Proj
J-GLOBAL ID:200904036079791370  Research Project code:0450021945 Update date:Nov. 08, 2004

12 hours of fluctuation of sonic speed in the sea through activation of inner tidal wave

内部潮汐波の励起による海中音波速度の12時間変動
Study period:2003 - 2004
Research overview:
The ultimate goal of this study is to clarify the mechanism of 12 hours of fluctuation of sonic speed in the sea found in measuring earthquake in the bottom of sea. Here, a hypothesis that activation of inner tidal wave would generate 12 hours of fluctuation is set. It means the mechanism that 12 hours period of fluctuation was generated through change of structural density in transmission route of sonic speed in the sea activated by inner tidal wave and requires examining its validity. For that purpose, this study set two issues. One is to develop an instrument to measure actual fluctuations caused by inner tidal wave estimated by numerical calculation. Based on the results of numerical calculation, it has been clear that in case of being activated by the inner tidal wave, a centimeter order of superficial fluctuations in the sea is caused and it is possible to sense them as pressed fluctuations in the bottom of sea. Through observing pressed fluctuations in the bottom of sea for a long time, an observation system having preciseness and resolution that can record the amplitude and phase of activated inner tidal wave is to be developed. The other is to integrate along the sonic route in the sea amounts of changes in structural density in the low rate phase generated by activation of inner tidal wave and to debate whether the time difference generated through them is valid with the arrival time difference detected by observation.
Project Organization (1):
  • (C013000000)
Research program: Grant-in-Aid for Scientific Research
Ministry with control over the research :
Ministry of Education, Culture, Sports, Science and Technology

Return to Previous Page