Abstract
The question “what arrests an earthquake rupture?” sits at the heart
of any potential prediction of earthquake magnitude. Here, we use a
one-dimensional, thin-elastic-strip, minimal model, to illuminate the
basic physical parameters that control the arrest of large ruptures. The
generic formulation of the model allows for wrapping various earthquake
arrest scenarios into the variations of two dimensionless variables
$\bar \tau_k$ (initial pre-stress on
the fault) and $\bar d_c$ (fracture energy), valid for
both in-plane and antiplane shear loading. Our continuum model is
equivalent to the standard Burridge-Knopoff model, with an added
characteristic length scale, $H$, that corresponds to either the
thickness of the damage zone for strike-slip faults or to the thickness
of the downward moving plate for subduction settings. We simulate the
propagation and arrest of frictional ruptures and derive closed-form
expressions to predict rupture arrest under different conditions. Our
generic model illuminates the different energy budget that mediates
crack- and pulse-like rupture propagation and arrest. It provides
additional predictions such as generic stable pulse-like rupture
solutions, stress drop independence of the rupture size, the existence
of back-propagating fronts, and predicts that asymmetric slip profiles
arise under certain pre-stress conditions. These diverse features occur
also in natural earthquakes, and the fact that they can all be predicted
by a single minimal framework is encouraging and pave the way for future
developments of this model.