| 講演要旨(和文) | | 地震時に少しでも早く警報を出力するために，地表P波から地表S波を予測する手法はオンサイトの早期地震警報として有効である．本研究では，関東平野内および周辺のKiK-net観測点で観測された最大振幅によって地表P波と地表S波の関係を評価し，地下速度構造が及ぼす影響について考察した．その結果，地表におけるP波とS波の関係における地下速度構造による地震動増幅の影響は，震源特性や伝播経路特性の影響と比較して大きく，P波とS波の増幅率の差は観測点によって顕著な違いが現れることを確かめた．また，最大振幅の相関係数を確認し，地中，地表ともにP波からS波を予測する場合には，地下速度構造による地震動増幅のバラツキの影響よりも，各地震のラディエーションや伝播経路による減衰のバラツキの影響が大きいことを確かめた． |
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| | 講演要旨(英文) | | It is effective to directly predict earthquake ground motions using P-waves on the surface for earthquake early warnings. In this study, we evaluated the influence of site amplifications by velocity structures on relationships between P-waves and S-waves on the surface using seismic records of KiK-net stations in and around Kanto Basin. By evaluating relationships of peak amplitudes, we demonstrated that site amplifications by velocity structures more strongly affect relationships between P-waves and S-waves on the surface than source and path effects. In addition, we confirmed that correlation coefficients between peak amplitudes of P-waves and S-waves observed on the surface have almost the same range as those in deep boreholes because both relationships between P-waves and S-waves on the surface and those in deep boreholes are affected by the variability of radiation patterns and propagation paths by individual earthquakes. |
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