Points to lines/surface: Development of innovative analytical methods for next-generation seismic/tsunami data

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03693
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17040:Solid earth sciences-related
• Research Institution: Hokkaido University
• Principal Investigator: Yomogida Kiyoshi 北海道大学, 理学研究院, 名誉教授 (70230844)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 次世代高密度地震津波観測網 / DAS / 海底光ケーブル / 海底水圧計 / 表面波 / 浅部S波構造 / 津波励起過程 / 高密度アレイ記録

Outline of Final Research Achievements

Seismic and tsunami records have been point-like in space, but recent technological advances start providing us with line-like or two-dimensional data, or no longer time-series but pictures or even videos. In this project, we have developed new approaches for such new data of high quality and vast quantity.
Using optical cable DAS data, a shallow marine structure of S-wave velocity was obtained of high resolution. Together with previous P-wave results, we can discuss its physical properties and constitutive materials for the first time. With ocean-bottom pressure data, we estimated detail fault motions of a marine earthquake that exited tsunamis, using a projection method of records, which is superior to conventional waveform inversions. In addition, a new atmosphere-ocean coupled event was identified and simulated for the 2022 Tonga volcanic eruption. We also monitored temporal variations of shallow seismic activities near a trench axis with continuous OBS records over 10 years.

Free Research Field

地震学

Academic Significance and Societal Importance of the Research Achievements

観測点数の少なさが制約の地震・津波研究は、1990年代からの観測網の整備に続き、光ファイバーを用いたDASや海底水圧計など最新の計測技術により、空間的に連続なデータや時間変化の検出が可能となってきた。従来と異なる複雑な処理過程を排した解析法の開発により、海底浅部の不均質構造や津波励起の海底地震の震源過程について、より高分解能・高信頼度の結果を本研究は可能とした。
稠密観測網は陸海両地域で今後一層展開され、さらに大量データが供給されるはずで、本研究での新しい視点が地震・津波研究で普及すれば、その解明に飛躍的発展するだけでなく、新たな有効な観測計画の構築立案にも貢献が期待される。