| 講演要旨(和文) | | KiK-net一関西観測点(IWTH25)では,2008年6月14日岩手・宮城内陸地震で4000galを超える地震動が観測された.この大振幅の地震波発生のメカニズム解明に資するため,観測点周辺において屈折法探査,電気探査,表面波探査を実施し,表層地盤特性の解明を試みた.調査地において,表土が厚さ1〜3m,P波速度Vp=400〜500m/s,S波速度Vs=150〜200m/s,その下の段丘堆積層はP波速度Vp=800〜1000m/s,S波速度Vs=250〜450m/sであり,地下水位は段丘堆積層内の深さ5〜6mの位置に推定された. |
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| | 講演要旨(英文) | | The 2008 Iwate-Miyagi Nairiku earthquake produced relatively high-frequency ground motions, which resulted in the 4g acceleration at the KiK-net IWTH25 station. We conducted a seismic refraction survey, surface wave survey, and resistivity survey at the site around the station IWTH25 to understand the mechanism of the strong high-frequency ground motion. The result shows the velocity at the shallow subsurface layer is slower than PS logging data, Vp=400-500m/s, Vs=150-200m/s, and the depth of the layer can be estimated as 1-3m. |
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