[S-SS13] 活断層と古地震

[SSS13-P09] 森本・富樫断層帯中央部の深部構造探査

*石山 達也¹、佐藤 比呂志^1,5、平松 良浩²、岩田 知孝³、斉藤 秀雄⁴、石毛 宏和⁴、阿部 進⁴ (1.東京大学地震研究所、2.金沢大学理工研究域地球社会基盤学系、3.京都大学防災研究所、4.株式会社地球科学総合研究所、5.静岡大学防災総合センター)

キーワード：活断層、深部構造探査、森本・富樫断層帯

To define subsurface fault geometry, structural characters of fault-related folds and their structural growth during Quaternary, we collected ca. 24 km long, onshore multi-channel deep seismic reflection data across the central portion of the Morimoto-Togashi Fault Zone (MTFZ), an active reverse fault system located in the southwest extension of the Toyama trough, by using four Enviro-vib trucks as seismic sources and more than 970 seismic channels. Seismic reflection processing reveals the detailed subsurface structure in accordance with P-wave velocity structures obtained by refraction tomography. The depth-converted section that was correlated with the local Neogene strata successfully shows a moderately east-dipping reverse fault plane that is overlain by a monocline of Miocene to Pleistocene sedimentary units. We will also briefly explore structural relationships of folded middle-late Pleistocene fluvial terraces along the MTFZ and the fault trajectories and the growth of the fault-related folds.

Acknowledgements: This work was supported by MEXT “Comprehensive Research Project for the Morimoto-Togashi Fault Zone”.