Two types of avalanche behaviour in model granular media

We have described a lattice model of a sandpile that includes a coupling between evolving granular structures and dynamic responses. The coupling manifests as a granular memory. We have illustrated the role of memory by observing avalanches in a (three)-dimensional model sandpile. There are two distinct classes of dynamic events that depend on the process history and mimic, closely, two categories of avalanches recently observed in piles of glass beads. The origins of the different dynamic regimes are explained in terms of the statistical distribution of local stability criteria.