Research Abstract


Tsunami: Ocean dynamo generator

2014年1月8日 Scientific Reports 4 : 3596 doi: 10.1038/srep03596


杉岡 裕子1, 浜野 洋三1, 馬場 聖至2, 笠谷 貴史1, 多田 訓子1 & 末次 大輔1

  1. 海洋研究開発機構
  2. 東京大学地震研究所
Secondary magnetic fields are induced by the flow of electrically conducting seawater through the Earth's primary magnetic field (‘ocean dynamo effect’), and hence it has long been speculated that tsunami flows should produce measurable magnetic field perturbations, although the signal-to-noise ratio would be small because of the influence of the solar magnetic fields. Here, we report on the detection of deep-seafloor electromagnetic perturbations of 10-micron-order induced by a tsunami, which propagated through a seafloor electromagnetometer array network. The observed data extracted tsunami characteristics, including the direction and velocity of propagation as well as sea-level change, first to verify the induction theory. Presently, offshore observation systems for the early forecasting of tsunami are based on the sea-level measurement by seafloor pressure gauges. In terms of tsunami forecasting accuracy, the integration of vectored electromagnetic measurements into existing scalar observation systems would represent a substantial improvement in the performance of tsunami early-warning systems.