| 講演要旨(和文) | | 九十九里低地の3箇所で，反射法地震探査による地下構造調査を実施した．沖積層基底付近の反射面は横芝光町域と旭市域では凹凸を伴い局所的な凹部は埋没谷と考えられる．旭市域の反射面は先中新統基盤上面まで捉えられ，測線内での基盤深度は900mに達する．さらに，反射面の連続性は非常に良好で，堆積層は整合で成層構造を成し，基盤上面も鮮明である．堆積層中に高角の断層が見られる． |
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| | 講演要旨(英文) | | Seismic reflection surveys were conducted in the coastal area of the Kujukuri plain, Chiba Prefecture. Reflectors near the bottom of the alluvial sediment are flat in a seismic section of Kujukuri town, but they are neither flat nor smooth and have concaves in seismic sections of Yokoshibahikari town and Asahi city. Bellow the alluvial sediment, reflectors are discontinuous and do not have specific dips in seismic sections of Kujukuri town and Yokoshibahikari town. On the contrary, reflectors are very continuous, show conformity and parallel bedding in Asahi city. The deeper are the sediment layers, the larger are their dips and thickness. The top of pre-Neogene basement is very clear and dips southwestward. High angle faults are interpreted in seismic sections of the three lines, especially they are remarkable in Asahi city. |
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