Fig. 9: Conceptual sketch exhibiting the observed positive correlation between the amount of amorphous material found in fault gouges with peak slip rate.
To qualitatively assess the degree of amorphization, the spot size for selected area electron diffraction (SAED) was kept constant. As comminution and melting are material specific processes, we selected areas that are exclusively made of feldspar. The calculated work (W) and power (dW/dt) together with the measured or estimated failure durations (t) demonstrate that power changes by 8 orders of magnitude whereas work only by a factor of 3 to 5. The range of W in the dry dynamic case results from either using the full shear stress - slip curve to compute Wtot (upper bound estimate) or only the fraction of the work that corresponds to pre-peak slip and an idealised slip weakening behaviour from peak stress to a residual strength of 40 MPa with a slip weakening distance of 1.5 mm as in the quasistatic dry test.
