Study on the elucidation and verification of the short-period ground motion generation process of sources for prediction of ground motions from mega-thrust earthquakes

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K14388
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 25030:Disaster prevention engineering-related
• Research Institution: Kyoto University
• Principal Investigator: Ito Eri 京都大学, 防災研究所, 特定助教 (70826726)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 短周期地震動生成域 / 不均質震源モデル / サイト増幅特性 / 建物被害評価モデル / 観測建物倒壊率 / 1944年東南海地震 / 1923年関東地震

Outline of Final Research Achievements

This study estimates the characteristics of strong ground motion generation areas (SMGAs) of earthquakes that generate seismic waves directly related to building damage, in order to mitigate damage from future megathrust earthquakes. For older earthquakes without observed seismic waves, we proposed to estimate the SMGAs by comparing the observed building collapse ratio obtained from documents and the building collapse ratio calculated in this study, instead of the observed and calculated seismic waves. For the 1923 Kanto earthquake, we estimated in detail the site amplification factors of the ground in the severely damaged area, which affects the building damage, and correlated them with the observed building collapse ratio, and then constructed a source model.

Free Research Field

地震工学

Academic Significance and Societal Importance of the Research Achievements

本研究により、1944年東南海地震の短周期地震動生成域が陸域の深い部分に存在することが分かった。これは東北地方太平洋沖地震と同じ傾向であり、この知見は今後海溝型巨大地震の短周期地震動生成域の特性を推定する際の一情報となり得る。また、この東南海地震が仮に再来した場合に、どんな地震波が現在の構造物を揺らすことになるのかが把握された。その結果を用いれば、現在の耐震性能を有する構造物の被害推定について、これまで中央防災会議などで予測震度を用いて推計されてきた経験的評価よりも、高精度な予測結果を今後提供することが可能になる。