[S-SS34_29PO1] Active faults and paleoseismology

[SSS34-P10] Pit excavation along the Tachikawa fault at Sayama Shrine Site

*Tatsuya ISHIYAMA¹, Daisuke HIROUCHI², Hiroshi SATO¹, Takehiko SUZUKI³, Kenta KOBAYASHI⁴, Yorihide KORIYA⁵, Masashi OMATA⁵, Tsuyoshi SHIBATA⁶ (1.Earthquake Research Institute, University of Tokyo, 2.Department of Education, Shinshu University, 3.Faculty of Urban Environmental Sciences, Tokyo Metropolitan University, 4.Department of Geology, Faculty of Science, Niigata University, 5.Crearia, Inc., 6.Aero Photo Center)

We excavated a 10-m-long, 2-m-deep pit across the hypothesized south-facing topographic scarp on along the Tachikawa fault. Preliminary results include clear evidence of accumulated, west-facing monoclonal folding of underlying conglomerates, predicted by the topographic scarp. Asymmetric ductile shear zone exposed on the bottom indicate nature of significant sinistral strike-slip component of faulting, rather than a simple reverse faulting. Future works include establishing stratigraphy based on radiocarbon dating and tephrostratigraphy.