[SCG61-03] Frictional properties of incoming sediments and rocks at shallow conditions of the Japan Trench subduction zone
Keywords:frictional properties, incoming sediments and rocks, shallow Japan Trench subduction zone
The results show that the steady-state friction coefficient μss decreases with increasing content of clay minerals at a given temperature. Although μss of a given sample does not change noticeably with increasing temperature up to 100°C, it increases with increasing temperature from 100°C to 200°C. a–b value (rate dependence of μss) decreases with increasing temperature, and becomes negative at 200°C where all samples showed stick-slip. However, the transition temperature at which a–b value becomes negative is different among four samples; ≈50°C for the chert sample, ≈100°C for the basalt sample, ≈125°C for the hemipelagic clay sample and ≈150°C for the pelagic clay sample. This implies that the transition temperature from aseismic faulting to seismic faulting is different among incoming sediments and rocks, suggesting that a heterogeneous distribution of asperities at the Japan Trench subduction zone as inferred from seismic studies possibly reflects the heterogeneous distribution of fault-zone materials along the plate boundary megathrust.