2005 Fiscal Year Final Research Report Summary
Consideration of seismic tectonics around southern region of Nansei-shoto Islands by Japan-Taiwan Collaborative research-Regional features of subduction zone-
| Project/Area Number |
16540390
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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 |
Solid earth and planetary physics
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| Research Institution | TOKAI UNIVERSITY |
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Principal Investigator |
BABA Hisatoshi TOKAI University, Institute of Oceanic Research and Development, Associate Professor, 海洋研究所, 助教授 (80256180)
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| Co-Investigator(Kenkyū-buntansha) |
IWASHITA Atsushi Kyusyu TOKAI University, School of Engineering, Professor, 工学部, 教授 (40266383)
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| Project Period (FY) |
2004 – 2005
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| Keywords | Taiwan / Underground structure / Hua-Tung Longitudinal Valley / Philippine Sea Plate / Eurasia Plate / Quarry blast Exploration / Artificial Seismic Research / Japan-Taiwan Collaborative Res. |
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| Research Abstract |
In this study, we carried out Seismic Refraction Structural Exploration Survey (SRSES) in the vicinity of Taiwan's Central and Coastal mountain ranges. Since 2004, researchers have completed 25 surveys at 4 quarried locations. These locations have a total of 298 stations established to log data for the SRSES. To aid in inferring details of underground rock formation structure using data logged during pre-excavation blasting, researchers have compiled seven survey profiles (lines A-G) between the two mountain ranges.
The survey uses the Mark Products Company model L-22D seismometer, operating at a sampling rate of 200Hz. A Hakusan Industry Datamark LS8000 digital recorder is used for logging data from both the seismometer as well as signals from a GPS receiver at a precision of 3ms.
The wave form records of line D clearly illustrate the propagation of P-waves and provide observation data up to 30km from the blast epicenter. Observed lines E and F are particularly important due to their locations surrounding the Coastal range. It is suggested that the wave form records on the coastal-side of the mountains be continually monitored for future study.
The travel time plot of line D shows a propagation speed of 4.8km/sec on the surface layer around shock point 3 (SP3), which can also be verified by evidence of exposed outcrops that the surface layer is composed of marble. The subsurface layer exhibits a wave propagation speed of 6.0km/sec. Refraction waves are not observed in the third layer, even at the maximum distance used in this study of 50km from the epicenter.
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