Failure of porous materials under compression: statistical aspects of labquakes

There are profound analogies between fracture experiments and earthquakes; however, few works attempt a complete characterization of the parallels between these so separate phenomena. We have studied the acoustic emission (AE) events produced during the compression of porous SiO2 (Vycor). The distribution of avalanche energies (Gutenberg-Richter law), the rate of aftershocks (modified Omori’s law), and the law of aftershock productivity hold for a minimum of 5 decades. These laws are independent of the compression rate, and keep stationary for all the duration of the experiments. The waiting-time distributions fulfils a unified scaling law with a decaying power-law exponent close to 1.0 for short times and close to 2.5 for long times. Results for other porous materials will also be discussed.