Bursty crack propagation: Clusters, burst shapes and waiting times

We discuss the properties of bursty crack propagation in disordered solids, by considering a combination of data from planar crack front propagation experiments and numerical simulations of a crack line model. We focus on the spatial and temporal structure of the bursts or avalanches, by showing that each “global avalanche” consists of a number of “local clusters”, and that the activity bursts have a non-trivial average shape. Also the statistics of the waiting times separating two consecutive activity bursts is studied, and we demonstrate how their distribution develops a power-law form when increasing the threshold level used to define the avalanche events.