Real-time correction of tsunami site effect by frequency-dependent tsunami-amplification factor for tsunami forecast

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K16309
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Natural disaster / Disaster prevention science
• Research Institution: Japan, Meteorological Research Institute
• Principal Investigator: Tsushima Hiroaki 気象庁気象研究所, 地震津波研究部, 併任(第四研究室) (00589864)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: リアルタイム津波予測 / 津波増幅率 / 近地津波 / 周波数特性 / 自然災害

Outline of Final Research Achievements

For tsunami early warning, I developed frequency-dependent tsunami-amplification factor. When offshore and coastal observing points are close, the spectral ratio between the two points can be regarded as site response (i.e. frequency-dependent amplification factor). In this study, tsunami waveforms calculated by tsunami numerical simulations were used to obtain spectral ratio. An average of the resulted spectral ratios from more than 100 tsunamigenic-earthquake scenarios is regarded as frequency-dependent amplification factor. The estimated factor differs depending on an observing location even in a same bay. The estimated amplification factor is used to design a recursive digital filter that can be applicable in time domain. The designed filter shows good performance in real-time correction of tsunami-height amplification due to site effect.

Free Research Field

地震学、津波

Academic Significance and Societal Importance of the Research Achievements

リアルタイム津波予測は、津波被害を軽減する上で有効な手段の一つである．沿岸の津波の高さを精度良く予測するには、津波の波源を精度良く推定し、それをもとに津波の伝播過程を迅速かつ精度良く算出する必要がある。後者については、高分解能の地形データを用いた津波伝播のコンピュータシミュレーションの活用が有効だが、リアルタイムに行うには計算コストが高い。他方、本研究で提案した方法を用いれば、沿岸付近の津波伝播特性を、短時間かつ簡便にリアルタイム津波予測に組み込める。これにより、高性能コンピュータのリアルタイム活用が困難な状況でも、一定程度の精度を確保した津波予測が実現できるようになるものと期待される。