Theoretical studies predict that during earthquake rupture faults slide
at non-constant slip velocity, however it is not clear which source time
functions are compatible with the high velocity rheology of earthquake
faults. Here we present results from high velocity friction experiments
with non-constant velocity history, employing a well-known seismic
source solution compatible with earthquake source kinematics. The
evolution of friction in experiments shows a strong dependence on the
applied slip history, and parameters relevant to the energetics of
faulting scale with the impulsiveness of the applied slip function. When
comparing constitutive models of strength against our experimental
results we demonstrate that the evolution of fault strength is directly
controlled by the temperature evolution on and off the fault. Flash
heating predicts weakening behaviour at short timescales, but at larger
timescales strength is better predicted by a viscous creep rheology. We
use a steady-state slip pulse to test the compatibility of our strength
measurements at imposed slip rate history with the stress predicted from
elastodynamic equilibrium. Whilst some compatibility is observed, the
strength evolution indicates that slip acceleration and deceleration
might be more rapid than that imposed in our experiments.