1988 Fiscal Year Final Research Report Summary
Characteristics of Earthquake Motious in the Boundary Zone between the Plain and the Mountains
| Project/Area Number |
62550420
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Building structures/materials
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| Research Institution | Osaka Institute of Technology |
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Principal Investigator |
OHBA Shintaro Osaka Institute of Technology, 工学部, 助教授 (50079521)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Earthquake observation / Mountain / Plain / Boundary zone / Acceleration / Predominant period / duration time / 表面波 |
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| Research Abstract |
The Osaka Plain is surrounded by mountainous regions and is located in the northeast of a submerged oval-shaped basin with a 40 Km mior axis and 80 Km major axis. Earthquake motions in the Osaka Plain, surrounded by mountains on all sides, are affected not only by ground conditions but also largely by the topography around the observation station, which demonstrates the following intersting characteristics.
(1) Earthquake duration in the central part of the plain is remarkably longer than in the surrounding mountains. This is due to the fact that the main motion is compounded by surface waves propagated from the surrounding mountains.
(2) Predominant periods in the plain can be classified into three band: a 0.2 to 0.6 second band, an approx, 1 second band and a 1.5 to 4 seconds band. The short period band of the 0.2 to 0.6 second band is affected by local ground conditions of the surface layer of the observation station. The period band of approx. 1 second is due to the surface wave propagated through sedimentary layer of the plain.
(3) The maximum acceleration is caused by the main wave whose short period component of less than 1 second is predominant. The acceleration in the plain is usually larger than that in surrounding mountains. The acceleration amplitude in the boundary between the plain and the mountains is especially large. Amplification of an acceleration amplitude in the plain is remarkable in the long period zone of more than 1 second when compared with that in the mountain regions.
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Research Products
(10 results)
