BASS, an alternative to ETAS

The epidemic type aftershock sequence ( ETAS) model has been widely used to model the statistics of seismicity. An essential feature of the ETAS model is the concept of generations of aftershocks. A mainshock has primary aftershocks, the primary aftershocks have secondary aftershocks, and so forth. In this paper, we introduce the branching aftershock sequence ( BASS) model as an alternative to ETAS. The BASS model is fully self-similar whereas the ETAS model is not. Furthermore, the ETAS model requires the specification of branching (parent-daughter) ratios, while the BASS model instead utilizes Bath's law. We also show that the branching statistics in the BASS model are identical to the self-similar Tokunaga statistics of drainage networks.