Japan Geoscience Union Meeting 2015

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International Session (Oral)

Symbol S (Solid Earth Sciences) » S-TT Technology & Techniques

[S-TT13] Recent Advances in Exploration Geophysics (RAEG2015)

Thu. May 28, 2015 2:15 PM - 4:00 PM 102A (1F)

Convener:*Hitoshi Mikada(Kyoto University), Junichi Takekawa(Graduate School of Science, Kyoto University), Junzo Kasahara(University of Shizuoka, Faculty of Earth Scieces), Yoshihisa Iio(Disater Prevention Research Institute, Kyoto University), Yasuo Ogawa(Volcanic Fluid Research Center Tokyo Institute of Technology), Nobukazu Seama(Department of Earth and Planetary Sciences, Graduate School of Science, Kobe University), Tatsuya Sato(Geothermal Energy Research & Development Co., LTD.), Eiichi Asakawa(JGI, Incorporated), Chair:Ehsan Jamali Hondori(JGI, Inc.), Hitoshi Mikada(Kyoto University)

2:15 PM - 2:30 PM

[STT13-14] Development of hydraulic low frequency marine seismic vibrator

*Hiroaki OZASA1, Hitoshi MIKADA2, Fumio SATO1, Fumitoshi MURAKAMI3, Eiichi ASAKAWA3 (1.IHI Corporation, 2.Kyoto University, 3.JGI, Incorporated)

A towed marine seismic vibrator using hydraulic servo system has been developed. We have fabricated a mock-up source with a slightly, say 60-70 %, scaled size to the real design and conducted several evaluation tests in the sea. The vibrator was towed approximately at a depth of 250m in water. The performance such as maximum sound level, frequency characteristic, horizontal directivity, and vertical directivity of the sound field generated from the source mock-up was examined as a field experiment. The sound source level and the frequency characteristic were equal to or higher than the estimated specification between 3Hz and 300Hz. The comparizon of horizontal with the vertical intensity of the generated sound fields indicate that the generated sound field could be regarded nearly omnidirectional. Seismic survey trial using a short streamer was also conducted following the source characteristic examination. A shot gather was acquired by several emission patterns with different frequency bands in the trial. The results showed the performance of the mock-up to be usable as seismic source in shallow water as a vibrator source that uses mechanical oscillation structure.