Fig. 1From: Viscous strengthening followed by slip weakening during frictional melting of chertRepresentative high-velocity frictional behavior of chert. a Experimental results showing the friction coefficient (black), axial displacement (blue), and normal stress (green) versus slip displacement. b–e Images captured using the digital video camera. Locations are shown in (a). b Wear materials are extruded after the initial slip weakening. c Reddish melt patches developed during slip strengthening. d Melt layer growth before second slip weakening. e Melt squeezing following the second slip weakeningBack to article page