investigator |
TOSHINAWA Takumi Meisei University, Department of Architecture, 理工学部, 教授 (00188749)
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| Project Period (FY) |
2003 – 2004
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| Keywords | Strong-motion Observation / Microtremor Measurements / Sedimentary Layers / Ground-motion Amplification / Natural Period / Underground Structure |
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| Research Abstract |
Strong-motion observation and microtremor measurements were carried out in order to investigate ground-motion and wave-propagation characteristics. The research field concerned herein is Kofu basin which is located in the western part of the Tokyo Metropolitan area. As of April 2004,over 150 events including 2004 Niigataken-chuetsu, 2003 Miyagiken-oki earthquakes have been observed by strong-motion stations deployed in the field. The strong-motion observations indicate that larger amplification and longer duration of strong motions were observed on sedimentary basin in comparison to on mountains and hills. The observation also indicates that amplification and duration of strong motion depends on the magnitude of earthquakes because larger earthquakes contain long-period components while smaller earthquakes contain short-period components. Microtremor observations for long-period components were carried out in 2003 and 2004,with the number of total observation points is about 260. They indicate that natural period of the deep sedimentary layer ranges about 1 to 8 sec and is shorter in the northern part of the basin and the period becomes longer as it goes southward. On the alluvial fen area which consists of thick gravel, marked natural period cannot be found. This is probably because there is less high velocity contrast between the surface layer and basement on such area. From the distribution of natural period and the quarter-wavelength law, the thickness of the deep sedimentary layer is estimated, to be from 0.5 to 2km.
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Research Products
(6 results)
