Offshore of the Wakasa-Bay area, reverse faults and folds that have grown mainly in Quaternary tend to align along the south-east flank of Oki Trough and the Echizen Bank Chain. The activities of these faults have not been resolved, but clear-cut fault topography, slope failure densely distributed along the south-east flank of the trough, bacterial mat and chimneys along the fault, and significant change of the thickness of Quaternary strata over the flexure, suggest the high activity of these NE-SW trending faults. On the other hand, in the Wakasa Bay area, eastward tilting erosion surfaces are displaced and delimited by N-S and NNW-SSW trending faults. These faults are situated at the northern end of the Tsurugawan-Isewan tectonic line and the Biwako-Seigan fault zone. So, the Wakasa Bay area is apparently located in different Quaternary tectonic zone from that offshore of the Wakasa-Bay area.
若狭湾周辺海域の第四紀構造運動
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