  A model for fault dynamics consisting of two rough and rigid brownian
profiles that slide one over the other is introduced. An earthquake occurs when
there is an intersection between the two profiles. The energy release is
proportional to the overlap interval. Our model exhibits some specific features
which follow from the fractal geometry of the fault: (1) non-universality of
the exponent of the Gutenberg-Richter law for the magnitude distribution; (2)
presence of local stress accumulation before a large seismic event; (3)
non-trivial space-time clustering of the epicenters. These properties are in
good agreement with various observations and lead to specific predictions that
can be experimentally tested.
