[S-CG52] 変動帯ダイナミクス

[SCG52-18] 三河湾周辺の基盤構造から推定された半地溝構造とその反転テクトニクスに伴う活断層

*宮川 歩夢¹、阿部 朋弥¹、住田 達哉¹、大坪 誠² (1.国立研究開発法人　産業技術総合研究所 地質情報研究部門、2.国立研究開発法人　産業技術総合研究所 活断層・火山研究部門)

キーワード：重力探査、反転テクトニクス、三河湾地域、知多半島、内海断層、高浜断層

The Mikawa Bay Region, central Japan, is characterized by many active faults recording Quaternary activities. It is, however, difficult to understand the overall tectonic character of the region due to a thick sedimentary cover. We report the finding of basin inversion by estimating the depth and structure of the basement surface by analyzing gravity data. Our gravity survey revealed a half-graben bounded on the souther edge of Chita Peninsula by the north-dipping Utsumi Fault. The motion of the Utsumi Fault, which inverted from normal faulting during the Miocene to recent reverse faulting, indicated the inversion of the half-graben. The Takahama Fault in the southwestern part of the Nishi–Mikawa Plain is considered to have formed as a result of the backthrust of the Utsumi Fault under inversion tectonics.