RUPTURE PROPAGATION, DYNAMIC FRONT SELECTION, AND THE ROLE OF SMALL LENGTH SCALES IN A MODEL OF AN EARTHQUAKE FAULT

We examine a model of rupture propagation on a one-dimensional earthqu ake fault, focusing both on the role of small length scales in control ling the dynamics and on the mechanisms by which propagating modes are selected. In order to obtain a well-defined continuum theory, we add a small amount of viscous dissipation to a previously studied model in which rupture propagation was controlled by a finite-difference grid spacing. We find that the dynamically selected rupture mode is one in which nearly free slip occurs in a pulse whose speed and shape are det ermined by a novel selection mechanism.