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タイトル: 底層流による海底地震計周囲の渦の発生の実験的観察
その他のタイトル: Experimental Results of Vortex Generation around Ocean-Bottom Seismograph due to Bottom Current
著者: 笠原, 順三
南雲, 昭三郎
是沢, 定之
大工原, 保
宮田, 秀明
著者(別言語): Kasahara, Junzo
Nagumo, Shozaburo
Koresawa, Sadayuki
Daikuhara, Tamotsu
Miyata, Hideaki
発行日: 1980年8月25日
出版者: 東京大学地震研究所
掲載誌情報: 東京大学地震研究所彙報. 第55冊第1号, 1980.8.25, pp. 169-182
抄録: Oscillational noise has frequently been observed by pop-up ocean bottom seismometers (OBS). The major cause of the noise is supposed to be bottom currents. When the relationship between current speed and shape of the OBS was examined experimentally, Karman vortexes were found to develop about the L-shaped frames, the pressure case of the radio transmitter and the antenna of the transmitter when the current exceeded 20 cm/sec. The Karman vortexes which formed about the antenna were found to be the most undesirable. The frequency of the antenna oscillation was from 3.20 to 3.70 Hz for current speeds of 18 cm/sec and 30 cm/sec, and the amplitude was large enough to saturate the seismometers in the OBS. The frequency was nearly equal to the resonance frequency of the antenna in air and half of the excitation frequency of the Karman vortex. This suggests that the oscillation is the result of resonance in the antenna due to an external force. The use of a fin was effective in reducing the oscillation.
URI: http://hdl.handle.net/2261/12751
ISSN: 00408972


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