Fig. 4From: Inelastic behavior and mechanical strength of the shallow upper crust controlled by layer-parallel slip in the high-strain zone of the Niigata region, JapanFriction coefficients of fault gouges (KAT01, 03) generated by bedding-plane slip and of mudstones (KAT02, 04). Double-direct shear tests of four samples (KAT01, 02, 03, and 04) on two sliding planes were performed as in previous studies (Kawai et al. 2015). D: DepthBack to article page