| 講演要旨(和文) | | 千葉県旭市の海浜沿いで反射法地震探査による浅部地下構造調査を実施した．主な仕様は震源：P波油圧インパクタ，測点間隔：2m，最大オフセット：382m，測線長7km等である．得られた発震記録では，見掛け速度約1.6km/sの初動が最大オフセットまで達し，反射波は往復走時900ms程度まで見られる．簡易データ処理で作成した予備的なCMP重合断面で，数10msの極浅部に沖積層のほぼ水平で凹凸のある反射面，それ以深の900msまでに見掛け南西傾斜の上総層群と先新第三系の上限が捉えられた． |
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| | 講演要旨(英文) | | We conducted a shallow seismic reflection survey along NE-SW coastal line at the Kujukuri coastal plain (Asahi city, Yasashigaura), Chiba Prefecture, central Japan. The seismic source is a P-wave Yuatsu impactor, station interval is 2m, the maximum source-receiver offset is 382m and the survey line is 7km long. In vertical stacked and gained shot records, first breaks reach the maximum offset with 1.6km/s apparent velocity and reflection waves are recognized down to 900ms in two way time. In preliminary CMP stacked time section by simple data processing, uneven reflectors of alluvial sediments are imaged in the shallowest part at several ten ms, and dipping reflectors of Kazusa group and pre-Tertiary basement top are perceived bellow them. Reflectors deeper than 700m are recognized by simple survey system of single receivers. |
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