| 講演要旨(和文) | | 著者らは,関東平野および相模湾周辺地域の深部地盤のS波速度構造モデルの妥当性を検証するために,同地域の16地点において微動の長期間連続観測を行い,地震波干渉法に基づくデータ処理によって表面波成分の抽出を試みてきた(地元ほか,2009).本研究では,さらに蓄積された200日以上の間の微動データを用いて得られる表面波の群速度と地下構造の関係について議論を行った.得られた相互相関関数のマルチプルフィルター解析によって,表面波の群速度の推定を得た.既存の深部地盤のS波速度構造モデル(山中・山田,2006)に対する理論値との比較によってモデルの検証を行った.関東平野内部の多くの地点では,群速度の理論値と観測値がよく一致していた.しかし,既存のモデルで地震基盤が露頭していると仮定されている伊豆関東や関東山地では,S波速度1.5km/s程度の堆積層を追加する必要があることがわかった. |
|
|
| | 講演要旨(英文) | | Surface wave group velocities were extracted with processing continuous data of three-component microtremors in the Kanto basin and Izu peninsula using the procedures based on the seismic inferferometry in order to validate the existing 3D S-wave velocity model of deep sediments by Yamanaka and Yamada in 2006. Cross correlations were calculated from the microtremors for every station pairs among 16 sites in the area. Dispersive waves in the cross correlations were identified as surface waves between the two sites. The group velocities for Love and Rayleigh waves were estimated from the multiple filtering analysis of the cross correlation. The observed group velocity of Rayleigh waves were compared with the theoretical ones calculated form the 3D S-wave velocity model of the deep sedimentary layers. The observed group velocities are similar to the theoretical ones at most of the sites in the basin area. However, significant differences were identified for the station pairs across the Sagami bay area and the Kanto mountains. It is concluded that the S-wave velocity in such an area must be improved. |
|
|
|
| |
|