1:45 PM - 2:00 PM
[SCG61-01] Fault zone development in the West Tottori area, Japan
Keywords:Tottori Prefecture, active fault, fault rocks, earthquake
XRD analysis showed that the gouge in the central part of the aftershock area is mainly composed of illite and chlorite (Kobayashi et al., 2006; Manaka et al., 2012), while the gouges in the NW and SE parts of the aftershock area (Kaneki et al., 2019) and those along the Nichinanko lineament (Manaka et al., 2012) are rich in halloysite. Chemical processes are different between these fault rock zones. In the central part of the aftershock area, most gouges were formed at a higher temperature than the neighborhood. On the other hand, the latest gouge is rich in smectite at Ryokusuien.
These facts suggest that the maturity of the fault zone along the aftershock area has been a low level, WNW strike fault planes (R1 shears) and ENE strike fault planes (R2 shears) formed predominantly. Therefore, the early kinematic (dextral) and chemical (illite-chlorite forming hydrothermal alteration) processes are remained. On the other hand, the activity along the Nichinanko lineament has been a higher level in a shallower depth (halloysite-smectite forming environment), NW strike fault planes (Y surfaces) formed predominantly, the remarkable Nichinanko lineament developed. In addition, the Komachi-Ohdani lineament system (L=12km) which runs the NE of the aftershock area also developed. How these fault zones have developed over a long period of time will be discussed.