The dynamics of frictional sliding in stick-slip for a precut Westerly granite is studied at elevated pressures. Piston displacement measured outside the pressure vessel shows a small but significant delay (~2 ms) during a stick-slip. As a result, most part of the stress-drop occurs with little piston displacement while most piston displacement occurs while the stress has already dropped to a residual level, giving a peculiar ''L''-shape in the stress-displacement curve. On the other hand, displacement measured using an internal transducer mounted directly across the rock fracture shows that most slip on the rock fracture occurs concurrently with stress-drop. Based on the directly measured stress-displacement histories, we estimate a critical slip-weakening displacement of 200 &mgr;m and a shear-fracture energy of 300 J/m2 at a normal stress of 85 MPa. This result shows that the discrepancy between the extrapolated values for the shear fracture energy [Okubo and Dieterich, 1984> and the estimated values given here and by Rice [1980> cannot be accounted for by different modes of measuring displacement.