  Similarities between force-driven compression experiments of porous materials
and earthquakes have been recently proposed. In this manuscript, we measure the
acoustic emission during displacement-driven compression of a porous glass. The
energy of acoustic-emission events shows that the failure process exhibits
avalanche scale-invariance and therefore follows the Gutenberg-Richter law. The
resulting exponents do not exhibit significant differences with respect the
force-driven case. Furthermore, the force exhibits an avalanche-type behaviour
for which the force drops are power-law distributed and correlated with the
acoustic emission events.
