| 講演要旨(和文) | | 2011年東北地方太平洋沖地震では宮城県栗原市で震度7，北海道から九州に渡る広い範囲で震度1から6の強い揺れを観測した．太平洋側の東北・関東地方では津波により大きな被害を受けた．また，品川や足柄平野（特に足柄平野）では，やや長周期地震動（周期2-3秒）が大きく，免震住宅が被害を受けている．本研究では，バックプロジェクション手法によりこのやや長周期地震動を生成した震源の破壊位置の推定を試みる．その結果，既存のスーパーアスペリティー位置と一致すること，また茨城県沖海溝寄りの寄与がある可能性がわかった． |
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| | 講演要旨(英文) | | The 2011 off the Pacific coast of Tohoku Earthquake (Mw 9.0) occurred at March 11, 2011. The largest seismic intensity, 7 was recorded in Kurihara, Miyagi and seismic intensity of 1 to 6- was recorded from Hokkaido to Kyushu. The Pacific coast around Tohoku and Kanto areas were deadly damaged by the Tsunami attack. Around Shinagawa area and Ashigara valley, medium-long period (2-3sec.) seismic motion was specifically large and base isolation structures were damaged in Ashigara area. In this study we estimated rupture areas which contributed to the medium-long period seismic motion using a back projection method. As a result, it was found that the estimated rupture areas agreed well with the super asperities off Ibaraki prefecture reported by the preceding studies. In addition to the super asperities, the large rupture area near the Japan Trench seemed to contribute to the medium-long period seismic motion. |
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