Array Measurements of Long-period Microtremors in Southwestern Kanto Plain, Japan.
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Accession number;99A0456256
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| Title;Array Measurements of Long-period Microtremors in Southwestern Kanto Plain, Japan. |
| Author;
YAMANAKA HIROAKI
(Tokyo Inst. of Technology, Graduate School)
SATO HIROAKI
(Tokyo Inst. of Technology, Graduate School)
KURITA KATSUMI
(Tokyo Inst. of Technology, Graduate School)
SEO KAZUO
(Tokyo Inst. of Technology, Graduate School)
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Journal Title;Journal of the Seismological Society of Japan. Second Series
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Journal Code:G0931A
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ISSN:0037-1114
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VOL.51;NO.4;PAGE.355-365(1999)
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| Figure&Table&Reference;FIG.12, TBL.2, REF.23 |
| Pub. Country;Japan |
| Language;Japanese |
| Abstract;Array measurements of long-period microtremors were conducted in Kawasaki and Yokohama cities in the Kanto basin to know S-wave velocity profiles for estimating strong ground motion. We observed long-period microtremors at 8 sites by installing temporarily two arrays at each site. Each array consists of 7 vertical seismometers with station spacing of 0.2 to 3km. Phase velocities of microtremors were estimated from an frequency-wavenumber analysis. They show dispersive features in a period range from 0.5 to 5 seconds, suggesting propagation of Rayleigh wave. The phase velocity data were inverted to S-wave velocity profiles of thick sediments by an inversion based on a genetic algorithm. The S-wave velocity profiles are mainly approximated by four layers with S-wave velocities of 0.4-0.6km/s, 1.0km/s, 1.7km/s and 3km/s, respectively. It was found that the S-wave velocity of the 3rd layer is site-dependent. The depths to the interfaces of these layers in the deduced profiles are in agreement with results of seismic refraction and reflection explorations. (author abst.) |
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