A study of long-period ocean-bottom motions in the Nankai trough, southwestern Japan

2015 Fiscal Year Final Research Report

• Project/Area Number: 26750132
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Natural disaster / Disaster prevention science
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: Nakamura Takeshi 国立研究開発法人海洋研究開発機構, 地震津波海域観測研究開発センター, 技術研究員 (40435847)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 海底長周期地震動 / 海底強震動 / 強震観測 / 海底観測 / 波動伝播 / 差分法 / 南海トラフ / 堆積層

Outline of Final Research Achievements

Long-period ground motions have often been observed in plain and basin areas on land at moderate to large earthquakes. However, the generation and development of such motions in ocean areas have only been suggested indirectly by simulation results reproducing land station data. In this study, we showed observational evidence for "long-period ocean-bottom motions" from strong-motion data in deep seafloor areas around the Nankai trough, southwestern Japan. We also reproduced characteristics of observed long-period ocean-bottom motions with computer simulations of seismic wave propagation. Our simulation results demonstrated that low-velocity oceanic sediment layers around the trough areas significantly contribute to the development of the motions.

Free Research Field

地震学