  Active faults release elastic strain energy via a whole continuum of modes of
slip, ranging from devastating earthquakes to Slow Slip Events and persistent
creep. Understanding the mechanisms controlling the occurrence of rapid,
dynamic slip radiating seismic waves (i.e. earthquakes) or slow, silent slip
(i.e. SSEs) is a fundamental point in the estimation of seismic hazard along
subduction zones. On top of showing slower rupture propagation velocity than
earthquakes, SSEs exhibit different scaling relationships, which could reflect
either different physical mechanisms or an intriguing lack of observations.
Like earthquakes, SSEs are bound to occur along unstable portions of active
faults, raising the question of the physical control of the mode of slip
(seismic or aseismic) along these sections. Here, we use the numerical
implementation of a simple rate-weakening fault model to explain the
spontaneous occurrence, the characteristics and the scaling relationship of
SSEs and earthquakes. We show that the simplest of fault geometrical
complexities with uniform friction properties can reproduce slow and fast
earthquakes without appealing to complex rheologies or mechanisms. Our model
helps resolve many of the existing paradoxes between observations and physical
models of earthquakes and SSEs.
