Multi-wavelength flux variability is a well-known signature of emission from active galactic nu-
clei and in particular from blazars. Rapid flares, with variability of the order of a few days and
below, are frequently observed at high energies from these objects. While many physical inter-
pretations have been proposed for individual flare events, based on radiative models with varying
degrees of complexity, a general picture of their physical origin is still lacking.
Here we focus on a description of rapid flares as isolated events, for which a description based on
a single compact emission region is appropriate. We have explored the parameter space of a one-
zone synchrotron self-Compton model for different scenarios leading to flares due to temporary
perturbations of a steady state. Such perturbations can be based on additional particle injection,
diffusive shock acceleration, or stochastic acceleration on turbulence. The time-dependent EM-
BLEM code has been used to solve the kinetic equation describing the evolution of the electron
distribution, simulate broad-band spectral distributions and multi-wavelength light curves.
We have identified observable signatures in the shape of the resulting light curves and in the rela-
tive amplitudes between different bands to distinguish between these generic scenarios.