| 講演要旨(和文) | | 山岳地で実施したP波屈折法の記録に、表面波探査および微動アレイ探査の解析を適用し、S波速度構造を推定した。測定は単点型の測定器46台と固有周波数2Hzの速度型地震計を50m間隔で設置して行った。サンプリングは1msとし3時間の連続記録を取得した。地表もしくは発破孔の深度0.6〜14mにおいて100〜3000gのダイナマイトによる起振を14か所で行った。全ての発破記録において、表面波と思われる明瞭な後続波が認められ、周波数2〜10Hzの範囲で約2500m/sの位相速度を持つ分散曲線が得られた。常時微動に対して空間自己相関関数の解析を行ったところ、周波数0.4〜4Hzの範囲で、2500〜4000m/sの位相速度を持つ分散曲線が得られた。発破記録と常時微動から得られた分散曲線は周波数2〜4Hzの範囲でほぼ一致した。得られた分散曲線に逆解析を適用し、深度1km程度までのS波速度を推定できた。 |
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| | 講演要旨(英文) | | We analyzed seismic refraction data obtained at mountainous area in terms of the analyses of surface wave methods and microtremor array measurements and estimated an S-wave velocity profile. Forty-six stand-alone seismographs and 2 Hz vertical component of geophones with spacing of 50 m were used in data acquisition. Seismic data were continuously recorded with a sampling time of 1 ms. We exploded 100 ~ 3000 g of water gel explosive at 14 locations with depths of 0.6 ~ 20 m. Clear later waves corresponding to surface waves appeared in all shot records and dispersion curves with a phase velocity of approximately 2500 m/s were recognized in a frequency range between 2 ~ 10 Hz. Spatial auto-correlation analysis was applied to ambient noise and a dispersion curve with a phase velocity from 2500 ~ 4000 m/s was recognized in a frequency range between 0.4 ~ 4 Hz. Dispersion curves obtained from the shot records and the ambient noise agreed with each other in a frequency range between 2 ~ 4 Hz. Non-linear inversion was applied to the dispersion curves and an S-wave velocity profile to a depth more than 1 km was estimated. |
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