| 講演要旨(和文) | | 盛岡市の市街地に位置する青山地区と本宮地区を対象に，比較的大きいサイズの３成分微動アレイ探査を行った．自動車の交通などノイズの大きい観測条件下でも空間自己相関法と周波数波数解析法の2種類の手法を用いてLove波の位相速度の検出に成功した．過去の研究より大きいアレイ半径100mの場合でもLove波の位相速度分散曲線を得ることができた．しかし，半径400mと1000mでは分散曲線のばらつきが大きい場合が散見された．これは青山地区と本宮地区の基盤深度が空間変化しているためであると考えられる．上下動の微動データから得られるRayleigh波のみを用いてS波速度構造を推定した場合，層厚とS波速度にトレードオフが生じS波速度構造がユニークに決まらなかったが，Rayleigh波とLove波の分散曲線を用いてS波速度構造を推定した場合，拘束条件が増え，S波速度構造をユニークに推定することができた． |
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| | 講演要旨(英文) | | Three-component microtremor exploration with a large size array was conducted in Aoyama and Motomiya districts located in an urban area of Morioka city. We have succeeded in estimating Love wave phase velocities by using two methods of spatial autocorrelation method and frequency wavenumber analysis method under noisy observation conditions such as traffic noises. The phase velocity dispersion curve of Love waves was obtained even with an array radius of 100m, which was larger than one used in previous studies. However, there were some cases where the dispersion curve varied at radii of 400m and 1000m. It is thought to be due to change spatially sin the basement depths of the Aoyama and Motomiya districts. When the S wave velocity structure was estimated using only the Rayleigh wave obtained from the microtremor data of the vertical motion, there was a trade-off between the layer thickness and the S wave velocity, and the S wave velocity structure was not uniquely determined. When the S wave velocity structure was estimated using the wave dispersion curve of Love and Rayleigh waves, the constraint conditions increased and the S wave velocity structure could be estimated uniquely. |
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