| 講演要旨(和文) | | 2007年能登半島地震で震度6強を観測した穴水町では,地震被害がK-NET観測点近傍に集中していたことが特徴的であった.地震後の現地探査によって,複雑な基盤構造が局所的な家屋被害集中の原因になったことが明らかにされたが,観測点近傍のより詳細な表層地盤物性構造を把握することを目的としてランドストリーマー高分解能S波反射法探査とS波検層を実施した.現地探査の結果,S波反射法によって基盤に対比される強い反射面をイメージングすることができた.この反射面は公園北西側半分では深度15m付近に出現するが,南東側に急激に深度を減じる.S波VSPでは深さ16m付近に出現する基盤上面の往復走時は反射探査での往復走時と一致した.また表層部の深さ2m-12m間にはVs |
|
|
| | 講演要旨(英文) | | We conducted high-resolution shallow seismic reflection surveying by means of Land Streamer and S-wave VSP near the K-NET Anamizu observatory station, Ishikawa Prefecture, central Japan. The survey site has been characterized as damage concentrated zone caused by the 2007 Noto Hanto earthquake. Aftershock observations and following field geophysical surveys had revealed an irregular shape of bedrock surface beneath the overlying very soft sediments. However the detailed geotechnical properties of the near-surface around the station were still uncertain. We then aimed to image the detailed structure of the near-surface at the site along with to obtain geophysical properties. As a result, CMP stacked sections clearly imaged the bedrock surface and detailed structure in the overlying sediments down to 20 m in depth. The bedrock surface rose southeast from 16 m to 4 m within 20 m along the lines. Measured S-wave velocities ranged from 60 m/s to 80 m/s for the overlying soft sediments. |
|
|
|
| |
|