[H-DS07] Seismic hazards on subduction earthquakes and active faults in the Central Japan

[HDS07-P02] Paleoseismological trenching surveys on the Enasan-Sanageyamakita fault zone, Central Japan

*Takashi Azuma¹, Norio Shigematsu¹, Rei Nakashima¹, Ken-ichi Yasue², Ryo Tateishi², Daisuke Hirouchi³ (1.National Institute of Advanced Industrial Science and Technology, 2.Toyama University, 3.Shinshu University)

Keywords:active fault, Central Japan, Paleoseismological trenching survey

We conducted paleoseismological trench surveys at 2 sites on the Enasan-Sanageyamakita fault zone.
This fault zone is consisted with the Enasan fault (38 km in length) and the Sanageyamakita fault (22 km). One site is Tomida on the Enasan fault, where is close to a previous trenching survey site by Gifu Prefecture in 2001. In our trench, 2 fault planes with high angle were recognized, whereas this fault is evaluated as a reverse fault.Another site is Higashi-shirasaka on the Sanageyama-kita fault, where is same site with a previous trenching survey by Aichi Prefecture in 1996. In the trench, low-angle fault planes were recognized, whereas this fault is evaluated as a high-angle right-lateral strike-slip fault. It cut sand-silt sediments and covered with gravels. We will discuss faulting histories these sites on this fault zone. This survey was a part of the Comprehensive Research Project for the Enasan-Sanageyama-Kita Fault Zone by MEXT.