  It has been long stated that there are profound analogies between fracture
experiments and earthquakes; however, few works attempt a complete
characterization of the parallelisms between these so separate phenomena. We
study the Acoustic Emission events produced during the compression of Vycor
(SiO2). The Gutenberg-Richter law, the modified Omori's law, and the law of
aftershock productivity are found to hold for a minimum of 5 decades, are
independent of the compression rate, and keep stationary for all the duration
of the experiments. The waiting-time distribution fulfills a unified scaling
law with a power-law exponent close to 2.45 for long times, which is explained
in terms of the temporal variations of the activity rate.
