| 講演要旨(和文) | | 2011年東北地方太平洋沖地震以降，首都圏での地震活動が増加しており，今後，立川断層等による活断層による被害地震の発生が危惧されるため，首都圏では精度の高い強震動予測が必要とされる．本研究では，立川断層における強震動予測のための3次元地下構造モデルの作成を目的として，立川断層帯周辺地域で観測された地震記録からレシーバー関数法を用いた解析を実施し，当該地域の深部地下構造を推定することにより，立川断層帯による基盤の段差構造を含めたより詳細な3次元地下構造を推定した．レシーバー関数法を用いたインバージョン解析の結果，立川断層における基盤は北東落ちであり，その段差は約1.8kmとなった．これに対して，名栗断層では南西落ちとなり，その段差は約0.3kmであるとともに，更なる地盤構造に対する精査が求められる． |
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| | 講演要旨(英文) | | Tachikawa fault is one of the most activity faults in the Tokyo metropolitan area and when large earthquake will occur by this fault in the near future, it is expected that large economic and human loss will happen around this area. However, three dimensional subsurface structural model is not clear still enough for the estimation of the strong ground motions in this area. In this study, we estimated the three dimensional subsurface structural model using the receiver function method from the obtained records of the K-NET, KiK-NET and SK-net. The 60 earthquake ground motion stations were used in this area. We calculated the receiver functions from 20 to 50 seismic records obtained at each station, and we identified the subsurface structural model using inversion based on the simulated annealing method. Based on numerical experiments it is indicated that thickness of individual layers are inverted very well. Moreover, we constructed the three dimensional subsurface structural model in this area obtained from P-wave and S-wave velocity profiles of thick sediments at each station. The results indicate that a basement depth in those profiles at down-thrown side of the fault is larger than that at up-thrown side with a difference of about 1.8km. |
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