| 講演要旨(和文) | | 四国西部佐田岬半島の伊方において深度2000m,500m160m,5mの各孔の孔底に地震計を設置する工事を2012年12月に完了し, 地震観測を行っている. 大深度の鉛直アレイで観測された2014年3月14日の伊予灘地震の記録に対して, 伝達関数の逆解析を用いた減衰定数の推定を行っていたが，得られた減衰定数に対して伝達関数の更なるフィッティングの向上と解の選択方法について検討した. 減衰定数の表層の層構造を細かくすることでフィッティングが向上した. 複数回の逆解析後のパラメータを選択する際には伝達関数のデータセットを保ったまま最適な解を選択することを試みた. |
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| | 講演要旨(英文) | | In Ikata, Ehime Prefecture in the west part of Shikoku Island, a seismic recording system in a deep borehole was deployed in December of 2012. Seismographs were installed at 2000m, 500m, 160m and 5m depth respectively, and have been recording ever since. We have estimated attenuation parameters in the deep borehole by using Q value inversion of data recorded during the Iyo-nada earthquake which occurred on March 14, 2014. The aim of this study is to further improve the fit of the transfer function result found previously [1], and examines ways to select the optimal solution from a large number of trials. As a result, we found that finely subdividing the attenuation structure depths close to the surface, (i.e. less than 300m) enabled a better transfer function fitting. Also, we tried to select an optimal solution from a large amount of inversions that is consistent with the transfer function data set corresponding to each trial. |
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